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• What Is a Case Study? | Definition, Examples & Methods

What Is a Case Study? | Definition, Examples & Methods

Published on May 8, 2019 by Shona McCombes . Revised on November 20, 2023.

A case study is a detailed study of a specific subject, such as a person, group, place, event, organization, or phenomenon. Case studies are commonly used in social, educational, clinical, and business research.

A case study research design usually involves qualitative methods , but quantitative methods are sometimes also used. Case studies are good for describing , comparing, evaluating and understanding different aspects of a research problem .

Table of contents

When to do a case study, step 1: select a case, step 2: build a theoretical framework, step 3: collect your data, step 4: describe and analyze the case, other interesting articles.

A case study is an appropriate research design when you want to gain concrete, contextual, in-depth knowledge about a specific real-world subject. It allows you to explore the key characteristics, meanings, and implications of the case.

Case studies are often a good choice in a thesis or dissertation . They keep your project focused and manageable when you don’t have the time or resources to do large-scale research.

You might use just one complex case study where you explore a single subject in depth, or conduct multiple case studies to compare and illuminate different aspects of your research problem.

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Once you have developed your problem statement and research questions , you should be ready to choose the specific case that you want to focus on. A good case study should have the potential to:

• Provide new or unexpected insights into the subject
• Challenge or complicate existing assumptions and theories
• Propose practical courses of action to resolve a problem
• Open up new directions for future research

TipIf your research is more practical in nature and aims to simultaneously investigate an issue as you solve it, consider conducting action research instead.

Unlike quantitative or experimental research , a strong case study does not require a random or representative sample. In fact, case studies often deliberately focus on unusual, neglected, or outlying cases which may shed new light on the research problem.

Example of an outlying case studyIn the 1960s the town of Roseto, Pennsylvania was discovered to have extremely low rates of heart disease compared to the US average. It became an important case study for understanding previously neglected causes of heart disease.

However, you can also choose a more common or representative case to exemplify a particular category, experience or phenomenon.

Example of a representative case studyIn the 1920s, two sociologists used Muncie, Indiana as a case study of a typical American city that supposedly exemplified the changing culture of the US at the time.

While case studies focus more on concrete details than general theories, they should usually have some connection with theory in the field. This way the case study is not just an isolated description, but is integrated into existing knowledge about the topic. It might aim to:

• Exemplify a theory by showing how it explains the case under investigation
• Expand on a theory by uncovering new concepts and ideas that need to be incorporated
• Challenge a theory by exploring an outlier case that doesn’t fit with established assumptions

To ensure that your analysis of the case has a solid academic grounding, you should conduct a literature review of sources related to the topic and develop a theoretical framework . This means identifying key concepts and theories to guide your analysis and interpretation.

There are many different research methods you can use to collect data on your subject. Case studies tend to focus on qualitative data using methods such as interviews , observations , and analysis of primary and secondary sources (e.g., newspaper articles, photographs, official records). Sometimes a case study will also collect quantitative data.

Example of a mixed methods case studyFor a case study of a wind farm development in a rural area, you could collect quantitative data on employment rates and business revenue, collect qualitative data on local people’s perceptions and experiences, and analyze local and national media coverage of the development.

The aim is to gain as thorough an understanding as possible of the case and its context.

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In writing up the case study, you need to bring together all the relevant aspects to give as complete a picture as possible of the subject.

How you report your findings depends on the type of research you are doing. Some case studies are structured like a standard scientific paper or thesis , with separate sections or chapters for the methods , results and discussion .

Others are written in a more narrative style, aiming to explore the case from various angles and analyze its meanings and implications (for example, by using textual analysis or discourse analysis ).

In all cases, though, make sure to give contextual details about the case, connect it back to the literature and theory, and discuss how it fits into wider patterns or debates.

If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.

• Normal distribution
• Degrees of freedom
• Null hypothesis
• Discourse analysis
• Control groups
• Mixed methods research
• Non-probability sampling
• Quantitative research
• Ecological validity

Research bias

• Rosenthal effect
• Implicit bias
• Cognitive bias
• Selection bias
• Negativity bias
• Status quo bias

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Blog Business How to Present a Case Study like a Pro (With Examples)

How to Present a Case Study like a Pro (With Examples)

Written by: Danesh Ramuthi Sep 07, 2023

Okay, let’s get real: case studies can be kinda snooze-worthy. But guess what? They don’t have to be!

In this article, I will cover every element that transforms a mere report into a compelling case study, from selecting the right metrics to using persuasive narrative techniques.

And if you’re feeling a little lost, don’t worry! There are cool tools like Venngage’s Case Study Creator to help you whip up something awesome, even if you’re short on time. Plus, the pre-designed case study templates are like instant polish because let’s be honest, everyone loves a shortcut.

Click to jump ahead: 

What is a case study presentation?

What is the purpose of presenting a case study, how to structure a case study presentation, how long should a case study presentation be, 5 case study presentation examples with templates, 6 tips for delivering an effective case study presentation, 5 common mistakes to avoid in a case study presentation, how to present a case study faqs.

A case study presentation involves a comprehensive examination of a specific subject, which could range from an individual, group, location, event, organization or phenomenon.

They’re like puzzles you get to solve with the audience, all while making you think outside the box.

Unlike a basic report or whitepaper, the purpose of a case study presentation is to stimulate critical thinking among the viewers. 

The primary objective of a case study is to provide an extensive and profound comprehension of the chosen topic. You don’t just throw numbers at your audience. You use examples and real-life cases to make you think and see things from different angles.

The primary purpose of presenting a case study is to offer a comprehensive, evidence-based argument that informs, persuades and engages your audience.

Here’s the juicy part: presenting that case study can be your secret weapon. Whether you’re pitching a groundbreaking idea to a room full of suits or trying to impress your professor with your A-game, a well-crafted case study can be the magic dust that sprinkles brilliance over your words.

Think of it like digging into a puzzle you can’t quite crack . A case study lets you explore every piece, turn it over and see how it fits together. This close-up look helps you understand the whole picture, not just a blurry snapshot.

It’s also your chance to showcase how you analyze things, step by step, until you reach a conclusion. It’s all about being open and honest about how you got there.

Besides, presenting a case study gives you an opportunity to connect data and real-world scenarios in a compelling narrative. It helps to make your argument more relatable and accessible, increasing its impact on your audience.

One of the contexts where case studies can be very helpful is during the job interview. In some job interviews, you as candidates may be asked to present a case study as part of the selection process.

Having a case study presentation prepared allows the candidate to demonstrate their ability to understand complex issues, formulate strategies and communicate their ideas effectively.

The way you present a case study can make all the difference in how it’s received. A well-structured presentation not only holds the attention of your audience but also ensures that your key points are communicated clearly and effectively.

In this section, let’s go through the key steps that’ll help you structure your case study presentation for maximum impact.

Let’s get into it. 

Open with an introductory overview 

Start by introducing the subject of your case study and its relevance. Explain why this case study is important and who would benefit from the insights gained. This is your opportunity to grab your audience’s attention.

Explain the problem in question

Dive into the problem or challenge that the case study focuses on. Provide enough background information for the audience to understand the issue. If possible, quantify the problem using data or metrics to show the magnitude or severity.

Detail the solutions to solve the problem

After outlining the problem, describe the steps taken to find a solution. This could include the methodology, any experiments or tests performed and the options that were considered. Make sure to elaborate on why the final solution was chosen over the others.

Key stakeholders Involved

Talk about the individuals, groups or organizations that were directly impacted by or involved in the problem and its solution. 

Stakeholders may experience a range of outcomes—some may benefit, while others could face setbacks.

For example, in a business transformation case study, employees could face job relocations or changes in work culture, while shareholders might be looking at potential gains or losses.

Discuss the key results & outcomes

Discuss the results of implementing the solution. Use data and metrics to back up your statements. Did the solution meet its objectives? What impact did it have on the stakeholders? Be honest about any setbacks or areas for improvement as well.

Include visuals to support your analysis

Visual aids can be incredibly effective in helping your audience grasp complex issues. Utilize charts, graphs, images or video clips to supplement your points. Make sure to explain each visual and how it contributes to your overall argument.

Pie charts illustrate the proportion of different components within a whole, useful for visualizing market share, budget allocation or user demographics.

This is particularly useful especially if you’re displaying survey results in your case study presentation.

Stacked charts on the other hand are perfect for visualizing composition and trends. This is great for analyzing things like customer demographics, product breakdowns or budget allocation in your case study.

Consider this example of a stacked bar chart template. It provides a straightforward summary of the top-selling cake flavors across various locations, offering a quick and comprehensive view of the data.

Not the chart you’re looking for? Browse Venngage’s gallery of chart templates to find the perfect one that’ll captivate your audience and level up your data storytelling.

Recommendations and next steps

Wrap up by providing recommendations based on the case study findings. Outline the next steps that stakeholders should take to either expand on the success of the project or address any remaining challenges.

Acknowledgments and references

Thank the people who contributed to the case study and helped in the problem-solving process. Cite any external resources, reports or data sets that contributed to your analysis.

Feedback & Q&A session

Open the floor for questions and feedback from your audience. This allows for further discussion and can provide additional insights that may not have been considered previously.

Closing remarks

Conclude the presentation by summarizing the key points and emphasizing the takeaways. Thank your audience for their time and participation and express your willingness to engage in further discussions or collaborations on the subject.

Well, the length of a case study presentation can vary depending on the complexity of the topic and the needs of your audience. However, a typical business or academic presentation often lasts between 15 to 30 minutes. 

This time frame usually allows for a thorough explanation of the case while maintaining audience engagement. However, always consider leaving a few minutes at the end for a Q&A session to address any questions or clarify points made during the presentation.

When it comes to presenting a compelling case study, having a well-structured template can be a game-changer. 

It helps you organize your thoughts, data and findings in a coherent and visually pleasing manner. 

Not all case studies are created equal and different scenarios require distinct approaches for maximum impact. 

To save you time and effort, I have curated a list of 5 versatile case study presentation templates, each designed for specific needs and audiences. 

Here are some best case study presentation examples that showcase effective strategies for engaging your audience and conveying complex information clearly.

1 . Lab report case study template

Ever feel like your research gets lost in a world of endless numbers and jargon? Lab case studies are your way out!

Think of it as building a bridge between your cool experiment and everyone else. It’s more than just reporting results – it’s explaining the “why” and “how” in a way that grabs attention and makes sense.

This lap report template acts as a blueprint for your report, guiding you through each essential section (introduction, methods, results, etc.) in a logical order.

Want to present your research like a pro? Browse our research presentation template gallery for creative inspiration!

2. Product case study template

It’s time you ditch those boring slideshows and bullet points because I’ve got a better way to win over clients: product case study templates.

Instead of just listing features and benefits, you get to create a clear and concise story that shows potential clients exactly what your product can do for them. It’s like painting a picture they can easily visualize, helping them understand the value your product brings to the table.

Grab the template below, fill in the details, and watch as your product’s impact comes to life!

3. Content marketing case study template

In digital marketing, showcasing your accomplishments is as vital as achieving them. 

A well-crafted case study not only acts as a testament to your successes but can also serve as an instructional tool for others. 

With this coral content marketing case study template—a perfect blend of vibrant design and structured documentation, you can narrate your marketing triumphs effectively.

4. Case study psychology template

Understanding how people tick is one of psychology’s biggest quests and case studies are like magnifying glasses for the mind. They offer in-depth looks at real-life behaviors, emotions and thought processes, revealing fascinating insights into what makes us human.

Writing a top-notch case study, though, can be a challenge. It requires careful organization, clear presentation and meticulous attention to detail. That’s where a good case study psychology template comes in handy.

Think of it as a helpful guide, taking care of formatting and structure while you focus on the juicy content. No more wrestling with layouts or margins – just pour your research magic into crafting a compelling narrative.

5. Lead generation case study template

Lead generation can be a real head-scratcher. But here’s a little help: a lead generation case study.

Think of it like a friendly handshake and a confident resume all rolled into one. It’s your chance to showcase your expertise, share real-world successes and offer valuable insights. Potential clients get to see your track record, understand your approach and decide if you’re the right fit.

No need to start from scratch, though. This lead generation case study template guides you step-by-step through crafting a clear, compelling narrative that highlights your wins and offers actionable tips for others. Fill in the gaps with your specific data and strategies, and voilà! You’ve got a powerful tool to attract new customers.

Related: 15+ Professional Case Study Examples [Design Tips + Templates]

So, you’ve spent hours crafting the perfect case study and are now tasked with presenting it. Crafting the case study is only half the battle; delivering it effectively is equally important. 

Whether you’re facing a room of executives, academics or potential clients, how you present your findings can make a significant difference in how your work is received. 

Forget boring reports and snooze-inducing presentations! Let’s make your case study sing. Here are some key pointers to turn information into an engaging and persuasive performance:

• Know your audience : Tailor your presentation to the knowledge level and interests of your audience. Remember to use language and examples that resonate with them.
• Rehearse : Rehearsing your case study presentation is the key to a smooth delivery and for ensuring that you stay within the allotted time. Practice helps you fine-tune your pacing, hone your speaking skills with good word pronunciations and become comfortable with the material, leading to a more confident, conversational and effective presentation.
• Start strong : Open with a compelling introduction that grabs your audience’s attention. You might want to use an interesting statistic, a provocative question or a brief story that sets the stage for your case study.
• Be clear and concise : Avoid jargon and overly complex sentences. Get to the point quickly and stay focused on your objectives.
• Use visual aids : Incorporate slides with graphics, charts or videos to supplement your verbal presentation. Make sure they are easy to read and understand.
• Tell a story : Use storytelling techniques to make the case study more engaging. A well-told narrative can help you make complex data more relatable and easier to digest.

Ditching the dry reports and slide decks? Venngage’s case study templates let you wow customers with your solutions and gain insights to improve your business plan. Pre-built templates, visual magic and customer captivation – all just a click away. Go tell your story and watch them say “wow!”

Nailed your case study, but want to make your presentation even stronger? Avoid these common mistakes to ensure your audience gets the most out of it:

Overloading with information

A case study is not an encyclopedia. Overloading your presentation with excessive data, text or jargon can make it cumbersome and difficult for the audience to digest the key points. Stick to what’s essential and impactful. Need help making your data clear and impactful? Our data presentation templates can help! Find clear and engaging visuals to showcase your findings.

Lack of structure

Jumping haphazardly between points or topics can confuse your audience. A well-structured presentation, with a logical flow from introduction to conclusion, is crucial for effective communication.

Ignoring the audience

Different audiences have different needs and levels of understanding. Failing to adapt your presentation to your audience can result in a disconnect and a less impactful presentation.

Poor visual elements

While content is king, poor design or lack of visual elements can make your case study dull or hard to follow. Make sure you use high-quality images, graphs and other visual aids to support your narrative.

Not focusing on results

A case study aims to showcase a problem and its solution, but what most people care about are the results. Failing to highlight or adequately explain the outcomes can make your presentation fall flat.

How to start a case study presentation?

Starting a case study presentation effectively involves a few key steps:

• Grab attention : Open with a hook—an intriguing statistic, a provocative question or a compelling visual—to engage your audience from the get-go.
• Set the stage : Briefly introduce the subject, context and relevance of the case study to give your audience an idea of what to expect.
• Outline objectives : Clearly state what the case study aims to achieve. Are you solving a problem, proving a point or showcasing a success?
• Agenda : Give a quick outline of the key sections or topics you’ll cover to help the audience follow along.
• Set expectations : Let your audience know what you want them to take away from the presentation, whether it’s knowledge, inspiration or a call to action.

How to present a case study on PowerPoint and on Google Slides?

Presenting a case study on PowerPoint and Google Slides involves a structured approach for clarity and impact using presentation slides :

• Title slide : Start with a title slide that includes the name of the case study, your name and any relevant institutional affiliations.
• Introduction : Follow with a slide that outlines the problem or situation your case study addresses. Include a hook to engage the audience.
• Objectives : Clearly state the goals of the case study in a dedicated slide.
• Findings : Use charts, graphs and bullet points to present your findings succinctly.
• Analysis : Discuss what the findings mean, drawing on supporting data or secondary research as necessary.
• Conclusion : Summarize key takeaways and results.
• Q&A : End with a slide inviting questions from the audience.

What’s the role of analysis in a case study presentation?

The role of analysis in a case study presentation is to interpret the data and findings, providing context and meaning to them. 

It helps your audience understand the implications of the case study, connects the dots between the problem and the solution and may offer recommendations for future action.

Is it important to include real data and results in the presentation?

Yes, including real data and results in a case study presentation is crucial to show experience,  credibility and impact. Authentic data lends weight to your findings and conclusions, enabling the audience to trust your analysis and take your recommendations more seriously

How do I conclude a case study presentation effectively?

To conclude a case study presentation effectively, summarize the key findings, insights and recommendations in a clear and concise manner. 

End with a strong call-to-action or a thought-provoking question to leave a lasting impression on your audience.

What’s the best way to showcase data in a case study presentation ?

The best way to showcase data in a case study presentation is through visual aids like charts, graphs and infographics which make complex information easily digestible, engaging and creative. 

Don’t just report results, visualize them! This template for example lets you transform your social media case study into a captivating infographic that sparks conversation.

Choose the type of visual that best represents the data you’re showing; for example, use bar charts for comparisons or pie charts for parts of a whole. 

Ensure that the visuals are high-quality and clearly labeled, so the audience can quickly grasp the key points. 

Keep the design consistent and simple, avoiding clutter or overly complex visuals that could distract from the message.

Choose a template that perfectly suits your case study where you can utilize different visual aids for maximum impact. 

Need more inspiration on how to turn numbers into impact with the help of infographics? Our ready-to-use infographic templates take the guesswork out of creating visual impact for your case studies with just a few clicks.

Related: 10+ Case Study Infographic Templates That Convert

Congrats on mastering the art of compelling case study presentations! This guide has equipped you with all the essentials, from structure and nuances to avoiding common pitfalls. You’re ready to impress any audience, whether in the boardroom, the classroom or beyond.

And remember, you’re not alone in this journey. Venngage’s Case Study Creator is your trusty companion, ready to elevate your presentations from ordinary to extraordinary. So, let your confidence shine, leverage your newly acquired skills and prepare to deliver presentations that truly resonate.

Go forth and make a lasting impact!

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• Case Interview: A comprehensive guide
• Pyramid Principle
• Hypothesis driven structure
• Fit Interview
• Consulting math
• The key to landing your consulting job
• What is a case interview?
• Types of case interview
• How to solve cases with the Problem-Driven Structure?
• What to remember in case interviews
• Case examples or building blocks?
• How do I prepare for case interviews
• Interview day tips
• How we can help

1. The key to landing your consulting job.

Case interviews - where you are asked to solve a business case study under scrutiny - are the core of the selection process right across McKinsey, Bain and BCG (the “MBB” firms). This interview format is also used pretty much universally across other high-end consultancies; including LEK, Kearney, Oliver Wyman and the consulting wings of the “Big Four”.

If you want to land a job at any of these firms, you will have to ace multiple case interviews.

It is increasingly likely that you will also have to solve online cases given by chatbots. You might need to pass these either before making it to interview or be asked to sit them alongside first round interviews.

Importantly, case studies aren’t something you can just wing . Firms explicitly expect you to have thoroughly prepared and many of your competitors on interview day will have been prepping for months.

Don’t worry though - MCC is here to help!

This article will take you through a full overview of everything you’ll need to know to do well, linking to more detailed articles and resources at each stage to let you really drill down into the details.

As well as traditional case interviews, we’ll also attend to the new formats in which cases are being delivered and otherwise make sure you’re up to speed with recent trends in this overall part of consulting recruitment.

Before we can figure out how to prepare for a case interview, though, we will first have to properly understand in detail what exactly you are up against. What format does a standard consulting case interview take? What is expected of you? How will you be assessed?

Let's dive right in and find out!

Professional help

Before going further, if this sounds like a lot to get your head around on your own, don't worry - help is available!

Our Case Academy course gives you everything you need to know to crack cases like a pro:

Case Academy Course

To put what you learn into practice (and secure some savings in the process) you can add mock interview coaching sessions with expereinced MBB consultants:

Coaching options

And, if you just want an experienced consultant to take charge of the whole selection process for you, you can check out our comprehensive mentoring programmes:

Explore mentoring

Now, back to the article!

2. What is a case interview?

Before we can hope to tackle a case interview, we have to understand what one is.

In short, a case interview simulates real consulting work by having you solve a business case study in conversation with your interviewer.

This case study will be a business problem where you have to advise a client - that is, an imaginary business or similar organisation in need of guidance.

You must help this client solve a problem and/or make a decision. This requires you to analyse the information you are given about that client organisation and figure out a final recommendation for what they should do next.

Business problems in general obviously vary in difficulty. Some are quite straightforward and can be addressed with fairly standard solutions. However, consulting firms exist precisely to solve the tough issues that businesses have failed to deal with internally - and so consultants will typically work on complex, idiosyncratic problems requiring novel solutions.

Some examples of case study questions might be:

• How much would you pay for a banking licence in Ghana?
• Estimate the potential value of the electric vehicle market in Germany
• How much gas storage capacity should a UK domestic energy supplier build?

Consulting firms need the brightest minds they can find to put to work on these important, difficult projects. You can expect the case studies you have to solve in interview, then, to echo the unique, complicated problems consultancies deal with every day. As we’ll explain here, this means that you need to be ready to think outside the box to figure out genuinely novel solutions.

2.1. Where are case interviews in the consulting selection process?

Not everyone who applies to a consulting firm will have a case interview - far from it!

In fact, case interviews are pretty expensive and inconvenient for firms to host, requiring them to take consultants off active projects and even fly them back to the office from location for in-person interviews (although this happens less frequently now). Ideally, firms want to cut costs and save time by narrowing down the candidate pool as much as possible before any live interviews.

As such, there are some hoops to jump through before you make it to interview rounds.

Firms will typically eliminate as much as 80% of the applicant pool before interviews start . For most firms, 50%+ of applicants might be cut based on resumes, before a similar cut is made on those remaining based on aptitude tests. McKinsey currently gives their Solve assessment to most applicants, but will use their resulting test scores alongside resumes to cut 70%+ of the candidate pool before interviews.

You'll need to be on top of your game to get as far as a case interview with a top firm. Getting through the resume screen and any aptitude tests is an achievement in itself! Also we need to note that the general timeline of an application can differ depending on a series of factors, including which position you apply, your background, and the office you are applying to. For example, an undergraduate applying for a Business Analyst position (the entry level job at McKinsey) will most likely be part of a recruitment cycle and as such have pretty fixed dates when they need to sit the pre-screening test, and have the first and second round interviews (see more on those below). Conversely, an experienced hire will most likely have a much greater choice of test and interview dates as well as more time at their disposal to prepare.

For readers not yet embroiled in the selection process themselves, let’s put case interviews in context and take a quick look at each stage in turn. Importantly, note that you might also be asked to solve case studies outside interviews as well…

2.1.1. Application screen

It’s sometimes easy to forget that such a large cut is made at the application stage. At larger firms, this will mean your resume and cover letter is looked at by some combination of AI tools, recruitment staff and junior consulting staff (often someone from your own university).

Only the best applications will be passed to later stages, so make sure to check out our free resume and cover letter guides, and potentially get help with editing , to give yourself the best chance possible.

2.1.2. Aptitude tests and online cases

This part of the selection process has been changing quickly in recent years and is increasingly beginning to blur into the traditionally separate case interview rounds.

In the past, GMAT or PST style tests were the norm. Firms then used increasingly sophisticated and often gamified aptitude tests, like the Pymetrics test currently used by several firms, including BCG and Bain, and the original version of McKinsey’s Solve assessment (then branded as the Problem Solving Game).

Now, though, there is a move towards delivering relatively sophisticated case studies online. For example, McKinsey has replaced half the old Solve assessment with an online case. BCG’s Casey chatbot case now directly replaces a live first round case interview, and in the new era of AI chatbots, we expect these online cases to quickly become more realistic and increasingly start to relieve firms of some of the costs of live case interviews.

Our consultants collectively reckon that, over time, 50% of case interviews are likely to be replaced with these kinds of cases . We give some specific advice for online cases in section six. However, the important thing to note is that these are still just simulations of traditional case interviews - you still need to learn how to solve cases in precisely the same way, and your prep will largely remain the same.

2.1.3. Rounds of Interviews

Now, let’s not go overboard with talk of AI. Even in the long term, the client facing nature of consulting means that firms will have live case interviews for as long as they are hiring anyone. And in the immediate term, case interviews are still absolutely the core of consulting selection.

Before landing an offer at McKinsey, Bain, BCG or any similar firm, you won’t just have one case interview, but will have to complete four to six case interviews, usually divided into two rounds, with each interview lasting approximately 50-60 minutes .

Being invited to first round usually means two or three case interviews. As noted above, you might also be asked to complete an online case or similar alongside your first round interviews.

If you ace first round, you will be invited to second round to face the same again, but more gruelling. Only then - after up to six case interviews in total, can you hope to receive an offer.

2.2. Differences between first and second round interviews

Despite case interviews in the first and second round following the same format, second/final round interviews will be significantly more intense . The seniority of the interviewer, time pressure (with up to three interviews back-to-back), and the sheer value of the job at stake will likely make a second round consulting case interview one of the most challenging moments of your professional life.

There are three key differences between the two rounds:

• Time Pressure : Final round case interviews test your ability to perform under pressure, with as many as three interviews in a row and often only very small breaks between them.
• Focus : Since second round interviewers tend to be more senior (usually partners with 12+ years experience) and will be more interested in your personality and ability to handle challenges independently. Some partners will drill down into your experiences and achievements to the extreme. They want to understand how you react to challenges and your ability to identify and learn from past mistakes.
• Psychological Pressure: While case interviews in the first round are usually more focused on you simply cracking the case, second round interviewers often employ a "bad cop" strategy to test the way you react to challenges and uncertainty.

2.3. What skills do case interviews assess?

Reliably impressing your interviewers means knowing what they are looking for. This means understanding the skills you are being assessed against in some detail.

Overall, it’s important always to remember that, with case studies, there are no strict right or wrong answers. What really matters is how you think problems through, how confident you are with your conclusions and how quick you are with the back of the envelope arithmetic.

The objective of this kind of interview isn’t to get to one particular solution, but to assess your skillset. This is even true of modern online cases, where sophisticated AI algorithms score how you work as well as the solutions you generate.

If you visit McKinsey , Bain and BCG web pages on case interviews, you will find that the three firms look for very similar traits, and the same will be true of other top consultancies.

Broadly speaking, your interviewer will be evaluating you across five key areas:

2.1.1.One: Probing mind

Showing intellectual curiosity by asking relevant and insightful questions that demonstrate critical thinking and a proactive nature. For instance, if we are told that revenues for a leading supermarket chain have been declining over the last ten years, a successful candidate would ask:

“ We know revenues have declined. This could be due to price or volume. Do we know how they changed over the same period? ”

This is as opposed to a laundry list of questions like:

• Did customers change their preferences?
• Which segment has shown the decline in volume?
• Is there a price war in the industry?

2.1.2. Structure

Structure in this context means structuring a problem. This, in turn, means creating a framework - that is, a series of clear, sequential steps in order to get to a solution.

As with the case interview in general, the focus with case study structures isn’t on reaching a solution, but on how you get there.

This is the trickiest part of the case interview and the single most common reason candidates fail.

We discuss how to properly structure a case in more detail in section three. In terms of what your interviewer is looking for at high level, though, key pieces of your structure should be:

• Proper understanding of the objective of the case - Ask yourself: "What is the single crucial piece of advice that the client absolutely needs?"
• Identification of the drivers - Ask yourself: "What are the key forces that play a role in defining the outcome?"

Our Problem Driven Structure method, discussed in section three, bakes this approach in at a fundamental level. This is as opposed to the framework-based approach you will find in older case-solving

Focus on going through memorised sequences of steps too-often means failing to develop a full understanding of the case and the real key drivers.

At this link, we run through a case to illustrate the difference between a standard framework-based approach and our Problem Driven Structure method.

2.1.3. Problem Solving

You’ll be tested on your ability to identify problems and drivers, isolate causes and effects, demonstrate creativity and prioritise issues. In particular, the interviewer will look for the following skills:

• Prioritisation - Can you distinguish relevant and irrelevant facts?
• Connecting the dots - Can you connect new facts and evidence to the big picture?
• Establishing conclusions - Can you establish correct conclusions without rushing to inferences not supported by evidence?

2.1.4. Numerical Agility

In case interviews, you are expected to be quick and confident with both precise and approximated numbers. This translates to:

• Performing simple calculations quickly - Essential to solve cases quickly and impress clients with quick estimates and preliminary conclusions.
• Analysing data - Extract data from graphs and charts, elaborate and draw insightful conclusions.
• Solving business problems - Translate a real world case to a mathematical problem and solve it.

Our article on consulting math is a great resource here, though the extensive math content in our MCC Academy is the best and most comprehensive material available.

2.1.5. Communication

Real consulting work isn’t just about the raw analysis to come up with a recommendation - this then needs to be sold to the client as the right course of action.

Similarly, in a case interview, you must be able to turn your answer into a compelling recommendation. This is just as essential to impressing your interviewer as your structure and analysis.

Consultants already comment on how difficult it is to find candidates with the right communication skills. Add to this the current direction of travel, where AI will be able to automate more and more of the routine analytic side of consulting, and communication becomes a bigger and bigger part of what consultants are being paid for.

So, how do you make sure that your recommendations are relevant, smart, and engaging? The answer is to master what is known as CEO-level communication .

This art of speaking like a CEO can be quite challenging, as it often involves presenting information in effectively the opposite way to how you might normally.

To get it right, there are three key areas to focus on in your communications:

• Top down : A CEO wants to hear the key message first. They will only ask for more details if they think that will actually be useful. Always consider what is absolutely critical for the CEO to know, and start with that. You can read more in our article on the Pyramid Principle .
• Concise : This is not the time for "boiling the ocean" or listing an endless number possible solutions. CEOs, and thus consultants, want a structured, quick and concise recommendation for their business problem, that they can implement immediately.
• Fact-based : Consultants share CEOs' hatred of opinions based on gut feel rather than facts. They want recommendations based on facts to make sure they are actually in control. Always go on to back up your conclusions with the relevant facts.

Being concise and to the point is key in many areas, networking being one for them. For more detail on all this, check out our full article on delivering recommendations .

Prep the right way

3. types of case interview.

While most case interviews share a similar structure, firms will have some differences in the particular ways they like to do things in terms of both the case study and the fit component.

As we’ll see, these differences aren’t hugely impactful in terms of how you prepare. That said, it's always good to know as much as possible about what you will be going up against.

3.1. Different case objectives

A guiding thread throughout this article and our approach in general will be to treat each case as a self-contained problem and not try to pigeonhole it into a certain category. Having said that, there are of course similarities between cases and we can identify certain parameters and objectives.

Broadly speaking, cases can be divided into issue-based cases and strategic decision cases. In the former you will be asked to solve a certain issue, such as declining profits, or low productivity whereas in the latter you will be ask whether your client should or should not do something, such as enter a specific market or acquire another company. The chart below is a good breakdown of these different objectives:

3.2. How do interviewers craft cases

While interviewers will very likely be given a case bank to choose from by their company, a good number of them will also choose to adapt the cases they would currently be working on to a case interview setting. The difference is that the latter cases will be harder to pigeonhole and apply standard frameworks to, so a tailored approach will be paramount.

If you’ve applied for a specific practice or type of consulting - such as operational consulting, for example - it’s very likely that you will receive a case geared towards that particular area alongside a ‘generalist’ consulting case (however, if that’s the case, you will generally be notified). The other main distinction when it comes to case interviews is between interviewer-led and candidate-led.

3.3. Candidate-led cases

Most consulting case interview questions test your ability to crack a broad problem, with a case prompt often going something like:

" How much would you pay to secure the rights to run a restaurant in the British Museum? "

You, as a candidate, are then expected to identify your path to solve the case (that is, provide a structure), leveraging your interviewer to collect the data and test your assumptions.

This is known as a “candidate-led” case interview and is used by Bain, BCG and other firms. From a structuring perspective, it’s easier to lose direction in a candidate-led case as there are no sign-posts along the way. As such, you need to come up with an approach that is both broad enough to cover all of the potential drivers in a case but also tailored enough to the problem you are asked to solve. It’s also up to you to figure out when you need to delve deeper into a certain branch of the case, brainstorm or ask for data. The following case from Bain is an excellent example on how to navigate a candidate-led case.

3.4. Interviewer-led cases

This type of case - employed most famously by McKinsey - is slightly different, with the interviewer controlling the pace and direction of the conversation much more than with other case interviews.

At McKinsey, your interviewer will ask you a set of pre-determined questions, regardless of your initial structure. For each question, you will have to understand the problem, come up with a mini structure, ask for additional data (if necessary) and come to the conclusion that answers the question. This more structured format of case also shows up in online cases by other firms - notably including BCG’s Casey chatbot (with the amusing result that practising McKinsey-style cases can be a great addition when prepping for BCG).

Essentially, these interviewer-led case studies are large cases made up of lots of mini-cases. You still use basically the same method as you would for standard (or candidate-led) cases - the main difference is simply that, instead of using that method to solve one big case, you are solving several mini-cases sequentially. These cases are easier to follow as the interviewer will guide you in the right direction. However, this doesn’t mean you should pay less attention to structure and deliver a generic framework! Also, usually (but not always!) the first question will ask you to map your approach and is the equivalent of the structuring question in candidate-led cases. Sometimes, if you’re missing key elements, the interviewer might prompt you in the right direction - so make sure to take those prompts seriously as they are there to help you get back on track (ask for 30 seconds to think on the prompt and structure your approach). Other times - and this is a less fortunate scenario - the interviewer might say nothing and simply move on to the next question. This is why you should put just as much thought (if not more) into the framework you build for interviewer-led cases , as you may be penalized if you produce something too generic or that doesn’t encompass all the issues of the case.

3.5. Case and fit

The standard case interview can be thought of as splitting into two standalone sub-interviews. Thus “case interviews” can be divided into the case study itself and a “fit interview” section, where culture fit questions are asked.

This can lead to a bit of confusion, as the actual case interview component might take up as little as half of your scheduled “case interview”. You need to make sure you are ready for both aspects.

To illustrate, here is the typical case interview timeline:

• First 15-30 minutes: Fit Interview - with questions assessing your motivation to be a consultant in that specific firm and your traits around leadership and teamwork. Learn more about the fit interview in our in-depth article here .
• Next 30-40 minutes: Case Interview - solving a case study
• Last 5 minutes: Fit Interview again - this time focussing on your questions for your interviewer.

Both the Case and Fit interviews play crucial roles in the finial hiring decision. There is no “average” taken between case and fit interviews: if your performance is not up to scratch in either of the two, you will not be able to move on to the next interview round or get an offer.

NB: No case without fit

Note that, even if you have only been told you are having a case interview or otherwise are just doing a case study, always be prepared to answer fit questions. At most firms, it is standard practice to include some fit questions in all case interviews, even if there are also separate explicit fit interviews, and interviewers will almost invariably include some of these questions around your case. This is perfectly natural - imagine how odd and artificial it would be to show up to an interview, simply do a case and leave again, without talking about anything else with the interviewer before or after.

3.5.1 Differences between firms

For the most part, a case interview is a case interview. However, firms will have some differences in the particular ways they like to do things in terms of both the case study and the fit component.

3.5.2. The McKinsey PEI

McKinsey brands its fit aspect of interviews as the Personal Experience Interview or PEI. Despite the different name, this is really much the same interview you will be going up against in Bain, BCG and any similar firms.

McKinsey does have a reputation for pushing candidates a little harder with fit or PEI questions , focusing on one story per interview and drilling down further into the specific details each time. We discuss this tendency more in our fit interview article . However, no top end firm is going to go easy on you and you should absolutely be ready for the same level of grilling at Bain, BCG and others. Thus any difference isn’t hugely salient in terms of prep.

3.6. What is different in 2023?

For the foreseeable future, you are going to have to go through multiple live case interviews to secure any decent consulting job. These might increasingly happen via Zoom rather than in person, but they should remain largely the same otherwise.

However, things are changing and the rise of AI in recent months seems pretty much guaranteed to accelerate existing trends.

Even before the explosive development of AI chatbots like ChatGPT we have seen in recent months, automation was already starting to change the recruitment process.

As we mentioned, case interviews are expensive and inconvenient for firms to run . Ideally, then, firms will try to reduce the number of interviews required for recruitment as far as possible. For many years, tests of various kinds served to cut down the applicant pool and thus the number of interviews. However, these tests had a limited capacity to assess candidates against the full consulting skillset in the way that case interviews do so well.

More recently, though, the development of online testing has allowed for more and more advanced assessments. Top consulting firms have been leveraging screening tests that better and better capture the same skillset as case interviews. Eventually this is converging on automated case studies. We see this very clearly with the addition of the Redrock case to McKinsey’s Solve assessment.

As these digital cases become closer to the real thing, the line between test and case interview blurs. Online cases don’t just reduce the number of candidates to case interview, but start directly replacing them.

Case in point here is BCG’s Casey chatbot . Previously, BCG had deployed less advanced online cases and similar tests to weed out some candidates before live case interviews began. Now, though, Casey actually replaces one first round case interview.

Casey, at time of writing, is still a relatively “basic” chatbot, basically running through a pre-set script. The Whatsapp-like interface does a lot of work to make it feel like one is chatting to a “real person” - the chatbot itself, though, cannot provide feedback or nudges to candidates as would a human interviewer.

We fully expect that, as soon as BCG and other firms can train a truer AI, these online cases will become more widespread and start replacing more live interviews.

We discuss the likely impacts of advanced AI on consulting recruitment and the industry more broadly in our blog.

Here, though, the real message is that you should expect to run into digital cases as well as traditional case interviews.

Luckily, despite any changes in specific case interview format, you will still need to master the same fundamental skills and prepare in much the same way.

We’ll cover a few ways to help prepare for chatbot cases in section four. Ultimately, though, firms are looking for the same problem solving ability and mindset as a real interviewer. Especially as chatbots get better at mimicking a real interviewer, candidates who are well prepared for case cracking in general should have no problem with AI administered cases.

3.6.1. Automated fit interviews

Analogous to online cases, in recent years there has been a trend towards automated, “one way” fit interviews, with these typically being administered for consultancies by specialist contractors like HireVue or SparkHire.

These are kind of like Zoom interviews, but if the interviewer didn’t show up. Instead you will be given fit questions to answer and must record your answer in your computer webcam. Your response will then go on to be assessed by an algorithm, scoring both what you say and how you say it.

Again, with advances in AI, it is easy to imagine these automated case interviews going from fully scripted interactions, where all candidates are asked the same list of questions, to a more interactive experience. Thus, we might soon arrive at a point where you are being grilled on the details of your stories - McKinsey PEI style - but by a bot rather than a human.

We include some tips on this kind of “one way” fit interview in section six here.

4. How to solve cases with the Problem-Driven Structure?

If you look around online for material on how to solve case studies, a lot of what you find will set out framework-based approaches. However, as we have mentioned, these frameworks tend to break down with more complex, unique cases - with these being exactly the kind of tough case studies you can expect to be given in your case interviews.

To address this problem, the MyConsultingCoach team has synthesized a new approach to case cracking that replicates how top management consultants approach actual engagements.

MyConsultingCoach’s Problem Driven Structure approach is a universal problem solving method that can be applied to any business problem , irrespective of its nature.

As opposed to just selecting a generic framework for each case interview, the Problem Driven Structure approach works by generating a bespoke structure for each individual question and is a simplified version of the roadmap McKinsey consultants use when working on engagements.

The canonical seven steps from McKinsey on real projects are simplified to four for case interview questions, as the analysis required for a six-month engagement is somewhat less than that needed for a 45-minute case study. However, the underlying flow is the same (see the method in action in the video below)

Let's zoom in to see how our method actually works in more detail:

4.1. Identify the problem

Identifying the problem means properly understanding the prompt/question you are given, so you get to the actual point of the case.

This might sound simple, but cases are often very tricky, and many candidates irretrievably mess things up within the first few minutes of starting. Often, they won’t notice this has happened until they are getting to the end of their analysis. Then, they suddenly realise that they have misunderstood the case prompt - and have effectively been answering the wrong question all along!

With no time to go back and start again, there is nothing to do. Even if there were time, making such a silly mistake early on will make a terrible impression on their interviewer, who might well have written them off already. The interview is scuppered and all the candidate’s preparation has been for nothing.

This error is so galling as it is so readily avoidable.

Our method prevents this problem by placing huge emphasis on a full understanding of the case prompt. This lays the foundations for success as, once we have identified the fundamental, underlying problem our client is facing, we focus our whole analysis around finding solutions to this specific issue.

Now, some case interview prompts are easy to digest. For example, “Our client, a supermarket, has seen a decline in profits. How can we bring them up?”. However, many of the prompts given in interviews for top firms are much more difficult and might refer to unfamiliar business areas or industries. For example, “How much would you pay for a banking license in Ghana?” or “What would be your key areas of concern be when setting up an NGO?”

Don’t worry if you have no idea how you might go about tackling some of these prompts!

In our article on identifying the problem and in our full lesson on the subject in our MCC Academy course, we teach a systematic, four step approach to identifying the problem , as well as running through common errors to ensure you start off on the right foot every time!

This is summarised here:

Following this method lets you excel where your competitors mess up and get off to a great start in impressing your interviewer!

4.2. Build your problem driven structure

After you have properly understood the problem, the next step is to successfully crack a case is to draw up a bespoke structure that captures all the unique features of the case.

This is what will guide your analysis through the rest of the case study and is precisely the same method used by real consultants working on real engagements.

Of course, it might be easier here to simply roll out one an old-fashioned framework, and a lot of candidates will do so. This is likely to be faster at this stage and requires a lot less thought than our problem-driven structure approach.

However, whilst our problem driven structure approach requires more work from you, our method has the advantage of actually working in the kind of complex case studies where generic frameworks fail - that is exactly the kind of cases you can expect at an MBB interview .

Since we effectively start from first principles every time, we can tackle any case with the same overarching method. Simple or complex, every case is the same to you and you don’t have to gamble a job on whether a framework will actually work

4.2.1 Issue trees

Issue trees break down the overall problem into a set of smaller problems that you can then solve individually. Representing this on a diagram also makes it easy for both you and your interviewer to keep track of your analysis.

To see how this is done, let’s look at the issue tree below breaking down the revenues of an airline:

These revenues can be segmented as the number of customers multiplied by the average ticket price. The number of customers can be further broken down into a number of flights multiplied by the number of seats, times average occupancy rate. The node corresponding to the average ticket price can then be segmented further.

4.2.2 Hypothesis trees

Hypothesis trees are similar, the only difference being that rather than just trying to break up the issue into smaller issues you are assuming that the problem can be solved and you are formulating solutions.

In the example above, you would assume revenues can be increased by either increasing the average ticket price or the number of customers . You can then hypothesize that you can increase the average occupancy rate in three ways: align the schedule of short and long haul flights, run a promotion to boost occupancy in off-peak times, or offer early bird discounts.

4.2.3 Other structures:structured lists

Structured lists are simply subcategories of a problem into which you can fit similar elements. This McKinsey case answer starts off by identifying several buckets such as retailer response, competitor response, current capabilities and brand image and then proceeds to consider what could fit into these categories.

Buckets can be a good way to start the structure of a complex case but when using them it can be very difficult to be MECE and consistent, so you should always aim to then re-organize them into either an issue or a hypothesis tree.

It is worth noting that the same problem can be structured in multiple valid ways by choosing different means to segment the key issues. Ultimately all these lists are methods to set out a logical hierachy among elements.

4.2.4 Structures in practice

That said, not all valid structures are equally useful in solving the underlying problem. A good structure fulfils several requirements - including MECE-ness , level consistency, materiality, simplicity, and actionability. It’s important to put in the time to master segmentation, so you can choose a scheme isn’t only valid, but actually useful in addressing the problem.

After taking the effort to identify the problem properly, an advantage of our method is that it will help ensure you stay focused on that same fundamental problem throughout. This might not sound like much, but many candidates end up getting lost in their own analysis, veering off on huge tangents and returning with an answer to a question they weren’t asked.

Another frequent issue - particularly with certain frameworks - is that candidates finish their analysis and, even if they have successfully stuck to the initial question, they have not actually reached a definite solution. Instead, they might simply have generated a laundry list of pros and cons, with no clear single recommendation for action.

Clients employ consultants for actionable answers, and this is what is expected in the case interview. The problem driven structure excels in ensuring that everything you do is clearly related back to the key question in a way that will generate a definitive answer. Thus, the problem driven structure builds in the hypothesis driven approach so characteristic of real consulting practice.

You can learn how to set out your own problem driven structures in our article here and in our full lesson in the MCC Academy course.

4.2. Lead the analysis

A problem driven structure might ensure we reach a proper solution eventually, but how do we actually get there?

We call this step " leading the analysis ", and it is the process whereby you systematically navigate through your structure, identifying the key factors driving the issue you are addressing.

Generally, this will mean continuing to grow your tree diagram, further segmenting what you identify as the most salient end nodes and thus drilling down into the most crucial factors causing the client’s central problem.

Once you have gotten right down into the detail of what is actually causing the company’s issues, solutions can then be generated quite straightforwardly.

To see this process in action, we can return to our airline revenue example:

Let’s say we discover the average ticket price to be a key issue in the airline’s problems. Looking closer at the drivers of average ticket price, we find that the problem lies with economy class ticket prices. We can then further segment that price into the base fare and additional items such as food.

Having broken down the issue to such a fine-grained level and considering the 80/20 rule(see below), solutions occur quite naturally. In this case, we can suggest incentivising the crew to increase onboard sales, improving assortment in the plane, or offering discounts for online purchases.

Our article on leading the analysis is a great primer on the subject, with our video lesson in the MCC Academy providing the most comprehensive guide available.

4.4. Provide recommendations

So you have a solution - but you aren’t finished yet!

Now, you need to deliver your solution as a final recommendation.

This should be done as if you are briefing a busy CEO and thus should be a one minute, top-down, concise, structured, clear, and fact-based account of your findings.

The brevity of the final recommendation belies its importance. In real life consulting, the recommendation is what the client has potentially paid millions for - from their point of view, it is the only thing that matters.

In a case interview, your performance in this final summing up of your case is going to significantly colour your interviewer’s parting impression of you - and thus your chances of getting hired!

So, how do we do it right?

Barbara Minto's Pyramid Principle elegantly sums up almost everything required for a perfect recommendation. The answer comes first , as this is what is most important. This is then supported by a few key arguments , which are in turn buttressed by supporting facts .

Across the whole recommendation, the goal isn’t to just summarise what you have done. Instead, you are aiming to synthesize your findings to extract the key "so what?" insight that is useful to the client going forward.

All this might seem like common sense, but it is actually the opposite of how we relay results in academia and other fields. There, we typically move from data, through arguments and eventually to conclusions. As such, making good recommendations is a skill that takes practice to master.

We can see the Pyramid Principle illustrated in the diagram below:

To supplement the basic Pyramid Principle scheme, we suggest candidates add a few brief remarks on potential risks and suggested next steps . This helps demonstrate the ability for critical self-reflection and lets your interviewer see you going the extra mile.

The combination of logical rigour and communication skills that is so definitive of consulting is particularly on display in the final recommendation.

Despite it only lasting 60 seconds, you will need to leverage a full set of key consulting skills to deliver a really excellent recommendation and leave your interviewer with a good final impression of your case solving abilities.

Our specific article on final recommendations and the specific video lesson on the same topic within our MCC Academy are great, comprehensive resources. Beyond those, our lesson on consulting thinking and our articles on MECE and the Pyramid Principle are also very useful.

4.5. What if I get stuck?

Naturally with case interviews being difficult problems there may be times where you’re unsure what to do or which direction to take. The most common scenario is that you will get stuck midway through the case and there are essentially two things that you should do:

• 1. Go back to your structure
• 2. Ask the interviewer for clarification

Your structure should always be your best friend - after all, this is why you put so much thought and effort into it: if it’s MECE it will point you in the right direction. This may seem abstract but let’s take the very simple example of a profitability case interview: if you’ve started your analysis by segmenting profit into revenue minus costs and you’ve seen that the cost side of the analysis is leading you nowhere, you can be certain that the declining profit is due to a decline in revenue.

Similarly, when you’re stuck on the quantitative section of the case interview, make sure that your framework for calculations is set up correctly (you can confirm this with the interviewer) and see what it is you’re trying to solve for: for example if you’re trying to find what price the client should sell their new t-shirt in order to break even on their investment, you should realize that what you’re trying to find is the break even point, so you can start by calculating either the costs or the revenues. You have all the data for the costs side and you know they’re trying to sell 10.000 pairs so you can simply set up the equation with x being the price.

As we’ve emphasised on several occasions, your case interview will be a dialogue. As such, if you don’t know what to do next or don’t understand something, make sure to ask the interviewer (and as a general rule always follow their prompts as they are trying to help, not trick you). This is especially true for the quantitative questions, where you should really understand what data you’re looking at before you jump into any calculations. Ideally you should ask your questions before you take time to formulate your approach but don’t be afraid to ask for further clarification if you really can’t make sense of what’s going on. It’s always good to walk your interviewer through your approach before you start doing the calculations and it’s no mistake to make sure that you both have the same understanding of the data. For example when confronted with the chart below, you might ask what GW (in this case gigawatt) means from the get-go and ask to confirm the different metrics (i.e. whether 1 GW = 1000 megawatts). You will never be penalised for asking a question like that.

5. What to remember in case interviews

If you’re new to case cracking you might feel a bit hopeless when you see a difficult case question, not having any idea where to start.

In fact though, cracking case interviews is much like playing chess. The rules you need to know to get started are actually pretty simple. What will make you really proficient is time and practice.

In this section, we’ll run through a high level overview of everything you need to know, linking to more detailed resources at every step.

5.1. An overall clear structure

You will probably hear this more than you care for but it is the most important thing to keep in mind as you start solving cases, as not only it is a key evaluation criterion but the greatest tool you will have at your disposal. The ability to build a clear structure in all aspects of the case inteview will be the difference between breezing through a complicated case and struggling at its every step. Let’s look a bit closer at the key areas where you should be structured!

5.1.1 Structured notes

Every case interview starts with a prompt, usually verbal, and as such you will have to take some notes. And here is where your foray into structure begins, as the notes you take should be clear, concise and structured in a way that will allow you to repeat the case back to the interviewer without writing down any unnecessary information.

This may sound very basic but you should absolutely not be dismissive about it: taking clear and organized notes will allow what we found helps is to have separate sections for:

• The case brief
• Follow-up questions and answers
• Numerical data
• Case structure (the most crucial part when solving the case)
• Any scrap work during the case (usually calculations)

When solving the case - or, as we call it here, in the Lead the analysis step, it is highly recommended to keep on feeding and integrating your structure, so that you never get lost. Maintaining a clear high level view is one of the most critical aspects in case interviews as it is a key skill in consulting: by constantly keeping track of where you are following your structure, you’ll never lose your focus on the end goal.

In the case of an interviewer-led case, you can also have separate sheets for each question (e.g. Question 1. What factors can we look at that drive profitability?). If you develop a system like this you’ll know exactly where to look for each point of data rather than rummage around in untidy notes. There are a couple more sections that you may have, depending on preference - we’ll get to these in the next sections.

5.1.2 Structured communication

There will be three main types of communication in cases:

• 1. Asking and answering questions
• 2. Walking the interviewer through your structure (either the case or calculation framework - we’ll get to that in a bit!)
• 3. Delivering your recommendation

Asking and answering questions will be the most common of these and the key thing to do before you speak is ask for some time to collect your thoughts and get organised. What you want to avoid is a ‘laundry list’ of questions or anything that sounds too much like a stream of consciousness.

Different systems work for different candidates but a sure-fire way of being organised is numbering your questions and answers. So rather than saying something like ‘I would like to ask about the business model, operational capacity and customer personas’ it’s much better to break it down and say something along the lines of ‘I’ve got three key questions. Firstly I would like to inquire into the business model of our client. Secondly I would like to ask about their operational capacity. Thirdly I would like to know more about the different customer personas they are serving’.

A similar principle should be applied when walking the interviewer through your structure, and this is especially true of online case interviews (more and more frequent now) when the interviewer can’t see your notes. Even if you have your branches or buckets clearly defined, you should still use a numbering system to make it obvious to the interviewer. So, for example, when asked to identify whether a company should make an acquisition, you might say ‘I would like to examine the following key areas. Firstly the financial aspects of this issue, secondly the synergies and thirdly the client’s expertise’

The recommendation should be delivered top-down (see section 4.4 for specifics) and should employ the same numbering principle. To do so in a speedy manner, you should circle or mark the key facts that you encounter throughout the case so you can easily pull them out at the end.

5.1.3 Structured framework

It’s very important that you have a systematic approach - or framework - for every case. Let’s get one thing straight: there is a difference between having a problem-solving framework for your case and trying to force a case into a predetermined framework. Doing the former is an absolute must , whilst doing the latter will most likely have you unceremoniously dismissed.

We have seen there are several ways of building a framework, from identifying several categories of issues (or ‘buckets’) to building an issue or hypothesis tree (which is the most efficient type of framework). For the purpose of organization, we recommend having a separate sheet for the framework of the case, or, if it’s too much to manage, you can have it on the same sheet as the initial case prompt. That way you’ll have all the details as well as your proposed solution in one place.

5.1.4 Structured calculations

Whether it’s interviewer or candidate-led, at some point in the case you will get a bunch of numerical data and you will have to perform some calculations (for the specifics of the math you’ll need on consulting interviews, have a look at our Consulting Math Guide ). Here’s where we urge you to take your time and not dive straight into calculating! And here’s why: while your numerical agility is sure to impress interviewers, what they’re actually looking for is your logic and the calculations you need to perform in order to solve the problem . So it’s ok if you make a small mistake, as long as you’re solving for the right thing.

As such, make it easy for them - and yourself. Before you start, write down in steps the calculations you need to perform. Here’s an example: let’s say you need to find out by how much profits will change if variable costs are reduced by 10%. Your approach should look something like:

• 1. Calculate current profits: Profits = Revenues - (Variable costs + Fixed costs)
• 2. Calculate the reduction in variable costs: Variable costs x 0.9
• 3. Calculate new profits: New profits = Revenues - (New variable costs + Fixed costs)

Of course, there may be more efficient ways to do that calculation, but what’s important - much like in the framework section - is to show your interviewer that you have a plan, in the form of a structured approach. You can write your plan on the sheet containing the data, then perform the calculations on a scrap sheet and fill in the results afterward.

5.2. Common business knowledge and formulas

Although some consulting firms claim they don’t evaluate candidates based on their business knowledge, familiarity with basic business concepts and formulae is very useful in terms of understanding the case studies you are given in the first instance and drawing inspiration for structuring and brainstorming.

If you are coming from a business undergrad, an MBA or are an experienced hire, you might well have this covered already. For those coming from a different background, it may be useful to cover some.

Luckily, you don’t need a degree-level understanding of business to crack case interviews , and a lot of the information you will pick up by osmosis as you read through articles like this and go through cases.

However, some things you will just need to sit down and learn. We cover everything you need to know in some detail in our Case Academy Course course. However, some examples here of things you need to learn are:

• Basic accounting (particularly how to understand all the elements of a balance sheet)
• Basic economics
• Basic marketing
• Basic strategy

Below we include a few elementary concepts and formulae so you can hit the ground running in solving cases. We should note that you should not memorise these and indeed a good portion of them can be worked out logically, but you should have at least some idea of what to expect as this will make you faster and will free up much of your mental computing power. In what follows we’ll tackle concepts that you will encounter in the private business sector as well as some situations that come up in cases that feature clients from the NGO or governmental sector.

5.2.1 Business sector concepts

These concepts are the bread and butter of almost any business case so you need to make sure you have them down. Naturally, there will be specificities and differences between cases but for the most part here is a breakdown of each of them.

5.2.1.1. Revenue

The revenue is the money that the company brings in and is usually equal to the number of products they sell multiplied to the price per item and can be expressed with the following equation:

Revenue = Volume x Price

Companies may have various sources of revenue or indeed multiple types of products, all priced differently which is something you will need to account for in your case interview. Let’s consider some situations. A clothing company such as Nike will derive most of their revenue from the number of products they sell times the average price per item. Conversely, for a retail bank revenue is measured as the volume of loans multiplied by the interest rate at which the loans are given out. As we’ll see below, we might consider primary revenues and ancillary revenues: in the case of a football club, we might calculate primary revenues by multiplying the number of tickets sold by the average ticket price, and ancillary revenues those coming from sales of merchandise (similarly, let’s say average t-shirt price times the number of t-shirts sold), tv rights and sponsorships.

These are but a few examples and another reminder that you should always aim to ask questions and understand the precise revenue structure of the companies you encounter in cases.

5.2.1.2. Costs

The costs are the expenses that a company incurs during its operations. Generally, they can be broken down into fixed and variable costs :

Costs = Fixed Costs + Variable Costs

As their name implies, fixed costs do not change based on the number of units produced or sold. For example, if you produce shoes and are renting the space for your factory, you will have to pay the rent regardless of whether you produce one pair or 100. On the other hand, variable costs depend on the level of activity, so in our shoe factory example they would be equivalent to the materials used to produce each pair of shoes and would increase the more we produce.

These concepts are of course guidelines used in order to simplify the analysis in cases, and you should be aware that in reality often the situation can be more complicated. However, this should be enough for case interviews. Costs can also be quasi-fixed, in that they increase marginally with volume. Take the example of a restaurant which has a regular staff, incurring a fixed cost but during very busy hours or periods they also employ some part-time workers. This cost is not exactly variable (as it doesn’t increase with the quantity of food produced) but also not entirely fixed, as the number of extra hands will depend on how busy the restaurant is. Fixed costs can also be non-linear in nature. Let’s consider the rent in the same restaurant: we would normally pay a fixed amount every month, but if the restaurant becomes very popular we might need to rent out some extra space so the cost will increase. Again, this is not always relevant for case interviews.

5.2.1.3. Profit and profit margin

The profit is the amount of money a company is left with after it has paid all of its expenses and can be expressed as follows:

Profit = Revenue - Costs

It’s very likely that you will encounter a profitability issue in one of your case interviews, namely you will be asked to increase a company’s profit. There are two main ways of doing this: increasing revenues and reducing costs , so these will be the two main areas you will have to investigate. This may seem simple but what you will really need to understand in a case are the key drivers of a business (and this should be done through clarifying questions to the interviewer - just as a real consultant would question their client).

For example, if your client is an airline you can assume that the main source of revenue is sales of tickets, but you should inquire how many types of ticket the specific airline sells. You may naturally consider economy and business class tickets, but you may find out that there is a more premium option - such as first class - and several in-between options. Similarly to our football club example, there may be ancillary revenues from selling of food and beverage as well as advertising certain products or services on flights.

You may also come across the profit margin in case interviews. This is simply the percentage of profit compared to the revenue and can be expressed as follows:

Profit margin = Profit/Revenue x 100

5.2.1.4. Break-even point

An ancillary concept to profit, the break-even point is the moment where revenues equal costs making the profit zero and can be expressed as the following equation:

Revenues = Costs (Fixed costs + Variable costs)

This formula will be useful when you are asked questions such as ‘What is the minimum price I should sell product X?’ or ‘What quantity do I need to sell in order to recoup my investment?’. Let’s say in a case interview an owner of a sandwich store asks us to figure out how many salami and cheese salami sandwiches she needs to sell in order to break even. She’s spending $4 on salami and $2 for cheese and lettuce per sandwich, and believes she can sell the sandwiches at around $7. The cost of utilities and personnel is around $5000 per month. We could lay this all out in the break-even equation:

7 x Q ( quantity ) = (4+2) x Q + 5000 ( variable + fixed costs )

In a different scenario, we may be asked to calculate the break-even price . Let’s consider our sandwich example and say our owner knows she has enough ingredients for about 5000 sandwiches per month but is not sure how much to sell them for. In that case, if we know our break-even equation, we can simply make the following changes:

P ( price ) x 5000 = (4+2) x 5000 + 5000

By solving the equation we get to the price of $7 per sandwich.

5.2.1.5. Market share and market size

We can also consider the market closely with profit, as in fact the company’s performance in the market is what drives profits. The market size is the total number of potential customers for a certain business or product, whereas the market share is the percentage of that market that your business controls (or could control, depending on the case).

There is a good chance you will have to estimate the market size in one of your case interviews and we get into more details on how to do that below. You may be asked to estimate this in either number of potential customers or total value . The latter simply refers to the number of customers multiplied by the average value of the product or service.

To calculate the market share you will have to divide the company’s share by the total market size and multiply by 100:

Note, though, that learning the very basics of business is the beginning rather than the end of your journey. Once you are able to “speak business” at a rudimentary level, you should try to “become fluent” and immerse yourself in reading/viewing/listening to as wide a variety of business material as possible, getting a feel for all kinds of companies and industries - and especially the kinds of problems that can come up in each context and how they are solved. The material put out by the consulting firms themselves is a great place to start, but you should also follow the business news and find out about different companies and sectors as much as possible between now and interviews. Remember, if you’re going to be a consultant, this should be fun rather than a chore!

5.3 Public sector and NGO concepts

As we mentioned, there will be some cases (see section 6.6 for a more detailed example) where the key performance indicators (or KPIs in short) will not be connected to profit. The most common ones will involve the government of a country or an NGO, but they can be way more diverse and require more thought and application of first principles. We have laid out a couple of the key concepts or KPIs that come up below

5.3.1 Quantifiability

In many such scenarios you will be asked to make an important strategic decision of some kind or to optimise a process. Of course these are not restricted to non-private sector cases but this is where they really come into their own as there can be great variation in the type of decision and the types of field.

While there may be no familiar business concepts to anchor yourself onto, a concept that is essential is quantifiability . This means, however qualitative the decision might seem, consultants rely on data so you should always aim to have aspects of a decision that can be quantified, even if the data doesn’t present itself in a straightforward manner.

Let’s take a practical example. Your younger sibling asks you to help them decide which university they should choose if they want to study engineering. One way to structure your approach would be to segment the problem into factors affecting your sibling’s experience at university and experience post-university. Within the ‘at uni’ category you might think about the following:

• Financials : How much are tuition costs and accommodation costs?
• Quality of teaching and research : How are possible universities ranked in the QS guide based on teaching and research?
• Quality of resources : How well stocked is their library, are the labs well equipped etc.?
• Subject ranking : How is engineering at different unis ranked?
• Life on campus and the city : What are the living costs in the city where the university is based? What are the extracurricular opportunities and would your sibling like to live in that specific city based on them?

Within the ‘out of uni’ category you might think about:

• Exit options : What are the fields in which your sibling could be employed and how long does it take the average student of that university to find a job?
• Alumni network : What percentage of alumni are employed by major companies?
• Signal : What percentage of applicants from the university get an interview in major engineering companies and related technical fields?

You will perhaps notice that all the buckets discussed pose quantifiable questions meant to provide us with data necessary to make a decision. It’s no point to ask ‘Which university has the nicest teaching staff?’ as that can be a very subjective metric.

5.3.1 Impact

Another key concept to consider when dealing with sectors other than the private one is how impactful a decision or a line of inquiry is on the overarching issue , or whether all our branches in our issue tree have a similar impact. This can often come in the form of impact on lives, such as in McKinsey’s conservation case discussed below, namely how many species can we save with our choice of habitat.

5.4 Common consulting concepts

Consultants use basic business concepts on an every day basis, as they help them articulate their frameworks to problems. However, they also use some consulting specific tools to quality check their analysis and perform in the most efficient way possible. These principles can be applied to all aspects of a consultant’s work, but for brevity we can say they mostly impact a consultant’s systematic approach and communication - two very important things that are also tested in case interviews. Therefore, it’s imperative that you not only get to know them, but learn how and when to use them as they are at the very core of good casing. They are MECE-ness, the Pareto Principle and the Pyramid principle and are explained briefly below - you should, however, go on to study them in-depth in their respective articles.

Perhaps the central pillar of all consulting work and an invaluable tool to solve cases, MECE stands for Mutually Exclusive and Collectively Exhaustive . It can refer to any and every aspect in a case but is most often used when talking about structure. We have a detailed article explaining the concept here , but the short version is that MECE-ness ensures that there is no overlap between elements of a structure (i.e. the Mutually Exclusive component) and that it covers all the drivers or areas of a problem (Collectively Exhaustive). It is a concept that can be applied to any segmentation when dividing a set into subsets that include it wholly but do not overlap.

Let’s take a simple example and then a case framework example. In simple terms, when we are asked to break down the set ‘cars’ into subsets, dividing cars into ‘red cars’ and ‘sports cars’ is neither mutually exclusive (as there are indeed red sports cars) nor exhaustive of the whole set (i.e. there are also yellow non-sports cars that are not covered by this segmentation). A MECE way to segment would be ‘cars produced before 2000’ and ‘cars produced after 2000’ as this segmentation allows for no overlap and covers all the cars in existence.

Dividing cars can be simple, but how can we ensure MECEness in a case-interview a.k.a. a business situation. While the same principles apply, a good tip to ensure that your structure is MECE is to think about all the stakeholders - i.e. those whom a specific venture involves.

Let’s consider that our client is a soda manufacturer who wants to move from a business-to-business strategy, i.e. selling to large chains of stores and supermarkets, to a business-to-consumer strategy where it sells directly to consumers. In doing so they would like to retrain part of their account managers as direct salespeople and need to know what factors to consider.

A stakeholder-driven approach would be to consider the workforce and customers and move further down the issue tree, thinking about individual issues that might affect them. In the case of the workforce, we might consider how the shift would affect their workload and whether it takes their skillset into account. As for the customers, we might wonder whether existing customers would be satisfied with this move: will the remaining B2B account managers be able to provide for the needs of all their clients and will the fact that the company is selling directly to consumers now not cannibalise their businesses? We see how by taking a stakeholder-centred approach we can ensure that every single perspective and potential issue arising from it is fully covered.

5.4.2 The Pareto Principle

Also known as the 80/20 rule, this principle is important when gauging the impact of a decision or a factor in your analysis. It simply states that in business (but not only) 80% of outcomes come from 20% of causes. What this means is you can make a few significant changes that will impact most of your business organisation, sales model, cost structure etc.

Let’s have a look at 3 quick examples to illustrate this:

• 80% of all accidents are caused by 20% of drivers
• 20% of a company’s products account for 80% of the sales
• 80% of all results in a company are driven by 20% of its employees

The 80/20 rule will be a very good guide line in real engagements as well as case interviews, as it will essentially point to the easiest and most straightforward way of doing things. Let’s say one of the questions in a case is asking you to come up with an approach to understand the appeal of a new beard trimmer. Obviously you can’t interview the whole male population so you might think about setting up a webpage and asking people to comment their thoughts. But what you would get would be a laundry list of difficult to sift through data.

Using an 80/20 approach you would segment the population based on critical factors (age groups, grooming habits etc.) and then approach a significant sample size of each (e.g. 20), analysing the data and reaching a conclusion.

5.4.3 The Pyramid Principle

This principle refers to organising your communication in a top-down , efficient manner. While this is generally applicable, the pyramid principle will most often be employed when delivering the final recommendation to your client. This means - as is implicit in the name - that you would organise your recommendation (and communication in general) as a pyramid, stating the conclusion or most important element at the top then go down the pyramid listing 3 supporting arguments and then further (ideally also 3) supporting arguments for those supporting arguments.

Let’s look at this in practice in a case interview context: your client is a German air-conditioning unit manufacturer who was looking to expand into the French market. However, after your analysis you’ve determined that the market share they were looking to capture would not be feasible. A final recommendation using the Pyramid Principle would sound something like this: ‘I recommend that we do not enter the German market for the following three reasons. Firstly, the market is too small for our ambitions of $50 million. Secondly the market is heavily concentrated, being controlled by three major players and our 5 year goal would amount to controlling 25% of the market, a share larger than that of any of the players. Thirdly, the alternative of going into the corporate market would not be feasible, as it has high barriers to entry.Then, if needed, we could delve deeper into each of our categories

6. Case examples or building blocks?

As we mentioned before, in your case interview preparation you will undoubtedly find preparation resources that claim that there are several standard types of cases and that there is a general framework that can be applied to each type of case. While there are indeed cases that are straightforward at least in appearance and seemingly invite the application of such frameworks, the reality is never that simple and cases often involve multiple or more complicated components that cannot be fitted into a simple framework.

At MCC we don’t want you to get into the habit of trying to identify which case type you’re dealing with and pull out a framework, but we do recognize that there are recurring elements in frameworks that are useful - such as the profitability of a venture (with its revenues and costs), the valuation of a business, estimating and segmenting a market and pricing a product.

We call these building blocks because they can be used to build case frameworks but are not a framework in and of themselves, and they can be shuffled around and rearranged in any way necessary to be tailored to our case. Hence, our approach is not to make you think in terms of case types but work from first principles and use these building blocks to build your own framework. Let’s take two case prompts to illustrate our point.

The first is from the Bain website, where the candidate is asked whether they think it’s a good idea for their friend to open a coffee shop in Cambridge UK (see the case here ). The answer framework provided here is a very straightforward profitability analysis framework, examining the potential revenues and potential costs of the venture:

While this is a good point to start for your case interview (especially taken together with the clarifying questions), we will notice that this approach will need more tailoring to the case - for example the quantity of coffee will be determined by the market for coffee drinkers in Cambridge, which we have to determine based on preference. We are in England so a lot of people will be drinking tea but we are in a university town so perhaps more people than average are drinking coffee as it provides a better boost when studying. All these are some much needed case-tailored hypotheses that we can make based on the initial approach.

Just by looking at this case we might be tempted to say that we can just take a profitability case and apply it without any issues. However, this generic framework is just a starting point and in reality we would need to tailor it much further in the way we had started to do in order to get to a satisfactory answer. For example, the framework for this specific case interview doesn’t cover aspects such as the customer’s expertise: does the friend have any knowledge of the coffee business, such as where to source coffee and how to prepare it? Also, we could argue there may be some legal factors to consider here, such as any approvals that they might need from the city council to run a coffee shop on site, or some specific trade licences that are not really covered in the basic profitability framework.

Let’s take a different case , however, from the McKinsey website. In this scenario, the candidate is being asked to identify some factors in order to choose where to focus the client’s conservation efforts. Immediately we can realise that this case doesn’t lend itself to any pre-packaged framework and we will need to come up with something from scratch - and take a look at McKinsey’s answer of the areas to focus on:

We notice immediately that this framework is 100% tailored to the case - of course there are elements which we encounter in other cases, such as costs and risks but again these are applied in an organic way. It’s pretty clear that while no standard framework would work in this case, the aforementioned concepts - costs and risks - and the way to approach them (a.k.a building blocks ) are fundamentally similar throughout cases (with the obvious specificities of each case).

In what follows, we’ll give a brief description of each building block starting from the Bain example discussed previously, in order to give you a general idea of what they are and their adaptability, but you should make sure to follow the link to the in-depth articles to learn all their ins and outs.

6.1 Estimates and segmentation

This building block will come into play mostly when you’re thinking about the market for a certain product (but make sure to read the full article for more details). Let’s take our Bain Cambridge coffee example. As we mentioned under the quantity bucket we need to understand what the market size for coffee in Cambridge would be - so we can make an estimation based on segmentation .

The key to a good estimation is the ability to logically break down the problem into more manageable pieces. This will generally mean segmenting a wider population to find a particular target group. We can start off with the population of Cambridge - which we estimate at 100.000. In reality the population is closer to 150.000 but that doesn’t matter - the estimation has to be reasonable and not accurate , so unless the interviewer gives you a reason to reconsider you can follow your instinct. We can divide that into people who do and don’t drink coffee. Given our arguments before, we can conclude that 80% of those, so 80.000 drink coffee. Then we can further segment into those who drink regularly - let’s say every day - and those who drink occasionally - let’s say once a week. Based on the assumptions before about the student population needing coffee to function, and with Cambridge having a high student population, we can assume that 80% of those drinking coffee are regular drinkers, so that would be 64.000 regular drinkers and 16.000 occasional drinkers. We can then decide whom we want to target what our strategy needs to be:

This type of estimation and segmentation can be applied to any case specifics - hence why it is a building block.

6.2 Profitability

We had several looks at this building block so far (see an in-depth look here ) as it will show up in most case interivew scenarios, since profit is a key element in any company’s strategy. As we have seen, the starting point to this analysis is to consider both the costs and revenues of a company, and try to determine whether revenues need to be improved or whether costs need to be lowered. In the coffee example, the revenues are dictated by the average price per coffe x the number of coffees sold , whereas costs can be split into fixed and variable .

Some examples of fixed costs would be the rent for the stores and the cost of the personnel and utilities, while the most obvious variable costs would be the coffee beans used and the takeaway containers (when needed). We may further split revenues in this case into Main revenues - i.e. the sales of coffee - and Ancillary revenues , which can be divided into Sales of food products (sales of pastries, sandwiches etc., each with the same price x quantity schema) and Revenues from events - i.e renting out the coffee shop to events and catering for the events themselves. Bear in mind that revenues will be heavily influenced by the penetration rate , i.e. the share of the market which we can capture.

6.3 Pricing

Helping a company determine how much they should charge for their goods or services is another theme that comes up frequently in cases. While it may seem less complicated than the other building blocks, we assure you it’s not - you will have to understand and consider several factors, such as the costs a company is incurring, their general strategic positioning, availability, market trends as well as the customers’ willingness to pay (or WTP in short) - so make sure to check out our in-depth guide here .

In our example, we may determine that the cost per cup (coffee beans, staff, rent) is £1. We want to be student friendly so we should consider how much students would want to pay for a coffee as well as how much are competitors are charging. Based on those factors, it would be reasonable to charge on average £2 per cup of coffee. It’s true that our competitors are charging £3 but they are targeting mostly the adult market, whose willingness to pay is higher, so their pricing model takes that into account as well as the lower volume of customers in that demographic.

6.4. Valuation

A variant of the pricing building block, a valuation problem generally asks the candidate to determine how much a client should pay for a specific company (the target of an acquisition) as well as what other factors to consider. The two most important factors (but not the only ones - for a comprehensive review see our Valuation article ) to consider are the net present value (in consulting interviews usually in perpetuity) and the synergies .

In short, the net present value of a company is how much profit it currently brings in, divided by how much that cash flow will depreciate in the future and can be represented with the equation below:

The synergies refer to what could be achieved should the companies operate as one, and can be divided into cost and revenue synergies .

Let’s expand our coffee example a bit to understand these. Imagine that our friend manages to open a chain of coffee shops in Cambridge and in the future considers acquiring a chain of take-out restaurants. The most straightforward example of revenue synergies would be cross-selling, in this case selling coffee in the restaurants as well as in the dedicated stores, and thus getting an immediate boost in market share by using the existing customers of the restaurant chain. A cost synergy would be merging the delivery services of the two businesses to deliver both food and coffee, thus avoiding redundancies and reducing costs associated with twice the number of drivers and vehicles.

6.5. Competitive interaction

This component of cases deals with situations where the market in which a company is operating changes and the company must decide what to do. These changes often have to do with a new player entering the market (again for more details make sure to dive into the Competitive Interaction article ).

Let’s assume that our Cambridge coffee shop has now become a chain and has flagged up to other competitors that Cambridge is a blooming market for coffee. As such, Starbucks has decided to open a few stores in Cambridge themselves, to test this market. The question which might be posed to a candidate is what should our coffee chain do. One way (and a MECE one) to approach the problem is to decide between doing something and doing nothing . We might consider merging with another coffee chain and pooling our resources or playing to our strengths and repositioning ourselves as ‘your student-friendly, shop around the corner’. Just as easily we may just wait the situation out and see whether indeed Starbucks is cutting into our market share - after all, the advantages of our product and services might speak for themselves and Starbucks might end up tanking. Both of these are viable options if argued right and depending on the further specifics of the case.

6.6. Special cases

Most cases deal with private sectors, where the overarching objective entails profit in some form. However, as hinted before, there are cases which deal with other sectors where there are other KPIs in place . The former will usually contain one or several of these building blocks whereas the latter will very likely have neither. This latter category is arguably the one that will stretch your analytical and organisational skills to the limit, since there will be very little familiarity that you can fall back on (McKinsey famously employs such cases in their interview process).

So how do we tackle the structure for such cases? The short answer would be starting from first principles and using the problem driven structure outlined above, but let’s look at a quick example in the form of a McKinsey case :

The first question addressed to the candidate is the following:

This is in fact asking us to build a structure for the case. So what should we have in mind here? Most importantly, we should start with a structure that is MECE and we should remember to do that by considering all the stakeholders . They are on the one hand the government and affiliated institutions and on the other the population. We might then consider which issues might arise for each shareholder and what the benefits for them would be, as well as the risks. This approach is illustrated in the answer McKinsey provides as well:

More than anything, this type of case shows us how important it is to practise and build different types of structures, and think about MECE ways of segmenting the problem.

7. How Do I prepare for case interviews

In consulting fashion, the overall preparation can be structured into theoretical preparation and practical preparation , with each category then being subdivided into individual prep and prep with a partner .

As a general rule, the level and intensity of the preparation will differ based on your background - naturally if you have a business background (and have been part of a consulting club or something similar) your preparation will be less intensive than if you’re starting from scratch. The way we suggest you go about it is to start with theoretical preparation , which means learning about case interviews, business and basic consulting concepts (you can do this using free resources - such as the ones we provide - or if you want a more through preparation you can consider joining our Case Academy as well).

You can then move on to the practical preparation which should start with doing solo cases and focusing on areas of improvement, and then move on to preparation with a partner , which should be another candidate or - ideally - an ex-consultant.

Let’s go into more details with respect to each type of preparation.

7.1. Solo practice

The two most important areas of focus in sole preparation are:

• Mental math

As we mentioned briefly, the best use of your time is to focus on solving cases. You can start with cases listed on MBB sites since they are clearly stated and have worked solutions as well (e.g. Bain is a good place to start) and then move to more complex cases (our Case Library also offers a range of cases of different complexities). To build your confidence, start out on easier case questions, work through with the solutions, and don't worry about time. As you get better, you can move on to more difficult cases and try to get through them more quickly. You should practice around eight case studies on your own to build your confidence.

Another important area of practice is your mental mathematics as this skill will considerably increase your confidence and is neglected by many applicants - much to their immediate regret in the case interview. Find our mental math tool here or in our course, and practice at least ten minutes per day, from day one until the day before the interview.

7.2. Preparation with a partner

There are aspects of a case interview - such as asking clarifying questions - which you cannot do alone and this is why, after you feel comfortable, you should move on to practice with another person. There are two options here:

• Practicing with a peer
• Practicing with an ex-consultant

In theory they can be complementary - especially if you’re peer is also preparing for consulting interviews - and each have advantages and disadvantages. A peer is likely to practice with you for free for longer, however you may end up reinforcing some bad habits or unable to get actionable feedback. A consultant will be able to provide you the latter but having their help for the same number of hours as a peer will come at a higher cost. Let’s look at each option in more detail.

7.2.1. Peer preparation

Once you have worked through eight cases solo, you should be ready to simulate the case interview more closely and start working with another person.

Here, many candidates turn to peer practice - that is, doing mock case interviews with friends, classmates or others also applying to consulting. If you’re in university, and especially in business school, there will very likely be a consulting club for you to join and do lots of case practice with. If you don’t have anyone to practice, though, or if you just want to get a bit more volume in with others, our free meeting board lets you find fellow applicants from around the world with whom to practice. We recommend practicing around 10 to 15 ‘live’ cases to really get to a point where you feel comfortable.

7.2.2. Preparation with a consultant

You can do a lot practising by yourself and with peers. However, nothing will bring up your skills so quickly and profoundly as working with a real consultant.

Perhaps think about it like boxing. You can practice drills and work on punch bags all you want, but at some point you need to get into the ring and do some actual sparring if you ever want to be ready to fight.

Practicing with an ex consultant is essentialy a simulation of a case interview. Of course, it isn’t possible to secure the time of experienced top-tier consultants for free. However, when considering whether you should invest to boost your chances of success, it is worth considering the difference in your salary over even just a few years between getting into a top-tier firm versus a second-tier one. In the light of thousands in increased annual earnings (easily accumulating into millions over multiple years), it becomes clear that getting expert interview help really is one of the best investments you can make in your own future.

Should you decide to make this step, MyConsultingCoach can help, offering bespoke mentoring programmes , where you are paired with a 5+ year experienced, ex-MBB mentor of your choosing, who will then oversee your whole case interview preparation from start to finish - giving you your best possible chance of landing a job!

7.3. Practice for online interviews

Standard preparation for interview case studies will carry directly over to online cases.

However, if you want to do some more specific prep, you can work through cases solo to a timer and using a calculator and/or Excel (online cases generally allow calculators and second computers to help you, whilst these are banned in live case interviews).

Older PST-style questions also make great prep, but a particularly good simulation is the self-assessment tests included in our Case Academy course . These multiple choice business questions conducted with a strict time limit are great preparation for the current crop of online cases.

7.4. Fit interviews

As we’ve noted, even something billed as a case interview is very likely to contain a fit interview as a subset.

We have an article on fit interviews and also include a full set of lessons on how to answer fit questions properly as a subset of our comprehensive Case Academy course .

Here though, the important thing to convey is that you take preparing for fit questions every bit as seriously as you do case prep.

Since they sound the same as you might encounter when interviewing for other industries, the temptation is to regard these as “just normal interview questions”.

However, consulting firms take your answers to these questions a good deal more seriously than elsewhere.

This isn’t just for fluffy “corporate culture” reasons. The long hours and close teamwork, as well as the client-facing nature of management consulting, mean that your personality and ability to get on with others is going to be a big part of making you a tolerable and effective co-worker.

If you know you’ll have to spend 14+ hour working days with someone you hire and that your annual bonus depends on them not alienating clients, you better believe you’ll pay attention to their character in interview.

There are also hard-nosed financial reasons for the likes of McKinsey, Bain and BCG to drill down so hard on your answers.

In particular, top consultancies have huge issues with staff retention. The average management consultant only stays with these firms for around two years before they have moved on to a new industry.

In some cases, consultants bail out because they can’t keep up with the arduous consulting lifestyle of long hours and endless travel. In many instances, though, departing consultants are lured away by exit opportunities - such as the well trodden paths towards internal strategy roles, private equity or becoming a start-up founder.

Indeed, many individuals will intentionally use a two year stint in consulting as something like an MBA they are getting paid for - giving them accelerated exposure to the business world and letting them pivot into something new.

Consulting firms want to get a decent return on investment for training new recruits. Thus, they want hires who not only intend to stick with consulting longer-term, but also have a temperament that makes this feasible and an overall career trajectory where it just makes sense for them to stay put.

This should hammer home the point that, if you want to get an offer, you need to be fully prepared to answer fit questions - and to do so excellently - any time you have a case interview.

8. Interview day - what to expect, with tips

Of course, all this theory is well and good, but a lot of readers might be concerned about what exactly to expect in real life . It’s perfectly reasonable to want to get as clear a picture as possible here - we all want to know what we are going up against when we face a new challenge!

Indeed, it is important to think about your interview in more holistic terms, rather than just focusing on small aspects of analysis. Getting everything exactly correct is less important than the overall approach you take to reasoning and how you communicate - and candidates often lose sight of this fact.

In this section, then, we’ll run through the case interview experience from start to finish, directing you to resources with more details where appropriate. As a supplement to this, the following video from Bain is excellent. It portrays an abridged version of a case interview, but is very useful as a guide to what to expect - not just from Bain, but from McKinsey, BCG and any other high-level consulting firm.

8.1. Getting started

Though you might be shown through to the office by a staff member, usually your interviewer will come and collect you from a waiting area. Either way, when you first encounter them, you should greet your interviewer with a warm smile and a handshake (unless they do not offer their hand). Be confident without verging into arrogance. You will be asked to take a seat in the interviewer’s office, where the case interview can then begin.

8.1.1. First impressions

In reality, your assessment begins before you even sit down at your interviewer’s desk. Whether at a conscious level or not, the impression you make within the first few seconds of meeting your interviewer is likely to significantly inform the final hiring decision (again, whether consciously or not).

Your presentation and how you hold yourself and behave are all important . If this seems strange, consider that, if hired, you will be personally responsible for many clients’ impressions of the firm. These things are part of the job! Much of material on the fit interview is useful here, whilst we also cover first impressions and presentation generally in our article on what to wear to interview .

As we have noted above, your interview might start with a fit segment - that is, with the interviewer asking questions about your experiences, your soft skills, and motivation to want to join consulting generally and that firm in particular. In short, the kinds of things a case study can’t tell them about you. We have a fit interview article and course to get you up to speed here.

8.1.2. Down to business

Following an initial conversation, your interviewer will introduce your case study , providing a prompt for the question you have to answer. You will have a pen and paper in front of you and should (neatly) note down the salient pieces of information (keep this up throughout the interview).

It is crucial here that you don’t delve into analysis or calculations straight away . Case prompts can be tricky and easy to misunderstand, especially when you are under pressure. Rather, ask any questions you need to fully understand the case question and then validate that understanding with the interviewer before you kick off any analysis. Better to eliminate mistakes now than experience that sinking feeling of realising you have gotten the whole thing wrong halfway through your case!

This process is covered in our article on identifying the problem and in greater detail in our Case Academy lesson on that subject.

8.1.3. Analysis

Once you understand the problem, you should take a few seconds to set your thoughts in order and draw up an initial structure for how you want to proceed. You might benefit from utilising one or more of our building blocks here to make a strong start. Present this to your interviewer and get their approval before you get into the nuts and bolts of analysis.

We cover the mechanics of how to structure your problem and lead the analysis in our articles here and here and more thoroughly in the MCC Case Academy . What it is important to convey here, though, is that your case interview is supposed to be a conversation rather than a written exam . Your interviewer takes a role closer to a co-worker than an invigilator and you should be conversing with them throughout.

Indeed, how you communicate with your interviewer and explain your rationale is a crucial element of how you will be assessed. Case questions in general, are not posed to see if you can produce the correct answer, but rather to see how you think . Your interviewer wants to see you approach the case in a structured, rational fashion. The only way they are going to know your thought processes, though, is if you tell them!

To demonstrate this point, here is another excellent video from Bain, where candidates are compared.

Note that multiple different answers to each question are considered acceptable and that Bain is primarily concerned with the thought processes of the candidate’s exhibit .

Another reason why communication is absolutely essential to case interview success is the simple reason that you will not have all the facts you need to complete your analysis at the outset. Rather, you will usually have to ask the interviewer for additional data throughout the case to allow you to proceed .

NB: Don't be let down by your math!

Your ability to quickly and accurately interpret these charts and other figures under pressure is one of the skills that is being assessed. You will also need to make any calculations with the same speed and accuracy (without a calculator!). As such, be sure that you are up to speed on your consulting math .

8.1.4. Recommendation

Finally, you will be asked to present a recommendation. This should be delivered in a brief, top-down "elevator pitch" format , as if you are speaking to a time-pressured CEO. Again here, how you communicate will be just as important as the details of what you say, and you should aim to speak clearly and with confidence.

For more detail on how to give the perfect recommendation, take a look at our articles on the Pyramid Principle and providing recommendations , as well the relevant lesson within MCC Academy .

8.1.5. Wrapping up

After your case is complete, there might be a few more fit questions - including a chance for you to ask some questions of the interviewer . This is your opportunity to make a good parting impression.

We deal with the details in our fit interview resources. However, it is always worth bearing in mind just how many candidates your interviewers are going to see giving similar answers to the same questions in the same office. A pretty obvious pre-requisite to being considered for a job is that your interviewer remembers you in the first place. Whilst you shouldn't do something stupid just to be noticed, asking interesting parting questions is a good way to be remembered.

Now, with the interview wrapped up, it’s time to shake hands, thank the interviewer for their time and leave the room .

You might have other case interviews or tests that day or you might be heading home. Either way, if know that you did all you could to prepare, you can leave content in the knowledge that you have the best possible chance of receiving an email with a job offer. This is our mission at MCC - to provide all the resources you need to realise your full potential and land your dream consulting job!

8.2. Remote and one-way interview tips

Zoom case interviews and “one-way” automated fit interviews are becoming more common as selection processes are increasingly remote, with these new formats being accompanied by their own unique challenges.

Obviously you won’t have to worry about lobbies and shaking hands for a video interview. However, a lot remains the same. You still need to do the same prep in terms of getting good at case cracking and expressing your fit answers. The specific considerations around remote case interviews are, in effect, around making sure you come across as effectively as you would in person.

8.2.1. Connection

It sounds trivial, but a successful video case interview of any kind presupposes a functioning computer with a stable and sufficient internet connection.

Absolutely don’t forget to have your laptop plugged in, as your battery will definitely let you down mid-interview. Similarly, make sure any housemates or family know not to use the microwave, vacuum cleaner or anything else that makes wifi cut out (or makes a lot of noise, obviously)

If you have to connect on a platform you don’t use much (for example, if it’s on Teams and you’re used to Zoom), make sure you have the up to date version of the app in advance, rather than having to wait for an obligatory download and end up late to join. Whilst you’re at it, make sure you’re familiar with the controls etc. At the risk of being made fun of, don’t be afraid to have a practice call with a friend.

8.2.2. Dress

You might get guidance on a slightly more relaxed dress code for a Zoom interview. However, if in doubt, dress as you would for the real thing (see our article here ).

Either way, always remember that presentation is part of what you are being assessed on - the firm needs to know you can be presentable for clients. Taking this stuff seriously also shows respect for your interviewer and their time in interviewing you.

8.2.3. Lighting

An aspect of presentation that you have to devote some thought to for a Zoom case interview is your lighting.

Hopefully, you long ago nailed a lighting set-up during the Covid lockdowns. However, make sure to check your lighting in advance with your webcam - bearing in mind what time if day your case interview actually is. If your case interview is late afternoon, don’t just check in the morning. Make sure you aren’t going to be blinded from light coming in a window behind your screen, or that you end up with the weird shadow stripes from blinds all over your face.

Natural light is always best, but if there won’t be much of that during your interview, you’ll likely want to experiment with moving some lamps around.

8.2.4. Clarity

The actual stories you tell in an automated “one-way” fit interview will be the same as for a live equivalent. If anything, things should be easier, as you can rattle off a practised monologue without an interviewer interrupting you to ask for clarifications.

You can probably also assume that the algorithm assessing your performance is sufficiently capable that it will be observing you at much the same level as a human interviewer. However, it is probably still worth speaking as clearly as possible with these kinds of interviews and paying extra attention to your lighting to ensure that your face is clearly visible.

No doubt the AIs scoring these interviews are improving all the time, but you still want to make their job as easy as possible. Just think about the same things as you would with a live Zoom case interview, but more so.

9. How we can help

There are lots of great free resources on this site to get you started with preparation, from all our articles on case solving and consulting skills to our free case library and peer practice meeting board .

To step your preparation up a notch, though, our Case Academy course will give you everything you need to know to solve the most complex of cases - whether those are in live case interviews, with chatbots, written tests or any other format.

Whatever kind of case you end up facing, nothing will bring up your skillset faster than the kind of acute, actionable feedback you can get from a mock case interview a real, MBB consultant. Whilst it's possible to get by without this kind of coaching, it does tend to be the biggest single difference maker for successful candidates.

You can find out more on our coaching page:

Explore Coaching

Of course, for those looking for a truly comprehensive programme, with a 5+ year experienced MBB consultant overseeing their entire prep personally, from networking and applications right through to your offer, we have our mentoring programmes.

You can read more here:

Comprehensive Mentoring

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What the Case Study Method Really Teaches

by Nitin Nohria

Summary .   

It’s been 100 years since Harvard Business School began using the case study method. Beyond teaching specific subject matter, the case study method excels in instilling meta-skills in students. This article explains the importance of seven such skills: preparation, discernment, bias recognition, judgement, collaboration, curiosity, and self-confidence.

During my decade as dean of Harvard Business School, I spent hundreds of hours talking with our alumni. To enliven these conversations, I relied on a favorite question: “What was the most important thing you learned from your time in our MBA program?”

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The Ultimate Guide to Qualitative Research - Part 1: The Basics

• Introduction and overview
• What is qualitative research?
• What is qualitative data?
• Examples of qualitative data
• Qualitative vs. quantitative research
• Mixed methods
• Qualitative research preparation
• Theoretical perspective
• Theoretical framework
• Literature reviews

Research question

• Conceptual framework
• Conceptual vs. theoretical framework

Data collection

• Qualitative research methods
• Focus groups
• Observational research

What is a case study?

Applications for case study research, what is a good case study, process of case study design, benefits and limitations of case studies.

• Ethnographical research
• Ethical considerations
• Confidentiality and privacy
• Power dynamics
• Reflexivity

Case studies

Case studies are essential to qualitative research , offering a lens through which researchers can investigate complex phenomena within their real-life contexts. This chapter explores the concept, purpose, applications, examples, and types of case studies and provides guidance on how to conduct case study research effectively.

Whereas quantitative methods look at phenomena at scale, case study research looks at a concept or phenomenon in considerable detail. While analyzing a single case can help understand one perspective regarding the object of research inquiry, analyzing multiple cases can help obtain a more holistic sense of the topic or issue. Let's provide a basic definition of a case study, then explore its characteristics and role in the qualitative research process.

Definition of a case study

A case study in qualitative research is a strategy of inquiry that involves an in-depth investigation of a phenomenon within its real-world context. It provides researchers with the opportunity to acquire an in-depth understanding of intricate details that might not be as apparent or accessible through other methods of research. The specific case or cases being studied can be a single person, group, or organization – demarcating what constitutes a relevant case worth studying depends on the researcher and their research question .

Among qualitative research methods , a case study relies on multiple sources of evidence, such as documents, artifacts, interviews , or observations , to present a complete and nuanced understanding of the phenomenon under investigation. The objective is to illuminate the readers' understanding of the phenomenon beyond its abstract statistical or theoretical explanations.

Characteristics of case studies

Case studies typically possess a number of distinct characteristics that set them apart from other research methods. These characteristics include a focus on holistic description and explanation, flexibility in the design and data collection methods, reliance on multiple sources of evidence, and emphasis on the context in which the phenomenon occurs.

Furthermore, case studies can often involve a longitudinal examination of the case, meaning they study the case over a period of time. These characteristics allow case studies to yield comprehensive, in-depth, and richly contextualized insights about the phenomenon of interest.

The role of case studies in research

Case studies hold a unique position in the broader landscape of research methods aimed at theory development. They are instrumental when the primary research interest is to gain an intensive, detailed understanding of a phenomenon in its real-life context.

In addition, case studies can serve different purposes within research - they can be used for exploratory, descriptive, or explanatory purposes, depending on the research question and objectives. This flexibility and depth make case studies a valuable tool in the toolkit of qualitative researchers.

Remember, a well-conducted case study can offer a rich, insightful contribution to both academic and practical knowledge through theory development or theory verification, thus enhancing our understanding of complex phenomena in their real-world contexts.

What is the purpose of a case study?

Case study research aims for a more comprehensive understanding of phenomena, requiring various research methods to gather information for qualitative analysis . Ultimately, a case study can allow the researcher to gain insight into a particular object of inquiry and develop a theoretical framework relevant to the research inquiry.

Why use case studies in qualitative research?

Using case studies as a research strategy depends mainly on the nature of the research question and the researcher's access to the data.

Conducting case study research provides a level of detail and contextual richness that other research methods might not offer. They are beneficial when there's a need to understand complex social phenomena within their natural contexts.

The explanatory, exploratory, and descriptive roles of case studies

Case studies can take on various roles depending on the research objectives. They can be exploratory when the research aims to discover new phenomena or define new research questions; they are descriptive when the objective is to depict a phenomenon within its context in a detailed manner; and they can be explanatory if the goal is to understand specific relationships within the studied context. Thus, the versatility of case studies allows researchers to approach their topic from different angles, offering multiple ways to uncover and interpret the data .

The impact of case studies on knowledge development

Case studies play a significant role in knowledge development across various disciplines. Analysis of cases provides an avenue for researchers to explore phenomena within their context based on the collected data.

This can result in the production of rich, practical insights that can be instrumental in both theory-building and practice. Case studies allow researchers to delve into the intricacies and complexities of real-life situations, uncovering insights that might otherwise remain hidden.

Types of case studies

In qualitative research , a case study is not a one-size-fits-all approach. Depending on the nature of the research question and the specific objectives of the study, researchers might choose to use different types of case studies. These types differ in their focus, methodology, and the level of detail they provide about the phenomenon under investigation.

Understanding these types is crucial for selecting the most appropriate approach for your research project and effectively achieving your research goals. Let's briefly look at the main types of case studies.

Exploratory case studies

Exploratory case studies are typically conducted to develop a theory or framework around an understudied phenomenon. They can also serve as a precursor to a larger-scale research project. Exploratory case studies are useful when a researcher wants to identify the key issues or questions which can spur more extensive study or be used to develop propositions for further research. These case studies are characterized by flexibility, allowing researchers to explore various aspects of a phenomenon as they emerge, which can also form the foundation for subsequent studies.

Descriptive case studies

Descriptive case studies aim to provide a complete and accurate representation of a phenomenon or event within its context. These case studies are often based on an established theoretical framework, which guides how data is collected and analyzed. The researcher is concerned with describing the phenomenon in detail, as it occurs naturally, without trying to influence or manipulate it.

Explanatory case studies

Explanatory case studies are focused on explanation - they seek to clarify how or why certain phenomena occur. Often used in complex, real-life situations, they can be particularly valuable in clarifying causal relationships among concepts and understanding the interplay between different factors within a specific context.

Intrinsic, instrumental, and collective case studies

These three categories of case studies focus on the nature and purpose of the study. An intrinsic case study is conducted when a researcher has an inherent interest in the case itself. Instrumental case studies are employed when the case is used to provide insight into a particular issue or phenomenon. A collective case study, on the other hand, involves studying multiple cases simultaneously to investigate some general phenomena.

Each type of case study serves a different purpose and has its own strengths and challenges. The selection of the type should be guided by the research question and objectives, as well as the context and constraints of the research.

The flexibility, depth, and contextual richness offered by case studies make this approach an excellent research method for various fields of study. They enable researchers to investigate real-world phenomena within their specific contexts, capturing nuances that other research methods might miss. Across numerous fields, case studies provide valuable insights into complex issues.

Critical information systems research

Case studies provide a detailed understanding of the role and impact of information systems in different contexts. They offer a platform to explore how information systems are designed, implemented, and used and how they interact with various social, economic, and political factors. Case studies in this field often focus on examining the intricate relationship between technology, organizational processes, and user behavior, helping to uncover insights that can inform better system design and implementation.

Health research

Health research is another field where case studies are highly valuable. They offer a way to explore patient experiences, healthcare delivery processes, and the impact of various interventions in a real-world context.

Case studies can provide a deep understanding of a patient's journey, giving insights into the intricacies of disease progression, treatment effects, and the psychosocial aspects of health and illness.

Asthma research studies

Specifically within medical research, studies on asthma often employ case studies to explore the individual and environmental factors that influence asthma development, management, and outcomes. A case study can provide rich, detailed data about individual patients' experiences, from the triggers and symptoms they experience to the effectiveness of various management strategies. This can be crucial for developing patient-centered asthma care approaches.

Other fields

Apart from the fields mentioned, case studies are also extensively used in business and management research, education research, and political sciences, among many others. They provide an opportunity to delve into the intricacies of real-world situations, allowing for a comprehensive understanding of various phenomena.

Case studies, with their depth and contextual focus, offer unique insights across these varied fields. They allow researchers to illuminate the complexities of real-life situations, contributing to both theory and practice.

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Understanding the key elements of case study design is crucial for conducting rigorous and impactful case study research. A well-structured design guides the researcher through the process, ensuring that the study is methodologically sound and its findings are reliable and valid. The main elements of case study design include the research question , propositions, units of analysis, and the logic linking the data to the propositions.

The research question is the foundation of any research study. A good research question guides the direction of the study and informs the selection of the case, the methods of collecting data, and the analysis techniques. A well-formulated research question in case study research is typically clear, focused, and complex enough to merit further detailed examination of the relevant case(s).

Propositions

Propositions, though not necessary in every case study, provide a direction by stating what we might expect to find in the data collected. They guide how data is collected and analyzed by helping researchers focus on specific aspects of the case. They are particularly important in explanatory case studies, which seek to understand the relationships among concepts within the studied phenomenon.

Units of analysis

The unit of analysis refers to the case, or the main entity or entities that are being analyzed in the study. In case study research, the unit of analysis can be an individual, a group, an organization, a decision, an event, or even a time period. It's crucial to clearly define the unit of analysis, as it shapes the qualitative data analysis process by allowing the researcher to analyze a particular case and synthesize analysis across multiple case studies to draw conclusions.

Argumentation

This refers to the inferential model that allows researchers to draw conclusions from the data. The researcher needs to ensure that there is a clear link between the data, the propositions (if any), and the conclusions drawn. This argumentation is what enables the researcher to make valid and credible inferences about the phenomenon under study.

Understanding and carefully considering these elements in the design phase of a case study can significantly enhance the quality of the research. It can help ensure that the study is methodologically sound and its findings contribute meaningful insights about the case.

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Conducting a case study involves several steps, from defining the research question and selecting the case to collecting and analyzing data . This section outlines these key stages, providing a practical guide on how to conduct case study research.

Defining the research question

The first step in case study research is defining a clear, focused research question. This question should guide the entire research process, from case selection to analysis. It's crucial to ensure that the research question is suitable for a case study approach. Typically, such questions are exploratory or descriptive in nature and focus on understanding a phenomenon within its real-life context.

Selecting and defining the case

The selection of the case should be based on the research question and the objectives of the study. It involves choosing a unique example or a set of examples that provide rich, in-depth data about the phenomenon under investigation. After selecting the case, it's crucial to define it clearly, setting the boundaries of the case, including the time period and the specific context.

Previous research can help guide the case study design. When considering a case study, an example of a case could be taken from previous case study research and used to define cases in a new research inquiry. Considering recently published examples can help understand how to select and define cases effectively.

Developing a detailed case study protocol

A case study protocol outlines the procedures and general rules to be followed during the case study. This includes the data collection methods to be used, the sources of data, and the procedures for analysis. Having a detailed case study protocol ensures consistency and reliability in the study.

The protocol should also consider how to work with the people involved in the research context to grant the research team access to collecting data. As mentioned in previous sections of this guide, establishing rapport is an essential component of qualitative research as it shapes the overall potential for collecting and analyzing data.

Collecting data

Gathering data in case study research often involves multiple sources of evidence, including documents, archival records, interviews, observations, and physical artifacts. This allows for a comprehensive understanding of the case. The process for gathering data should be systematic and carefully documented to ensure the reliability and validity of the study.

Analyzing and interpreting data

The next step is analyzing the data. This involves organizing the data , categorizing it into themes or patterns , and interpreting these patterns to answer the research question. The analysis might also involve comparing the findings with prior research or theoretical propositions.

Writing the case study report

The final step is writing the case study report . This should provide a detailed description of the case, the data, the analysis process, and the findings. The report should be clear, organized, and carefully written to ensure that the reader can understand the case and the conclusions drawn from it.

Each of these steps is crucial in ensuring that the case study research is rigorous, reliable, and provides valuable insights about the case.

The type, depth, and quality of data in your study can significantly influence the validity and utility of the study. In case study research, data is usually collected from multiple sources to provide a comprehensive and nuanced understanding of the case. This section will outline the various methods of collecting data used in case study research and discuss considerations for ensuring the quality of the data.

Interviews are a common method of gathering data in case study research. They can provide rich, in-depth data about the perspectives, experiences, and interpretations of the individuals involved in the case. Interviews can be structured , semi-structured , or unstructured , depending on the research question and the degree of flexibility needed.

Observations

Observations involve the researcher observing the case in its natural setting, providing first-hand information about the case and its context. Observations can provide data that might not be revealed in interviews or documents, such as non-verbal cues or contextual information.

Documents and artifacts

Documents and archival records provide a valuable source of data in case study research. They can include reports, letters, memos, meeting minutes, email correspondence, and various public and private documents related to the case.

These records can provide historical context, corroborate evidence from other sources, and offer insights into the case that might not be apparent from interviews or observations.

Physical artifacts refer to any physical evidence related to the case, such as tools, products, or physical environments. These artifacts can provide tangible insights into the case, complementing the data gathered from other sources.

Ensuring the quality of data collection

Determining the quality of data in case study research requires careful planning and execution. It's crucial to ensure that the data is reliable, accurate, and relevant to the research question. This involves selecting appropriate methods of collecting data, properly training interviewers or observers, and systematically recording and storing the data. It also includes considering ethical issues related to collecting and handling data, such as obtaining informed consent and ensuring the privacy and confidentiality of the participants.

Data analysis

Analyzing case study research involves making sense of the rich, detailed data to answer the research question. This process can be challenging due to the volume and complexity of case study data. However, a systematic and rigorous approach to analysis can ensure that the findings are credible and meaningful. This section outlines the main steps and considerations in analyzing data in case study research.

Organizing the data

The first step in the analysis is organizing the data. This involves sorting the data into manageable sections, often according to the data source or the theme. This step can also involve transcribing interviews, digitizing physical artifacts, or organizing observational data.

Categorizing and coding the data

Once the data is organized, the next step is to categorize or code the data. This involves identifying common themes, patterns, or concepts in the data and assigning codes to relevant data segments. Coding can be done manually or with the help of software tools, and in either case, qualitative analysis software can greatly facilitate the entire coding process. Coding helps to reduce the data to a set of themes or categories that can be more easily analyzed.

Identifying patterns and themes

After coding the data, the researcher looks for patterns or themes in the coded data. This involves comparing and contrasting the codes and looking for relationships or patterns among them. The identified patterns and themes should help answer the research question.

Interpreting the data

Once patterns and themes have been identified, the next step is to interpret these findings. This involves explaining what the patterns or themes mean in the context of the research question and the case. This interpretation should be grounded in the data, but it can also involve drawing on theoretical concepts or prior research.

Verification of the data

The last step in the analysis is verification. This involves checking the accuracy and consistency of the analysis process and confirming that the findings are supported by the data. This can involve re-checking the original data, checking the consistency of codes, or seeking feedback from research participants or peers.

Like any research method , case study research has its strengths and limitations. Researchers must be aware of these, as they can influence the design, conduct, and interpretation of the study.

Understanding the strengths and limitations of case study research can also guide researchers in deciding whether this approach is suitable for their research question . This section outlines some of the key strengths and limitations of case study research.

Benefits include the following:

• Rich, detailed data: One of the main strengths of case study research is that it can generate rich, detailed data about the case. This can provide a deep understanding of the case and its context, which can be valuable in exploring complex phenomena.
• Flexibility: Case study research is flexible in terms of design , data collection , and analysis . A sufficient degree of flexibility allows the researcher to adapt the study according to the case and the emerging findings.
• Real-world context: Case study research involves studying the case in its real-world context, which can provide valuable insights into the interplay between the case and its context.
• Multiple sources of evidence: Case study research often involves collecting data from multiple sources , which can enhance the robustness and validity of the findings.

On the other hand, researchers should consider the following limitations:

• Generalizability: A common criticism of case study research is that its findings might not be generalizable to other cases due to the specificity and uniqueness of each case.
• Time and resource intensive: Case study research can be time and resource intensive due to the depth of the investigation and the amount of collected data.
• Complexity of analysis: The rich, detailed data generated in case study research can make analyzing the data challenging.
• Subjectivity: Given the nature of case study research, there may be a higher degree of subjectivity in interpreting the data , so researchers need to reflect on this and transparently convey to audiences how the research was conducted.

Being aware of these strengths and limitations can help researchers design and conduct case study research effectively and interpret and report the findings appropriately.

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Hacking the Case Interview

Looking for a case interview cheat sheet or study guide to help you prepare for your upcoming consulting interviews?

Download our Case Interview Cheat Sheet and Study Guide , which covers all of the most important things you need to know. If you are looking to read the case interview cheat sheet in plain text, we’ve included all of the text below.

This case interview cheat sheet covers:  

What is a case interview?

What do case interviews assess?

What is the structure of a case interview?

What are the common types of cases?

What formulas do you need to know for case interviews?

What numbers do you need to know for case interviews?

What are some case interview tips?

If you’re looking for a step-by-step shortcut to learn case interviews quickly, enroll in our case interview course . These insider strategies from a former Bain interviewer helped 30,000+ land consulting offers while saving hundreds of hours of prep time.

A case interview is a 30- to 45-minute exercise that places you in a hypothetical business situation in which you and the interviewer work together to develop a recommendation or answer to a business problem.

• How can Walmart increase its profitability?
• How can Nike increase customer retention?
• How should Apple price its new smartphone?

A case interview assesses five criteria:

1.   Logical, structured thinking : Can you structure complex problems and ideas in a clear and organized way?

2.  Analytical problem solving: Can you analyze and interpret data to draw the right conclusions?

3.  Business acumen : Do you have a strong understanding of business fundamentals and good business judgment?

4.  Communication skills : Can you communicate clearly, concisely, and articulately?

5.  Personality and cultural fit : Are you a good fit for the work culture of the firm you are interviewing with?

All case interviews follow seven major steps:

1.  Understand the case background : Take notes while the interviewer reads you the case information. Pay particularly close attention to the context, company, and objective.

2.  Ask  clarifying questions : If necessary, ask 1 – 3 questions to clarify the objective of the case, understand the company better, or understand an unfamiliar term.

3.  Structure a framework : Structure a framework to break down the complex business problem into simpler, smaller components. A framework is a tool that organizes different ideas into major categories. Present your framework to the interviewer. Make sure that your framework is MECE .

M utually E xclusive: None of the parts of your framework overlap with each other

C ollectively E xhaustive: All of the parts of the framework account for everything you need to know to solve the case with no major areas missing.

4.  Start the case : How the case will start depends on whether the case is an interviewer-led case or a candidate-led case .

Interviewer-led case : The interviewer will be steering and controlling the direction of the case. They will explicitly point you to which questions to answer.

Candidate-led case : You will be driving the direction of the case. You will propose what area of your framework to start in, what questions you want to answer, what analyses you want to do, and what the next step of the case is.

5.  Solve quantitative problems : There are three major types of quantitative problems you could be asked in case interviews.

Market sizing or estimation questions : You will be asked to calculate the size of a particular market or estimate a particular figure. You may need to make your own assumptions on what number to use or the interviewer may provide you with the data.

Profitability or breakeven questions : You will be asked to calculate the expected profitability of a company or investment decision. You could also be asked to calculate the conditions necessary for a company to break even .

Charts and graphs questions : You will be asked to interpret data from various charts or graphs . These can include bar charts, pie charts, line graphs, scatterplots, bubble charts, and waterfall charts.

6.  Answer qualitative questions : There are two major types of qualitative questions you could be asked in case interviews.

Brainstorming questions : You will be asked to brainstorm a list of ideas for a particular problem or question.

Business judgment questions : You will be asked for your opinion on a business issue or a strategic decision.

7. Deliver a recommendation : Present your recommendation and provide the major reasons that support it. Then, propose potential next steps that you would take if you had more time.

Profitability case : A company is experiencing a decline in profits or profitability and is trying to identify what is causing the decline and what they should do about it.

How to solve:  

• Identify the driver behind the decline in profitability, whether it is from a decline in revenue, increase in costs, or both
• Understand what is causing this by looking at customer needs, competitor moves, and market trends
• Identify ways to improve profitability

Growth strategy case : A company is trying to decide how to best grow its business.

• Determine whether the company is looking to grow organically or inorganically
• For organic growth, consider growth through existing revenue sources and new revenue sources
• For inorganic growth, consider potential acquisitions and partnerships

Market entry case : A company is trying to decide whether they should enter a particular new market.

• Determine whether the market is attractive
• Assess the competitive landscape
• Determine if the company has the capabilities to enter
• Estimate the expected profitability from entering

Merger & acquisition case : A company is trying to decide whether or not they should acquire or merge with a particular company.

• Determine whether the company is attractive
• Assess potential synergies and risks
• Estimate the financial implications

New product case : A company is trying to decide whether or not they should develop and launch a particular new product.

How to solve:

• Determine whether the market that the product targets is attractive
• Assess whether the product meets customer needs and is superior to competitor products
• Determine whether the company has the capabilities to successfully develop and launch the product
• Estimate the expected profitability from launching the product

Pricing case : A company is trying to decide the best way to price a particular product or service.

• Determine the cost to produce the product. This is your minimum price.
• Estimate the customer’s maximum willingness to pay by quantifying the value the product provides. This is your maximum price.
• Investigate the price that competitors are setting for similar products. This will help you determine the optimal price between your minimum and maximum price.

Profit Formulas

• Profit = Revenue – Costs
• Revenue = Quantity * Price
• Costs = Total Variable Costs + Total Fixed Costs
• Total Variable Costs = Quantity * Variable Costs
• Profit = (Price – Variable Costs) * Quantity – Total Fixed Costs

Investment Formulas

• Return on Investment = Profit / Investment Cost
• Payback Period = Investment Cost / Profit per Year

Operations Formulas

• Output = Rate * Time
• Utilization = Output / Maximum Output

Market Share Formulas

• Market Share = Company Revenue in the Market / Total Market Revenue
• Relative Market Share = Company Market Share / Largest Competitor’s Market Share

General Statistics

• Global population: 8 billion
• Average household size: 2.5 people per household
• Average life expectancy: 80 years

Country Population Statistics  

• United States: 320 million
• Canada: 40 million
• Mexico: 125 million
• Brazil: 200 million
• United Kingdom: 60 million
• Germany: 80 million
• France: 60 million
• China: 1.4 billion
• India: 1.4 billion
• Russia: 150 million
• Japan: 125 million
• Australia: 25 million

Tip #1 - Make sure you understand the business problem and objective : Answering or addressing the wrong business problem is the quickest way to fail a case interview.

Tip #2 - Don’t rely on using memorized frameworks : Interviewers can tell when you are regurgitating memorized information and not thinking critically.

Tip #3 - Structure your approach before doing any math calculations : This helps you avoid making unnecessary calculations or reaching a dead-end.

Tip #4 - Talk through your calculations out loud : This decreases the likelihood of making a mistake and helps the interviewer follow what you are doing

Tip #5 - Structure your answer to qualitative questions : Use a simple two-part framework such as internal/external, short-term/long-term, or economic/non-economic.

Tip #6 - Answer “so what?” after every question : Throughout the case, connect each of your answers back to the case objective. What implications does your answer have on the overall business problem?

Tip #7 - Have a firm recommendation : Do not have a flimsy recommendation that switches back and forth between two different recommendations. Pick one and provide support.

Tip #8 - Be 80/20 : You will not have time to answer every single question. Focus on the most important questions that have the greatest impact on your answer. This is the 80/20 principle which states that 80% of the outcome comes from 20% of your effort.

Tip #9 - Be coachable and easy to work with : Interviewers look for people that they would personally want to have on their team. Demonstrate that you would be a great teammate.

Tip #10 - Be enthusiastic : Interviewers want to hire candidates that love their job and will work hard. Displaying enthusiasm shows you are passionate about consulting and working at the firm.

Check out our complete list of case interview tips .

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• Hacking the Case Interview Book   (available on Amazon): Perfect for beginners that are short on time. Transform yourself from a stressed-out case interview newbie to a confident intermediate in under a week. Some readers finish this book in a day and can already tackle tough cases.
• The Ultimate Case Interview Workbook (available on Amazon): Perfect for intermediates struggling with frameworks, case math, or generating business insights. No need to find a case partner – these drills, practice problems, and full-length cases can all be done by yourself.

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Case Interview 101: The Online Guidebook

“Case Interview” is the cornerstone of consulting recruitment, playing a decisive role in final results. In 30 minutes, your “consulting” qualities will be tested to the limit as you cruise through a hypothetical “consulting project” with the interviewer.

Yes, this is a BIG topic. The depth of content in this single article is HUGE with various chapters ranging from beginner’s topics to more advanced ones. You would want to bookmark this page and go back often throughout your whole preparation journey.

What is a case interview?

A case interview is a job interview where the candidate is asked to solve a business problem. They are often used by consulting firms, and are among the hardest job interviews, testing both problem-solving skills and “soft” skills. Case interviews often last 30-45 minutes each, and firms can utilize up to 6 case interviews, usually divided into 2 rounds.

Example case questions:

• “We have a restaurant called “In-and-out Burger” with recently falling profits. How can you help?”
• “The CEO of a cement company wants to close one of its plants. Should they do it?”
• “A top 20 bank wants to get in top 5. How can the bank achieve that goal?”

Case interviews are modeled after the course of actions real consultants do in real projects – so success in case interviews is seen by consulting firms as a (partial) indication of a good management consultant.

During the interview, the interviewer will assess your ability to think analytically, probe appropriate questions, and make the most client-friendly pitches. Be noted that the analytical thought process is more important than arriving at correct answers.

Generally, there are 2 styles of conducting cases:  Candidate-led and Interviewer-led. 

Candidate-led cases

On this end, the interviewer rarely intervenes; the candidate will lead the approach from structuring the problem, drawing frameworks, asking for data, synthesizing findings, to proposing solutions. This format can be difficult for beginners but it provides you with much control over the case.

Interviewer-led cases

On this end, the interviewer controls the process in significant ways. He or she has the candidate work on specific parts of the overall problem and sometimes disregards the natural flow of the case. The game here is not to solve the one big problem, but rather to nail every question, every pitch, every mini-case perfectly. Because the evaluation is done on a question basis, the level of insightfulness required is higher.

Most cases will fall somewhere in the middle section of that spectrum, but for educational purposes, we need to learn case interviews from both extremes ends.

Great details in each and every aspect of the case, as well as tips, techniques and study plans are coming in the chapters below. You may skip straight to Chapter 3 if you have business background and confidence in your own understanding of the terminology used in case interviews. 

To better understand or practice candidate-led and interview-led cases, let’s book a personal meeting with our coaches . At MConsultingPrep, you can connect with consulting experts who will help you learn the ins and outs of both cases and the solving approach to each one. Get “real” practice now!

Case interview starter guide for non-business students

All consulting firms claim that all educational backgrounds have equal chances. But no matter what, case interview reflects  real-life business problems and you will, therefore, come across business concepts .

Not everybody has the time to go to a full Business Undergraduate program all over. So through this compact Chapter 2, I will provide you, the non-business people, with every business concept you need in case interviews.

Accounting and financial terms – The language of business

Accounting & Financial Terms are often called the language of business, which is used to communicate the firm’s financial and economic information to external parties such as shareholders and creditors.

There are three basic financial statements : Balance Sheet, Income Statement, and Cash Flow Statement.

Balance Sheet

A snapshot of the current stage of the company’s property, debt, and ownership at one given point in time, showing:

• Assets: what the company owns: Building, Equipment, Cash, Inventory, along with some other intangible items.
• Liabilities: what the company owes: Loans, overdrafts, bills to be paid, etc. Debt is like negative assets.
• Equity (Net worth): Calculate by taking Assets subtract Liabilities.

The neat thing about the Balance sheet is that it’s always balanced. Every action, every transaction changes the three components but it’s always in harmony.

Income Statement

A record of the business performance through a period of time , given it a quarter or a year. The Income Statement directly tells you how the company is doing in terms of making money, the heart of any business.

From the top to bottom, the Income Statement shows the Revenues, Costs, and Profits. That’s why often, Profits are referred to as the “bottom line”.

There are a few types of costs to notice – see the two pictures below this table.

One important thing to notice is that even though it may seem like, the Income Statement does NOT necessarily relate to cash. Many times, especially for B2B transactions, the selling happens before the money flow. Therefore, we may have to record revenue without having the cash.

Cash Flow Statement

There’s a famous saying that: Income statement is an opinion, Cash Flow statement is a fact.

The Cash Flow statement just strictly monitors the cash flow in or out, categorized into different sections. Three of them are:

• Operation: illustrates how much cash the company can generate from its products and services.
• Financial: includes the sources of cash from investors or banks and the uses of cash paid to shareholders.
• Investing: includes any sources and uses of cash from a company’s investments.

Upon completion this section, you should be able to read and interpret financial statements for business diagnosis and decision-making.

More importantly, you possess the conceptual base to start solving case interviews on your own. Do not forget that, as with any other language, becoming proficient with accounting and financial terms require constant practice.

Organizational structure – The heart of a company

When it comes to organizational structure, it is important to notice the fine line between the company’s ownership and management .

Technically, at the highest level, there are shareholders . For private companies, the group of shareholders and their shares are not necessarily disclosed and publicly tradable. For public companies, on the other hand, shares are publicly traded on different stock exchanges. One of the most famous is the NYSE, which stands for New York Stock Exchange.

• A company can have one, a few, or millions of individual owners, but being governed by the Board of Directors – a group of people elected by owners, with the President or Chairman being their highest leader.
• The Board usually hires a management team to manage the company. They are led by the Chief Executive Officer – CEO , who makes every decision on day-to-day work. Most of the time, the Board of Directors doesn’t directly intervene in the CEO’s work, but they reserve the right to fire CEOs.
• Besides that, there’s a committee called Supervisors. The supervisor’s job is to independently monitor the CEO and the management team and report to the Board.

Below CEOs, there are two general two ways of structuring the company. One way is through business lines and the other one is through functions. Think of business lines as mini-companies themselves inside the big company.

Within functions, here are a few most typical divisions most companies have:

Business strategy concepts

Even with business students, strategy is a challenging topic – especially with those without a strategy major. These fundamental concepts will get you started.

• Organization: In general, this refers to how a company is organized, what are different components that make up a company
• Governance refers to how a company is managed and directed, how well the leader team runs. The leader team includes the Board of Directors and Board of Managers. A company with good governance has good leadership people, tight control, and effective check & balance processes, etc.
• Process looks like rules and common practices of having a number of processes, entailing every single activity. Process design should include 4 factors: who, what, when, and accompanied tools.

For example, let’s look at Kim’s family picnic process.

• The who part is presented on the y-axis, left-hand side, labeling all departments, a.k.a: family members, involved.
• The what part is presented through the big mid-session with each box represents every single activity.
• The when and tools parts are presented at the bottom

B2B  vs B2C : stand for “business-to-business” and “business-to-customer”. These two terms refer to two types of transactions a company typically does: transactions with other companies and transactions with individual customers.

Bottom-up vs Top-down: this refers to two opposite schools of thought or action. Top-down usually encompasses various general branches while bottom-up tends to narrowly focus. 

Management consulting terms & concepts

These are the most common consulting terms you may encounter not just in case interviews but also in consulting tasks .

• Lever: Think of this as one or a group of initiatives, actions to perform to meet certain goals. e.g. some levers to help increase customer experience in a hotel are free breakfast, free Wi-Fi, 24/7 support, etc.
• Best practice: Refers to how things should be done, especially if it has been successfully implemented elsewhere.
• Granular: This refers to how specific and detailed a break-down or an issue goes. For example, a not-so-granular breakdown of the NBA is the West and the East conferences. A much more granular is something like this: Leagues, Conferences, Divisions, and Teams.
• MECE: MECE is so important and we explain it in detail in this article. In short, MECE is the standard, per which we can divide things down in a systematic, comprehensive, and non-overlapping way.

There are three parameters the consulting world uses in the categorization of businesses.

• Industry: used to group different companies mostly based on their product (Banking, Construction, Education, Steel Industry, etc.)
• Function: is the categorization mostly based on missions and the type of roles of different parts of a company. We can count some as Human Resource, Finance, Strategy, Operation, Product Development, etc.
• Location: is where things are, geographically.

Normally two consultants ask each other “What do you work on?”, they need to give 3 pieces of information in all of those three parameters, such as “I worked on a Cement project, focusing on Finance, in Southeast Asia”. In fact, all of the McKinsey support networks are organized in this way. During my projects, I would need to speak to some Cement experts, some Finance experts, and some local experts as well.

This chapter is relatively long, yet it is still way shorter than 4 years at business college. I hope this will act as a great prerequisite to your case interview study. Make sure that you have mastered all of these content before really tackling the Case Interview.

Case interview example – The typical flow

In a simplified way, a typical case would go through these phrases (we will talk about exceptions in great detail later):

Case question -> Recap -> Clarification -> Timeout -> Propose issue tree -> Analyze issue tree -> Identify root-causes -> Solutions -> Closing pitch

Problem-solving fundamentals – Candidate-led cases

Though most cases will be conducted in mixed format, let’s dive deep and learn about each extreme end of the spectrum to get the full picture.

Even though this is the harder format, it shows us the foundation of how management consulting works, i.e: the consulting problem-solving logics!

If you were exposed to case interviews, you have probably heard about some of these concepts: framework, issue tree, benchmark, data, root cause, solutions, etc. But how do they all fit into the picture?

It all starts with the PROBLEM

Before getting into anything fancy, the first step is to define and be really clear about the problem.

This sounds easy but can be quite tricky. Here are a few guidelines:

1. What’s the objective?

2. What’s the timeline required?

3. Any quantified or well-described goals?

For example, one client can state a problem as: “I lost my car key”. In normal contexts, this is a perfectly simple and straightforward problem. But a consultant tackling this would go ask clarification questions to achieve even more details:

1. Objective: the client in fact just needs to be able to use the car.

2. Timeline: this is an urgent need. He is happy only if we can help him within the next hour.

3. Specificity: help the client put his car into normal operation like before he lost the key.

Find the ROOT-CAUSE, don’t just fix the symptom

To completely wipe out the problem and create long-lasting impacts, consultants always  search and find the root causes.

For example, fixing the symptom is like you breaking the door lock, getting into the ignition electrics behind the wheel, and connecting the wires to start the car.

That does fix the surface symptom: the client can drive the car. But it does NOT create a long-lasting impact because without you there, the car can’t be started. The client will need to rely on you every single time. Plus, more problems even arise (now he needs to fix the broken door lock too).

A much better approach is to find the root cause. What is the bottom-line reason causing the problem? Once we trace, find, and fix it, the problem will be gone for good.

In this example, the root cause is “the lost key”. We need to find its location!

Use ISSUE TREE to isolate potential root-causes into groups

There could be thousands of possible root-causes. How do we make sure every possible one is examined? If we are to list out all thousands and test one by one, there is simply not enough time. On the other hand, if we just list out some of the most “possible” ones, we run a high risk of missing the true root-cause.

This is where we need issue trees ! We would group possible root-causes into big groups. Those big groups will have smaller sub-groups and so on. All is done in the spirit of top-down and MECE. By doing this, we have an organized way to include all possible root-causes.

Continue with the example: A “bottom-up” approach to search for the car key is to go straight to specific places like the microwave’s top, the black jacket pocket, under the master bed, etc. There can be thousands of these possible locations.

The top-down approach is to draw an issue tree, breaking the whole house into groups and examine the whole group one by one. For example: first floor, second floor, and the basement.

Issue Tree only works if it’s MECE

What happens if we break down the search area into the First floor and East wing? The search area would not cover the whole house and there will be some overlapping which creates inefficiencies.

So for an issue tree to work properly, it has to be MECE – Mutually Exclusive and Collectively Exhaustive … which in simple language just mean 2 things: no overlap and no gap

How to draw MECE issue trees? Use FRAMEWORKS!

Each problem requires a unique issue tree. Coming up with MECE and spot-on issue trees for each problem can be really difficult. This is where “framework” helps.

Think of frameworks as “frequently used templates” to draw issue trees in any particular context. Many people use the word “framework” to refer to “issue tree” but this is conceptually incorrect.

We will talk about frameworks in more detail in the below chapters. You can also check out this deep-dive article on Frameworks.

Choosing which branch to go to first? Use HYPOTHESES!

So let’s say you have an issue tree of First floor, Second floor, and Third floor. Now what?

To make the problem-solving process even faster and more efficient, we use hypotheses. In simple language, it’s the educated guess of where the root cause may lie in. So we can prioritize the branch with the highest chance.

So let’s say, the client spends most time on the first floor, it’s where he/she most likely leaves the car key. Any consultant would hypothesize that the root cause is in the first-floor branch and go search there first.

Notice: hypothesis and issue tree always go together. It doesn’t make sense to draw an issue of First, Second, and Third floor and hypothesize that the key is in the East wing. Many times, hypotheses are even the inspiration to draw issue trees.

How to test a branch? Use DATA and compare it with BENCHMARK

Now that we decide to test the branch “First floor”, how do we do that?

We prove or disprove our hypothesis by collecting DATA. That data is then compared with benchmarks to shed more meaning. Two main types of benchmarks are: historical and competitive. For example, let’s say by some magic, the client has a metal detection machine that can measure the metal concentration of any space.

To test the “first-floor” branch, the consultant would come to the first floor, measure the metal concentration and compare it with the data before the car key is lost, a.k.a: historical benchmark.

If a hypothesis is true, drill down; if it’s false, go sideways

What happens when we test a hypothesis?

Assuming that we have access to enough data, it either gets proven TRUE or proven FALSE. How do we proceed from here? 

• Proven True: go DOWN the issue tree to sub-branches! Let’s say the metal detector identified the key IS indeed on the first floor. Go deeper. Draw sub-branches of that first-floor branch and repeat the process.
• Proven False: go HORIZONTAL to other big branches! Let’s say the metal detector denies the key presence on the first floor. We then can cross out this branch and go test others, a.k.a: the second and third floor.

Test, Sleep, Test, Repeat … until the ROOT-CAUSE shows up!

Once identified the ROOT-CAUSES, go for SOLUTIONS

With all proven root causes identified, the last step is to come up with solutions to kill the problem … and we are done! There can be multiple solutions to each root cause. These solutions should attack straight to the root cause.

Case interview questions – Interviewer-led cases

While candidate-led cases are all about the logical foundation of problem-solving, interviewer-led cases are more about tackling each individual question itself. The structure of the whole case is relatively loose and flexible.

In this chapter, we touch on some of the most popular ones. You can read in-depth about each in this designated article.

Framework/Issue Tree questions

“Which factors would you consider when tackling this problem?”

This is one of the most popular question types in case interviews, often asked in the beginning. It comes with several shapes and forms, but the real meaning is always: “Give me the bloody issue tree!”

So how do you tackle it? Just like in candidate-led cases. Take a timeout; brainstorm about the problem and how it should be broken down into; plug a few frameworks to see how it looks; and go for the most appropriate issue tree.

Unlike in candidate-led cases where you only present the upper-most layer, here you should walk the interviewer through the whole issue tree, covering at least 2 layers. Interviewer-led cases are much less interactive. It’s more like they ask you a question, and you deliver a comprehensive and big answer. They ask you another one. And so on.

Market-sizing / Guesstimate questions

“How many face masks are being produced in the whole world today?”

This is among  the most popular question types and you will likely face a few of them throughout several interview rounds. These questions ask you to “guess” and come up with number estimations in non-conventional contexts. These questions are called “Guesstimate”.

When a guesstimate question asks you to “guess” the size of a market, it’s called a “Market-sizing” question. Though this variation is very popular in consulting, the nature is nothing different from other Guesstimate questions.

It can be intimidating to face a question like this. Where to start? Where to go? What clues to hold on to?

The key is to understand that you don’t have to provide an exact correct answer. In fact, nobody knows or even cares. What matters is HOW you get there. Can you show off consulting traits, using a sound approach to come up with the best “estimate” possible?

Read the designated article on this for great details. Here, let’s walk through the 4-step approach that you can apply to absolutely every market-sizing question.

Step 1: Clarify

Make sure you and the interviewer are on the same page regarding every detail and terminology, so you won’t be answering the wrong question.

Step 2: Break down the problem

Break the item in the question (number of trees in Central Park, market size of pickup trucks) down into smaller, easy-to-estimate pieces.

Step 3: Solve each piece

Estimate each small piece one at a time; each estimation should be backed by facts, figures, or at least observations.

Step 4: Consolidate the pieces

Combine the previous estimations to arrive at a final result; be quick with the math, but don’t rush it if you aren’t confident.

Math questions

“If the factory can lower the clinker factor by 0.2, how much money will they save on production cost?”

Almost all cases involve some math. So you will face math questions for sure. These “questions” can go at you either explicitly and implicitly. Sometimes, the case interviewer will ask out loud a math problem and have you solve. But sometimes, you have to do multiple calculations on the background to push the analysis forward.

Either way, a strong math capability will help you a lot during cases and the future career in consulting. See this Consulting Math article for more details.

Chart insight questions

“What insights can you draw from this chart?”

Consultant works with data and a big chunk of those data are presented by charts. Many times, the interviewer would pull out a sanitized exhibit from an actual project and have you list out insights you can see from it.

There are many types of charts. Getting yourselves familiar with the most popular ones is not a bad idea.

• Bar charts simply compare the values of items that are somewhat parallel in nature.

• Line charts illustrate the continuous nature of a data series, e.g: how my heart rate evolved through time.

• Pie charts illustrate proportions, i.e “parts of a whole” analyses.

• Scatter-plots use data points to visualize how two variables relate to each other. Correlation for example.

Tips on tackling chart-insights questions:

1. Read labels first: from Chart titles, Axis titles, Legend titles, etc. Don’t jump straight to the content of the chart. It takes more time to get lost there and has to go back to read the label. Besides, you may also run a risk of misunderstanding the content.

2. Look for abnormalities: important insights always lie in those unexpected and abnormal data. Look for them!

Value proposition questions

“What factors does a customer consider when deciding which car insurance company to buy from?”

In simple language, this question type asks you: what do the customers want? Understanding exactly this need will put any company in the best position to tailor products/services.

Like any other questions, Value-proposition questions are not only about correctly identifying customer preferences (insights) but also about analyzing and delivering the answer in a structured fashion. Here are a few tips for you to do that:

How to be more insightful: 

• It always helps to break customers into groups and provide different substances for each.
• Put yourselves into the customers’ shoes. Think from the first-view perspective and more insights will arrive.
• If there is any data/ information previously provided in the case, definitely use it.
• A library of factors? Safety, speed, convenience, affordability, flexibility, add-on services, durability, fashion, ease of use, location, freshness, etc.

How to appear more structured:

• Follow this structure: Customer group 1, Customer group 2, etc. Under each: Factor A, factor B, factor C.
• Develop your personal script for this question type. Make sure it’s easy to follow and structured in nature.

Information questions

What kind of data do you need to test this hypothesis? How do you get data

Consulting is a data-driven industry. As consultants, we spent most of our time gathering and presenting data to clients ( see the What the heck does a consultant do video ). No surprise information questions are relatively popular in cases.

The best way to tackle this question type is to understand inside out the types of data actual consultants use in real projects. Because almost no candidate knows about this. This is also a very quick way to build rapport. The interviewer will feel like he/she is talking to a real consultant.

Case interview example video – Pandora case

Enough theory! Enough cute little illustrations here and there. Time to get our hands into a serious case interview example.

Notice the following when watching the video:

• How the problem is given and clarified
• How the problem-solving approach is layouted and executed
• How the candidate use wording and frame the pitches
• The dynamic of a case. How energy transfers from one to another person.

Every case is unique in its own way but principles are universal. The more examples you see, the better. This video is extracted from our  Case Interview End-to-end Secrets program, where you can find 10 complete examples like this and many other supplement contents.

How to prepare for case interviews

Case Interview preparation is a long and tough process. In an ocean of books, videos, programs, how do we navigate to maximize learning? Most materials floating around are quite good, at least in terms of substance. But the timing and the organization of them can be confusing.

• Too much theory in the beginning can burn brain power very quickly.
• Tackling cases without basics can develop bad habits, which eventually cost more time to unlearn.
• Practicing complicated (or even just normal) cases in the beginning can destroy morale drastically.

So a good study plan is constantly switching between 3 activities: reading theory, watching examples, and practicing, with cases increasing difficulty level. It’s so crucial to start with super easy cases, be patient, and stay on that level until you are ready to move up. There are so many skills, habits, and scripts to develop and these take time.

“The quickest way to do just about everything is … Step by Step”

Even for candidates with cases coming up urgently, I still strongly recommend spending the most valuable time practicing cases that match your level. After all, cases are just the context. What you will be evaluated on is your approach, your skills, your techniques, etc.

So, this is a sample study plan you can adopt for yourselves:

Step 1: Learn the basics of case interview theory

• Read this article thus far
• Watch this  Case Interview 101 video

Step 2: Watch a simple case interview example

• Read the sample case flow above.
• Watch this  Case Interview Example video
• Go to this list of free case examples and try to select a very simple one. If you can’t follow one, it’s probably not good for you. Just skip it.
• Watch the first example in the  End-to-end Program

Step 3: Review the theory of case interview approaches  

• Read deeply about the logical foundation of problem-solving in this BCG & Bain Case Interview article.
• Watch intensively the logical foundation of problem-solving in this Candidate-led cases video.

Step 4: Do one mock case interview

• Practice with consultants. They have the insight and knowledge to help you pass the interview. Discover our experienced coaches from McKinsey, BCG and Bain here .
• Find a partner to practice with. Make sure you both watch this  Guide on how to conduct a case. A bad coach can do more harm than good.
• Get your hand on another example in the  End-to-end Program. But this time, don’t just watch. Actively solve the case as you see it! Try to say out loud your version, then listen to the candidate, then hear the feedback!

Step 5: Start improving your business intuition

Business Intuition is like your natural sense of the business world: how to be insightful and creative in various business contexts, how to feed the “content” into your approach, etc. Think of this as a basketball player trained for muscle strength, agility, or durability. Intuition can be improved gradually through constantly exposing yourselves to a wide range of business situations and contexts.

You can do this by:

• Read consulting publications. One article per day for example. Three wonderful sources are: McKinsey Insights, BCG Perspectives, and Bain Publications
• Train  case interview questions individually. By isolating each part of the case, you can focus more on the substance. Hit that link or get more question training on the End-to-end Secret Program .

Step 6: Start training consulting math

• Visit this in-depth consulting math article.
• Train our  Mental Math methodology.

Step 7: Practice another mock case interview

At this stage, please still stick to very basic cases. The goal is to see all of the knowledge and skills above in real action. Again, this can be done by either:

• Book a meeting with coaches
• Find another partner to practice with. Just make sure you both watch this Guide on how to conduct a case. A bad coach is always more harmful than not practicing at all.
• See another example in the End-to-end Program. Like the previous one, try actively solving the case as you see it! Say out loud your version, then listen to the candidate, then hear the feedback!

Step 8: Equip yourself with tips, techniques, and advance theory

• Read on! The below chapters of this very article will provide you with more advanced theory and killer tips.
• Watch the whole Tips & Techniques sections of the End-to-end Program. You will find 10 examples with clear walkthroughs of tips and techniques right in the middle of real action.

Step 9: Do further mock cases, review, and improve

Practicing for case interviews is a time consuming process – but as long as you have the right method, you will make it!

• First, brush up on knowledge related to case interviews with the Case Interview End-to-End Secrets Program .
• Second, get personalized practice with ex-consultants. That way, you’ll receive clear and tuned feedback to understand what to improve, building your own proper case approaches.  See a list of experienced coaches here .

Stay tuned with us on this website and our Youtube channel for continuously updated information on case interviews and management consulting recruitment; you can also subscribe to the newsletter below for free materials and other insightful content!

Good luck with your case prep!

Case interview tips – With instant results

Imagine a case interview just falls out of the sky and into your lap, scheduled for tomorrow – how can you even prepare?

The answer lies in a few “quick and dirty” tips, which I’ll share with you in a moment.

I am a firm believer in the 80-20 rule – which states that 20% of the causes lead to 80% of the consequences.

In the case interview prep context, 20% of your learning efforts will bring about 80% of the improvements – so the key to instantly and dramatically improving your case performance is to identify and focus on that 20%.

In the next 8 chapters, I’ll tell you the killer tips and tricks that helped me get a McKinsey offer, the majority of which were previously only available in the premium End-to-End Secrets Program , including:

• Chapter 9: Delivering the perfect case opening
• Chapter 10: Remaining absolutely structured throughout the case
• Chapter 11: Taking the best notes
• Chapter 12: Getting out if stuck
• Chapter 13: How to ask for data
• Chapter 14: What to do when receiving data
• Chapter 15: Deliver the most convincing closing pitch
• Chapter 16: Developing your personal scripts

One thing before you proceed: don’t forget to learn the fundamentals, the question types, and the frameworks. Remember, these 20% tips can only get you 80% performance; if you want 100%, there’s  no substitute for hard work.

How to deliver the perfect case opening

The result of a case interview is determined  the first 3 minutes – and I’m not even exaggerating.

Most people will be put off by this fact – indeed, with all those efforts spent on learning for the later part of the case, and the hiring decision is made when you’re not even properly warmed up yet.

However, putting a spin on it, this is the 20% to focus on – if you nail the opening, you’ll make a better impression than most candidates; it’s also easier to perform well in 3 minutes than in 30 minutes, especially when the case hasn’t gotten tricky. Additionally, you can prepare the opening in a formulaic manner – essentially learning by heart until it becomes natural.

There are 7 steps in the perfect case opening formula:

1. Show appreciation

2. Announce case introduction

5. Announce case approach

7. Ask for a timeout

In this chapter, I’ll walk you through each of those steps.

Step 1: Show appreciation

The quickest way to score the first points with any interviewer is to  sincerely compliment them. Everybody loves compliments.

Case interviewers are not dedicated HR staff, but Engagement Managers, Partners, and Directors who conduct interviews ON TOP OF their projects as goodwill for the firm, so you should at least be thankful for the time they spend with you.

Begin your interview with a sincere “thank you” for the interesting case (if you have to fake these words because deep down you don’t like case interviews, you aren’t exactly cut out for the job).

Step 2: Announce case introduction

Announce you’re going to do  steps 3, 4, and 5.

This step is related to what I call the “map habit”, which I’ll describe in detail in the next chapter. For now, just understand that it  helps the interviewer follow your introduction, and shows you’re a structured person.

Step 3: Recap  

What is the key question of the case?

On a side note: one common mistake is to mix up step 3 with step 4 (clarify) – remember, don’t ask anything , just rephrase the case to ensure that you get it right.

Step 4:  Clarify

Ask questions to clear up any  potential confusion about the details of the case.

Case questions are always very short with a lot of vague details; if you don’t see the need to ask anything, you’re doing it wrong.

Run this checklist through your mind to help you clarify as many unclear points as possible:

• Definitions: are there words you don’t understand or can be interpreted in multiple ways?
• Timeframe: what is the “deadline” for solving this problem?
• Measurement: how are the important variables (performance, revenue, etc.) measured?

Additionally, number your questions so it’s easier for you and the interviewer to keep track.

Step 5: Announce case approach

Roughly sum up  how you’ll analyze the problem.

Again, this is related to the map habit, which makes the overall case progress easier to follow.

There are 3 types of cases: (1) problem-solution, (2) should I choose A or B, and (3) how to do C. For each type, there is a different approach. The latter two are discussed in the “Advanced Logic” chapter, for now, we’ll continue with the first type: tell the interviewer you’re going to find the root cause to ensure long-lasting solutions, and to do that you’ll develop an issue tree.

Step 6: Align

Check if the interviewer  approves of your case approach.

This is an important habit of real consultants  because nobody wants to waste resources going in the wrong direction; interviewers expect candidates to show it in the case interview.

Simply ask “Does this sound like a reasonable approach to you?” – most likely the interviewer will give you the green light, but if you’re lucky he/she may even suggest a better approach.

Step 7: Ask for timeout

After you’ve gone continuously through the 6 steps above, ask the interviewer for timeout to (make this explicit) gather your thoughts and develop the first part of the issue tree.

Make the most of your timeout session, and keep it as short as possible. Any unnecessary silence will damage the impression and hurt your chances (refer to the End-to-End Program example in Chapter 6 to “feel” how awkward a lengthy timeout session is).

Case opening – Example script

Now it’s time to see how you can put all those steps into action!

Thank you for this very interesting case, I am really happy to get a chance to solve it!

The first step in solving any business problem is to make sure we solve the right one, so before diving into the problem, I would like to first recap the case, then ask a few clarification questions to make sure we’re both on the same page, and lastly announce my overall case approach.

So here is my understanding of the case:

• [facts regarding the client and situation]
• [key case question]

Does that correctly summarize the case?

<assume the interview confirms that your playback is correct>

Great, now I’d like to ask my three clarification questions:

• [question 1]
• [question 2]
• [question 3]

<wait for answers>

Thank you for the clarification. Is there anything else I should be aware of?

Thanks for all the insights. It’s great that we all agree on the key details.

For the overall approach to this case, to completely wipe out the problem for a long-lasting impact, we will need to find out the root causes of this problem. To do that I will try to break the problem down into bite-size pieces with issue trees, in order to quickly isolate the root causes inside the branches, then drill down accordingly to gather information until we can draw actionable solutions.

So before I go on to establish my first issue tree, does that approach sound reasonable to you?

<assumes the interviewer agrees with your approach>

It’s great to see that we’re on the same page regarding the key details as well as the overall approach to the case. I do need some time to gather my thoughts, so may I have a short timeout?

Being structured throughout the case

The high stress and large amount of information in case interviews make it easy for even the brightest candidates to derail from the objective or present in an unstructured manner.

I’ll be sharing with you my 3 most impactful tips for keeping the structure in case interview:

1. The map habit

2. Numbering your items

3. Sticking to the big problem

The map habit

It means regularly and explicitly checking where you are, and where you’re doing next.

I call it the map habit because it’s similar to using a map while traveling – pausing every once in a while to check your location, destination, and direction.

This habit gives you a sense of direction and authority while making it easier for the interviewer to follow your case progress. It also makes you sound organized and systematic – a definitive mark of management consultants – and the interviewer will love it!

You’ll see this habit a lot in our Case Interview End-to-End Secrets Program, where candidates would often pause at each key step during the case. Do the same thing in your own case interviews, and you’ll greatly impress the interviewer.

Numbering your items

A very easy and effective way to make your pitches sound structured is to number each item.

The formula is simple: “There are X items that I’m going to say; they are: No.1 … No.2 … No.3 …”

By now you may have noticed that I use this structure many times throughout this guidebook – it’s already quite effective in written language, but it’s even more impactful in spoken communications!

Having this numbering habit will make it very easy for the listener to follow your speech, and it creates an impression of MECE (even if content-wise it’s not MECE).

Sticking to the big problem

There are two ways to keep yourself on track  all the time in those high-stress case interviews

1. Occasionally check your position on the issue tree, and quickly get back on track if it seems you’re “derailing”. If this sounds like the previous map habit, you’re right, it is the map habit.

2. Take good notes, with the case question being written big and bold on top of your scratch paper. That way you’ll be reminded every few seconds.

That last point brings us to the next issue: how to take notes.

How to take notes in case interviews

The best notes for case interviews are always  clear-cut, structured, and relevant.

Even the smartest candidates suffer from seemingly silly problems in case interviews – forgetting data, messing up the numbers, getting stuck with frameworks, losing sight of the original objective, etc. And in the true management consulting spirit, I set out to find the root causes.

And looking back at hundreds of coaching sessions I did, I found one thing in common – none of those candidates could take good notes.

I’ll tell you precisely how I took notes to get a McKinsey offer; however, I hope that after this chapter, you can install the spirit of the method, not just the method itself.

So here we are, with the 3 groups of sheets laid out for the ideal note-taking:

1. Data sheets

2. Presentation sheets

3. Scratch sheets

Data sheets

Data sheets are used to store and process every piece of incoming data .

Try to draw tables for these sheets, because this not only makes the calculation process easier but also gives the impression that you’re a careful and organized person.

Also, remember to write only the results of calculations on this sheet, to keep it neat and tidy. Most of your calculations should be done mentally (see the article on Consulting Math for more details); if you really need to jot down the calculations, do it on the scratch sheets.

Presentation sheets

Presentation sheets are used to develop and present any “outgoing” content.

Your issue trees should be drawn on these sheets, along with the big-and-bold case question/objective right on top. When delivering your pitches, always turn around the presentation sheets so the interviewer can clearly read what’s on them.

As with the data sheets, avoid any messy “mid-process” drawings. Put them on the scratch sheets instead.

Scratch sheets

Scratch sheets exist to keep other sheets clean.

Ever felt irritated receiving a notebook full of correction marks? That’s exactly how the interviewer feels if you present with untidy notes. You should try your best to hide all the unorganized, messy parts of your thought process.

The scratch sheets provide a sanctuary for that unstructured part of yours – it’s okay to go all over the place for brainstorming, as long as you can organize the incoming resources and present in a systematic manner.

“I took the notes just as you instructed, but I still get stuck in cases. How can I avoid it?” – Well, that’s the subject for our next chapter – “Stuck” situations and how to get out of them.

Stuck in cases – What to do

We’ve all been there – that scarily awkward feeling when you don’t know what to do next in a case interview, that fear of being rejected.

In every “stuck” situation, the most important thing is to remain calm and collected (you’ll lose points if you panic) – then methodically work your way out. I’ll teach you how to get out of those situations, with style.

There are actually 3 different kinds of “stuck”, and for each, I have a different solution:

1. The “Framework” stuck

2. The “Data” stuck

3. The “I-Cannot-Find-The-Problem” stuck

Let’s go through each in detail.

The framework stuck

This situation happens when the candidate does not know which framework to use, and the secret tool for it, is “segmentation”.

Segmentation works just like any framework, and like a Swiss Army knife, it’s usually safe and easy to use. So if you’re unsure how to break things down, say these magic words:

“At this point, I’d like to break down this X item, and one good way is to use the natural segmentation within this line of business. So may I ask how they break this X item in this industry?”

If you get it right, the interviewer will reply with the most industry-relevant way to segment the item.

You may be wondering why I’m not talking about issue trees and frameworks here, after all the theory at the beginning of the guidebook.

The answer is that the textbook and “ideal” solution – learning the problem-solving fundamentals and deep-diving the frameworks to increase your flexibility – takes a lot of time, while the “cliched” solution – learning as many frameworks as possible, usually at the cost of depth – is inherently dangerous.

The data stuck

The “data stuck” happens when the candidate can’t extract relevant insights from the given data. And when this happens, ask for benchmarks.

Comparing with benchmarks is the quickest way to put data into perspective, yielding useful insights. There are 2 kinds of benchmarks – if you remember from the chapter on Candidate-led Cases: 

• Historical benchmarks: data on the same entity in the past
• Competitor benchmarks: data on similar/competing entities in the same timeframe

To ask for benchmarks, Just say the following lines:

“For now, I hypothesize that the root cause of the problem comes from the X branch of this issue tree. However, to further break down the problem in a spot-on way, I do need some information on the context of our client’s problem.

One of the quickest ways to grasp that context is to use competitor’s data; so can I have the X figure for our client’s competitors?”

The “I-Cannot-Find-The-Problem” stuck

This is the scariest “stuck” because there’s no obvious reason or solution – you’ve done your math right, your framework is suitable, and you’ve got a lot of interesting insights from data. Why are you still stuck?

From my experience in coaching sessions, there are 2 scenarios where this happens: (1) your issue tree is not MECE, and (2) if your issue tree is MECE, it does not isolate the problem.

You can try to avoid this in the first place by mastering the MECE principle, improving intuition, as well as aligning with the interviewer early and often.

But what if you still get stuck? The answer is to calmly admit you’ve hit a dead-end, and ask for time to fix the problem; be it the first or second scenario, you have to redraw your issue tree.

Literally use the following script:

“My whole analysis seems going towards a dead-end, which means either part of my issue tree is not MECE or my method of breaking down does not isolate the problem. Either way, I would like to take a timeout to have a look at it.”

You likely get stuck when practicing on yourself. That’s the reason why you need personal coaching. Veteran coaches at MConsultingPrep will give insightful feedback, propose actionable steps, and help you significantly enhance your performance. Find my coach !

How to ask for data

Data is the fuel for the case interview engine. Without it , your analysis can’t progress.

The problem is that interviewers don’t simply give out precious data for free. It has to be earned. There are 4 tips you can use to show that “worthiness”, and prompt the interviewer to supply you with the best information:

1. Create a good impression

2. Explain the purpose of the data

3. Explain the method of acquiring the data

4. Ask open-ended questions

Tip 1: Creating a good impression

The interviewer will love you if you think and act like a real consultant – if you can achieve that, he/she will always give you the best pieces of data available.

In this guidebook, there are countless tips to show your consulting characteristics – I even write a whole chapter on how to install consulting culture into your own personality. Generally, you must always be (1) structured , (2) fact-based, and (3) action-oriented.

Additionally, common people skills and interview tips also apply – show your appreciation by thanking for their help, keep a smile on your face to maintain a positive atmosphere, etc.

Tip 2: Explaining the purpose of the data

Say why you need that data, so the interviewer knows you can actually use it.

There are only two purposes for data in case interviews: (1) to test a hypothesis, and (2) to understand the context.

You can use the following scripts to when to reason your data requests:

“For now, I’m hypothesizing that the root cause of this problem comes from the X branch. Since this hypothesis can only be tested with the data on X, may I have those figures?”< testing hypothesis>

“For now, I hypothesize that the root cause of the problem comes from the X branch of this issue tree. However, to further break down the problem in a spot-on way, to better understand the context of our client’s problem, I will ask a few more questions. Does that sound reasonable to you?” < understanding the context>

Tip 3: Explaining the method to acquire the data

By stating how to get the data, you prove its feasibility and reinforce your data request.

In real consulting projects, data is not always available; the interviewer may rely on this logic and refuse to give you any information. So, when you ask for data, make sure your request is realistic, then state the method to acquire it using these words:

“If this was a real project, this information can be acquired from/by X source/method”.

In our  Prospective Candidate Starter Pack ,   there is a sheet listing all the possible sources of information in consulting projects, which you can download for your own use, along with many other free case interview materials.

Accurately explaining the data acquisition method also shows that you’ve done your homework and you know the consulting industry inside-out. Any interviewer will be greatly impressed.

Ask open-ended questions

This prompts the interviewer to give you data you haven’t thought of.

The precise questions mostly depend on specific cases (meaning you need to sharpen your intuition), but there is a Swiss Army knife here: “Is there anything else?” – which is a question real consultants ask several times a day, at the end of their conversations.

Use open-ended questions when you feel you might be missing something – for example, during clarification – and only after a series of well-defined, close-ended questions. Otherwise, you risk appearing lazy and over-reliant.

What to do when receiving data

Suppose the interviewer agrees to give you data. Now what?

Time to shine! If you do these following 3 steps, even just once, in the interviewer’s mind, you already pass:

1. Acknowledge the data and show appreciation

2. Describe the data, especially its notable features

3. State the implications of the data

Let’s dive into each separately.

Step 1: Acknowledging the data

Simply  thank the interviewer for the interesting piece of data.

Firstly, it confirms that you have received, and can understand the data.

Secondly, it’s always good to give out modest, subtle compliments to the interviewer. Trust me, conducting case interviews is hard work, and the interviewer does appreciate those little compliments.

Last but not least, it buys you a few seconds to fully absorb the new information and minimize any possible silence.

Step 2: Describing the data

Summarize  the most important insights you can extract.

Don’t recite a short essay about the data, there is no time for that. Quickly and mentally calculate all the important points, then state it out loud in 1-2 sentences.

This step has several uses:

It showcases your consulting math skills (chart insights and mental calculation)

It eliminates the silence during your analysis

It helps you quickly memorize the key trends in the data

Step 3: Stating the implications

Concisely explain how the insights from the data  related to the issue tree – do they confirm or reject the current hypothesis? Do they open new areas for investigations?

This part is extremely important because it connects to the action-oriented mindset of actual management consultants while laying solid foundations for your next steps (fact-based).

Example – Handling revenue data

Suppose you’re working on a profitability case (how to fix low profits), and you’re trying to dictate whether the root cause comes from the revenue side.

The interviewer gives you this data:

How would you respond? Try to answer it yourself before revealing the sample answer.

Sample Script - Receiving Data 

Thank you for the very interesting data. (acknowledging)

It seems that our client’s revenue has been increasing steadily throughout four years – around the mark of 20% annual growth, in fact. (describe the data)

This suggests that the problem may not come from this side of the issue tree. However, in order to fully reject the possibility, I need the figures on the revenue of other companies in this industry around this time. Do we have those numbers? (implications)

Delivering the perfect closing pitch

“You have one minute to summarize all of your findings to the client CEO. What would you say?”

Your answer must be short, to-the-point, action-oriented, and client-friendly.

The closing pitch of the case interview is sometimes called the “elevator pitch” , where you supposedly meet the client CEO inside the elevator and must somehow deliver the results of the project before the elevator arrives at its destination floor (it’s even worded like that sometimes).

Regardless of the wording, the principles remain the same, and your closing pitch must consist of these 4 parts:

1. Introduction / Lead-in

2. Summary of the root causes

3. Summary of the solutions

4. Next step

Part 1: Introduction / Lead-in

Open your pitch in a client-friendly way. Remember, consulting is a service – a premium one, in fact.

There is a simple formula for this part of the pitch:

“Mr. CEO, it has been a great pleasure to be working with you on your company’s X problem.”

Everybody loves a little compliment, don’t they?

Part 2: Summary of the root causes

Don’t go into detail about your analysis – show them the results first.

CEOs are busy people, they have no time for a 15-minute break-down of your issue tree. They only care about the “big picture” – “Why is the problem happening?”.

You need to sum up root causes in a structured manner, with a numbered list – in the case interview context, that’s one characteristic the interviewer looks for, and in real projects, it helps the listener follow your pitch.

“After careful analysis, we have found X root causes for the company’s problem: 1… 2… 3… X”.

Part 3: Summary of the solutions

The solutions are what the clients pay for in the first place, so make sure to deliver them clearly and systematically.

This step must also be structured. Additionally, list the solution in the same order as their corresponding root causes, to imply the connection between them (if the root causes are listed as A, B, C, then the solutions should never be C, B, A).

“To solve the aforementioned issues, we propose the X following solutions: 1… 2… 3… X”.

Part 4: Next step

The ending must lead the customer towards a follow-up project, in a client-friendly way.

This step shows that you have an action-oriented mindset and necessary people skills to represent the firm before the clients.

Moreover, follow-up implementation projects are a major source of revenue for the top consulting firms (such as McKinsey, BCG or Bain), so mentioning them in your case interview ending pitch proves that you did the appropriate research before applying.

So here’s what you’ll say when the elevator reaches the destination:

“We would be more than happy to work with you to implement these solutions”.

Develop personal interview scripts

Every tip I’ve mentioned in the previous 7 chapters is for recurring situations in case interviews, and they can be dealt with using formulaic responses.

What that means for you – the candidate – is that you can make personal scripts and learn them by heart until they all become your second nature. That will save you a lot of brainpower to use on the issue tree. This approach has proven successful with all of my coachees, and it’s also a major part of our Case Interview End-to-End Secrets Program. You will find my own personal script I used back in the day, and I will also personally give feedback to scripts of members of the program.

So open your document tool and start writing now. Once you’ve finished the scripts, learn them by heart one at a time. When you feel comfortable with every one of them, you can move up to a higher level and practice with whole cases.

Inside the case interviewer’s mind – Consulting culture

The best way to impress your consulting interviewer is to act like a consultant. And to do that, you need to know what goes on inside their mind – both the conscious and unconscious – then install it into your own personality.

In this chapter, I’ll guide you through 15 ingredients that make up a consulting mind. However, I won’t tell you how to apply this in case interviews because it will sound fake – what you need is to immerse yourself in a consulting environment, and incorporate these “ingredients” into your own mindset.

Responsibility & proactivity

Everyone talks about responsibility and proactivity these days, but in management consulting, we have a much more powerful word – “ownership” . When you “own” the work, you deeply and sincerely care about it, and you always try to go beyond what is required.

If you ever spend your efforts trying to improve a piece of work that your boss already approved, just because you know it is the right thing to do, because you feel so good seeing a job well-done, you have that “ownership” mindset.

In management consulting, you are expected to possess that mindset. In my early days at McKinsey, I was almost thrown out the window for working on a cement project but not knowing where the aggregate mines were (which was outside my responsibilities, but my boss expected me to know it, since I “owned” that cement project).

If you fail to do your work, don’t ever blame anyone or anything. Your responsibility is to draw up contingency plans for the “worst-case scenarios”:

• Missing the deadline because the client did not send you the data? You should have accounted for it in your schedule. 
• Late for work because of a traffic jam? Why didn’t you get up earlier?
• Your pet bite your suit? Any sensible person should have a spare one; even if that one is bitten, aren’t we paying you enough to get a new suit at the store this morning?

In short, if you want to be a consultant,  don’t make excuses.

Result-oriented / Can-do attitude

“There’s nothing I can’t do” – that’s the mindset you need to work in management consulting.

The result orientation inside a consulting firm is intense – saying that it’s “Mission Impossible” everyday would not be an exaggeration, but at the end of the day it’s always “Mission Accomplished”.

The boss doesn’t pay much attention to how you do a task, or what resources it takes, as long as you get it done. The firm has enough resources of every kind to help you with that, so there’s no reason you can’t pull it off.

Top-down communication

Communications made by consultants are always short, concise, to-the-point, action-oriented, and structured.

We were all given full-on lectures by our parents back when we were kids, for wasting food or not exercising (or not studying, for Asians like me). If they were management consultants, most of those lectures would be replaced with powerful, action-oriented messages: “Go study. If you don’t get an A+ for the next test, I’ll have to discipline you”.

A consultant seeing something non-MECE is like your mom seeing your messy bedroom. It’s that discomforting.

If you wish to be a consultant, train yourself to be MECE in everything you do. Once you can be MECE effortlessly, and you start spotting the annoying non-MECE-ness in everything around you, you know you’ve got it. 

If you’re unstructured, you won’t get into the business.

Being “structured” is a pretty vague concept, but everyone in the consulting industry knows when they see it. It’s about being organized, logical, top-down, MECE, etc.. Basically, if you can approach things the same way as real consultants, you will be deemed “structured”

If you can’t meet the deadline, you’re dead (of course, not literally).

A consulting firm works like the perfect machine, where every part operates as intended. When consultants promise to help you with something, you can be nearly 100% sure that they’ll keep their word. This makes work management that much easier.

Consequently, if you start missing the deadlines, you’ll be out of the game soon enough.

Manager from Day 1

You’ll get the idea right away if you watched this video on the job of management consultants:

In short, even as an entry-level associate, you’ll be managing a multitude of resources (experts, specialists, etc.), contents (reports, client data, expert knowledge,…), and stakeholders (the two most important being your client and your boss).

Pulling all of these together to create impactful results would be an impressive feat, even for the best and brightest new hires.

Client first

Don’t. Ever. Piss off. The client.

Management consulting is a special service industry – besides the usual “don’t disrespect the client” and “don’t leave a bad image of the firm”, there’s also “don’t make them hate you while telling them to do what they probably hate.” (which is a good way to sum up a consultant’s job).

In case interviews and PEIs, the interviewer will be asking himself a big question: “Can I trust this guy to represent me and my firm before the client?” – if the answer is anything below a stellar impression, you won’t be receiving an offer.

Consultants will have valid reasons for everything they do.

In both consulting work and case interviews, you need to be very explicit about the basis of your actions – every conclusion must have backing data, every idea must be explained, and every request must serve a purpose. Don’t ever assume that you’re justified.

Being fact-based is part of the foundation for the trust people place in consulting firms, so people who draw ideas out of thin air and act impulsively will never get into the industry.

Effective time & resources management

Every consultant works hard, so the only way to stand out is to work smart.

Yes, I know it’s a buzzword, and I know it’s cliched, but the 80-20 rule really does apply in this line of work. The best performers are always the ones to identify the most important lever and focus on it.

With the intense workload and up-or-out policy at major consulting firms, this skill is vital. Don’t be surprised if you pull all-nighters and work hard all the time but still get fired, while that one guy who goes home at 5 gets promoted. If you want to survive, learn from him.

Key takeaways & key messages

To a management consultant, everything has a key takeaway.

Consultants are efficient people, they don’t simply waste time, effort, and resources on irrelevant things. Things are only worthy of their attention if they have an interesting, helpful “so what”:

• You tell a story? So what?
• You perform a data analysis? So what are your key insights, and what’s the implication?
• You draw a slide? What’s the key message you’re trying to deliver?

If you already think like this, trust me, the interviewer will love you.

Think on your feet first

You should only ask for leadership assistance only  after you’ve thought well about the problem.

Just pause for a second and think: would you be more ready to help someone who really tries their best at the job or someone who does nothing and relies solely on you?

The same thing is true in consulting work, and even in case interviews: the interviewer will assist you if you can deliver well-informed opinions.

With that said, “asking without thinking first” is a very common mistake in case interviews, which you can see in the numerous examples from our End-to-End Secrets Program. 

Align early, align often

Always try to reach and maintain a consensus with co-workers and your boss, from the most mundane tasks to the largest projects.

Nobody wants to spend a whole week building a model that the team doesn’t need; it’s a huge waste of time and resources. As such, consultants have this aligning habit very early and often – a little time spent on reaching an agreement now will save a lot of trouble later.

Remember to align in case interviews as well – at the start of the case, and every important step.

Consultants are very action-oriented people who always think about the next step.

Every meeting, phone call, even random catch-up must end with everybody being explicitly and absolutely clear about what to do next.

So what’s YOUR next step, after reading this guidebook?

Scoring in the McKinsey PSG/Digital Assessment

The scoring mechanism in the McKinsey Digital Assessment

Related product

Case Interview End-to-End Secrets Program

Elevate your case interview skills with a well-rounded preparation package

Six types of charts in case interview are: Bar/Column chart, Line chart, Percentage chart, Mekko chart, Scatter plot chart, Waterfall chart.

Business knowledge is not a mandatory condition to become a consultant. Nevertheless, it still has specific obligations and advantages for consultants.

There are 9 type of questions that mostly used in actual case interviews. Each type has a different solution, but you can rely on the a 4-step guide to answer

47 case interview examples (from McKinsey, BCG, Bain, etc.)

One of the best ways to prepare for   case interviews  at firms like McKinsey, BCG, or Bain, is by studying case interview examples. 

There are a lot of free sample cases out there, but it's really hard to know where to start. So in this article, we have listed all the best free case examples available, in one place.

The below list of resources includes interactive case interview samples provided by consulting firms, video case interview demonstrations, case books, and materials developed by the team here at IGotAnOffer. Let's continue to the list.

• McKinsey examples
• BCG examples
• Bain examples
• Deloitte examples
• Other firms' examples
• Case books from consulting clubs
• Case interview preparation

Click here to practise 1-on-1 with MBB ex-interviewers

1. mckinsey case interview examples.

• Beautify case interview (McKinsey website)
• Diconsa case interview (McKinsey website)
• Electro-light case interview (McKinsey website)
• GlobaPharm case interview (McKinsey website)
• National Education case interview (McKinsey website)
• Talbot Trucks case interview (McKinsey website)
• Shops Corporation case interview (McKinsey website)
• Conservation Forever case interview (McKinsey website)
• McKinsey case interview guide (by IGotAnOffer)
• Profitability case with ex-McKinsey manager (by IGotAnOffer)
• McKinsey live case interview extract (by IGotAnOffer) - See below

2. BCG case interview examples

• Foods Inc and GenCo case samples  (BCG website)
• Chateau Boomerang written case interview  (BCG website)
• BCG case interview guide (by IGotAnOffer)
• Written cases guide (by IGotAnOffer)
• BCG live case interview with notes (by IGotAnOffer)
• BCG mock case interview with ex-BCG associate director - Public sector case (by IGotAnOffer)
• BCG mock case interview: Revenue problem case (by IGotAnOffer) - See below

3. Bain case interview examples

• CoffeeCo practice case (Bain website)
• FashionCo practice case (Bain website)
• Associate Consultant mock interview video (Bain website)
• Consultant mock interview video (Bain website)
• Written case interview tips (Bain website)
• Bain case interview guide   (by IGotAnOffer)
• Digital transformation case with ex-Bain consultant
• Bain case mock interview with ex-Bain manager (below)

4. Deloitte case interview examples

• Engagement Strategy practice case (Deloitte website)
• Recreation Unlimited practice case (Deloitte website)
• Strategic Vision practice case (Deloitte website)
• Retail Strategy practice case  (Deloitte website)
• Finance Strategy practice case  (Deloitte website)
• Talent Management practice case (Deloitte website)
• Enterprise Resource Management practice case (Deloitte website)
• Footloose written case  (by Deloitte)
• Deloitte case interview guide (by IGotAnOffer)

5. Accenture case interview examples

• Case interview workbook (by Accenture)
• Accenture case interview guide (by IGotAnOffer)

6. OC&C case interview examples

• Leisure Club case example (by OC&C)
• Imported Spirits case example (by OC&C)

7. Oliver Wyman case interview examples

• Wumbleworld case sample (Oliver Wyman website)
• Aqualine case sample (Oliver Wyman website)
• Oliver Wyman case interview guide (by IGotAnOffer)

8. A.T. Kearney case interview examples

• Promotion planning case question (A.T. Kearney website)
• Consulting case book and examples (by A.T. Kearney)
• AT Kearney case interview guide (by IGotAnOffer)

9. Strategy& / PWC case interview examples

• Presentation overview with sample questions (by Strategy& / PWC)
• Strategy& / PWC case interview guide (by IGotAnOffer)

10. L.E.K. Consulting case interview examples

• Case interview example video walkthrough   (L.E.K. website)
• Market sizing case example video walkthrough  (L.E.K. website)

11. Roland Berger case interview examples

• Transit oriented development case webinar part 1  (Roland Berger website)
• Transit oriented development case webinar part 2   (Roland Berger website)
• 3D printed hip implants case webinar part 1   (Roland Berger website)
• 3D printed hip implants case webinar part 2   (Roland Berger website)
• Roland Berger case interview guide   (by IGotAnOffer)

12. Capital One case interview examples

• Case interview example video walkthrough  (Capital One website)
• Capital One case interview guide (by IGotAnOffer)

12. EY Parthenon case interview examples

• Candidate-led case example with feedback (by IGotAnOffer)

14. Consulting clubs case interview examples

• Berkeley case book (2006)
• Columbia case book (2006)
• Darden case book (2012)
• Darden case book (2018)
• Duke case book (2010)
• Duke case book (2014)
• ESADE case book (2011)
• Goizueta case book (2006)
• Illinois case book (2015)
• LBS case book (2006)
• MIT case book (2001)
• Notre Dame case book (2017)
• Ross case book (2010)
• Wharton case book (2010)

Practice with experts

Using case interview examples is a key part of your interview preparation, but it isn’t enough.

At some point you’ll want to practise with friends or family who can give some useful feedback. However, if you really want the best possible preparation for your case interview, you'll also want to work with ex-consultants who have experience running interviews at McKinsey, Bain, BCG, etc.

If you know anyone who fits that description, fantastic! But for most of us, it's tough to find the right connections to make this happen. And it might also be difficult to practice multiple hours with that person unless you know them really well.

Here's the good news. We've already made the connections for you. We’ve created a coaching service where you can do mock case interviews 1-on-1 with ex-interviewers from MBB firms . Start scheduling sessions today!

Related articles:

2024 Guide: 23 Data Science Case Study Interview Questions (with Solutions)

Case studies are often the most challenging aspect of data science interview processes. They are crafted to resemble a company’s existing or previous projects, assessing a candidate’s ability to tackle prompts, convey their insights, and navigate obstacles.

To excel in data science case study interviews, practice is crucial. It will enable you to develop strategies for approaching case studies, asking the right questions to your interviewer, and providing responses that showcase your skills while adhering to time constraints.

The best way of doing this is by using a framework for answering case studies. For example, you could use the product metrics framework and the A/B testing framework to answer most case studies that come up in data science interviews.

There are four main types of data science case studies:

• Product Case Studies - This type of case study tackles a specific product or feature offering, often tied to the interviewing company. Interviewers are generally looking for a sense of business sense geared towards product metrics.
• Data Analytics Case Study Questions - Data analytics case studies ask you to propose possible metrics in order to investigate an analytics problem. Additionally, you must write a SQL query to pull your proposed metrics, and then perform analysis using the data you queried, just as you would do in the role.
• Modeling and Machine Learning Case Studies - Modeling case studies are more varied and focus on assessing your intuition for building models around business problems.
• Business Case Questions - Similar to product questions, business cases tackle issues or opportunities specific to the organization that is interviewing you. Often, candidates must assess the best option for a certain business plan being proposed, and formulate a process for solving the specific problem.

How Case Study Interviews Are Conducted

Oftentimes as an interviewee, you want to know the setting and format in which to expect the above questions to be asked. Unfortunately, this is company-specific: Some prefer real-time settings, where candidates actively work through a prompt after receiving it, while others offer some period of days (say, a week) before settling in for a presentation of your findings.

It is therefore important to have a system for answering these questions that will accommodate all possible formats, such that you are prepared for any set of circumstances (we provide such a framework below).

Why Are Case Study Questions Asked?

Case studies assess your thought process in answering data science questions. Specifically, interviewers want to see that you have the ability to think on your feet, and to work through real-world problems that likely do not have a right or wrong answer. Real-world case studies that are affecting businesses are not binary; there is no black-and-white, yes-or-no answer. This is why it is important that you can demonstrate decisiveness in your investigations, as well as show your capacity to consider impacts and topics from a variety of angles. Once you are in the role, you will be dealing directly with the ambiguity at the heart of decision-making.

Perhaps most importantly, case interviews assess your ability to effectively communicate your conclusions. On the job, data scientists exchange information across teams and divisions, so a significant part of the interviewer’s focus will be on how you process and explain your answer.

Quick tip: Because case questions in data science interviews tend to be product- and company-focused, it is extremely beneficial to research current projects and developments across different divisions , as these initiatives might end up as the case study topic.

How to Answer Data Science Case Study Questions (The Framework)

There are four main steps to tackling case questions in Data Science interviews, regardless of the type: clarify, make assumptions, gather context, and provide data points and analysis.

Step 1: Clarify

Clarifying is used to gather more information . More often than not, these case studies are designed to be confusing and vague. There will be unorganized data intentionally supplemented with extraneous or omitted information, so it is the candidate’s responsibility to dig deeper, filter out bad information, and fill gaps. Interviewers will be observing how an applicant asks questions and reach their solution.

For example, with a product question, you might take into consideration:

• What is the product?
• How does the product work?
• How does the product align with the business itself?

Step 2: Make Assumptions

When you have made sure that you have evaluated and understand the dataset, start investigating and discarding possible hypotheses. Developing insights on the product at this stage complements your ability to glean information from the dataset, and the exploration of your ideas is paramount to forming a successful hypothesis. You should be communicating your hypotheses with the interviewer, such that they can provide clarifying remarks on how the business views the product, and to help you discard unworkable lines of inquiry. If we continue to think about a product question, some important questions to evaluate and draw conclusions from include:

• Who uses the product? Why?
• What are the goals of the product?
• How does the product interact with other services or goods the company offers?

The goal of this is to reduce the scope of the problem at hand, and ask the interviewer questions upfront that allow you to tackle the meat of the problem instead of focusing on less consequential edge cases.

Step 3: Propose a Solution

Now that a hypothesis is formed that has incorporated the dataset and an understanding of the business-related context, it is time to apply that knowledge in forming a solution. Remember, the hypothesis is simply a refined version of the problem that uses the data on hand as its basis to being solved. The solution you create can target this narrow problem, and you can have full faith that it is addressing the core of the case study question.

Keep in mind that there isn’t a single expected solution, and as such, there is a certain freedom here to determine the exact path for investigation.

Step 4: Provide Data Points and Analysis

Finally, providing data points and analysis in support of your solution involves choosing and prioritizing a main metric. As with all prior factors, this step must be tied back to the hypothesis and the main goal of the problem. From that foundation, it is important to trace through and analyze different examples– from the main metric–in order to validate the hypothesis.

Quick tip: Every case question tends to have multiple solutions. Therefore, you should absolutely consider and communicate any potential trade-offs of your chosen method. Be sure you are communicating the pros and cons of your approach.

Note: In some special cases, solutions will also be assessed on the ability to convey information in layman’s terms. Regardless of the structure, applicants should always be prepared to solve through the framework outlined above in order to answer the prompt.

The Role of Effective Communication

There have been multiple articles and discussions conducted by interviewers behind the Data Science Case Study portion, and they all boil down success in case studies to one main factor: effective communication.

All the analysis in the world will not help if interviewees cannot verbally work through and highlight their thought process within the case study. Again, interviewers are keyed at this stage of the hiring process to look for well-developed “soft-skills” and problem-solving capabilities. Demonstrating those traits is key to succeeding in this round.

To this end, the best advice possible would be to practice actively going through example case studies, such as those available in the Interview Query questions bank . Exploring different topics with a friend in an interview-like setting with cold recall (no Googling in between!) will be uncomfortable and awkward, but it will also help reveal weaknesses in fleshing out the investigation.

Don’t worry if the first few times are terrible! Developing a rhythm will help with gaining self-confidence as you become better at assessing and learning through these sessions.

Finding the right data science talent for case studies? OutSearch.ai ’s AI-driven platform streamlines this by pinpointing candidates who excel in real-world scenarios. Discover how they can help you match with top problem-solvers.

Product Case Study Questions

With product data science case questions , the interviewer wants to get an idea of your product sense intuition. Specifically, these questions assess your ability to identify which metrics should be proposed in order to understand a product.

1. How would you measure the success of private stories on Instagram, where only certain close friends can see the story?

Start by answering: What is the goal of the private story feature on Instagram? You can’t evaluate “success” without knowing what the initial objective of the product was, to begin with.

One specific goal of this feature would be to drive engagement. A private story could potentially increase interactions between users, and grow awareness of the feature.

Now, what types of metrics might you propose to assess user engagement? For a high-level overview, we could look at:

• Average stories per user per day
• Average Close Friends stories per user per day

However, we would also want to further bucket our users to see the effect that Close Friends stories have on user engagement. By bucketing users by age, date joined, or another metric, we could see how engagement is affected within certain populations, giving us insight on success that could be lost if looking at the overall population.

2. How would you measure the success of acquiring new users through a 30-day free trial at Netflix?

More context: Netflix is offering a promotion where users can enroll in a 30-day free trial. After 30 days, customers will automatically be charged based on their selected package. How would you measure acquisition success, and what metrics would you propose to measure the success of the free trial?

One way we can frame the concept specifically to this problem is to think about controllable inputs, external drivers, and then the observable output . Start with the major goals of Netflix:

• Acquiring new users to their subscription plan.
• Decreasing churn and increasing retention.

Looking at acquisition output metrics specifically, there are several top-level stats that we can look at, including:

• Conversion rate percentage
• Cost per free trial acquisition
• Daily conversion rate

With these conversion metrics, we would also want to bucket users by cohort. This would help us see the percentage of free users who were acquired, as well as retention by cohort.

3. How would you measure the success of Facebook Groups?

Start by considering the key function of Facebook Groups . You could say that Groups are a way for users to connect with other users through a shared interest or real-life relationship. Therefore, the user’s goal is to experience a sense of community, which will also drive our business goal of increasing user engagement.

What general engagement metrics can we associate with this value? An objective metric like Groups monthly active users would help us see if Facebook Groups user base is increasing or decreasing. Plus, we could monitor metrics like posting, commenting, and sharing rates.

There are other products that Groups impact, however, specifically the Newsfeed. We need to consider Newsfeed quality and examine if updates from Groups clog up the content pipeline and if users prioritize those updates over other Newsfeed items. This evaluation will give us a better sense of if Groups actually contribute to higher engagement levels.

4. How would you analyze the effectiveness of a new LinkedIn chat feature that shows a “green dot” for active users?

Note: Given engineering constraints, the new feature is impossible to A/B test before release. When you approach case study questions, remember always to clarify any vague terms. In this case, “effectiveness” is very vague. To help you define that term, you would want first to consider what the goal is of adding a green dot to LinkedIn chat.

5. How would you diagnose why weekly active users are up 5%, but email notification open rates are down 2%?

What assumptions can you make about the relationship between weekly active users and email open rates? With a case question like this, you would want to first answer that line of inquiry before proceeding.

Hint: Open rate can decrease when its numerator decreases (fewer people open emails) or its denominator increases (more emails are sent overall). Taking these two factors into account, what are some hypotheses we can make about our decrease in the open rate compared to our increase in weekly active users?

6. Let’s say you’re working on Facebook Groups. A product manager decides to add threading to comments on group posts. We see comments per user increase by 10% but posts go down 2%. Why would that be?

To approach this question, consider the impact of threading on user behavior and engagement. Analyze how threading changes the way users interact with posts and comments. Identify relevant metrics such as the number of comments per post, new post frequency, user engagement, and duplicate posts to test your hypotheses about these behavioral changes.

Data Analytics Case Study Questions

Data analytics case studies ask you to dive into analytics problems. Typically these questions ask you to examine metrics trade-offs or investigate changes in metrics. In addition to proposing metrics, you also have to write SQL queries to generate the metrics, which is why they are sometimes referred to as SQL case study questions .

7. Using the provided data, generate some specific recommendations on how DoorDash can improve.

In this DoorDash analytics case study take-home question you are provided with the following dataset:

• Customer order time
• Restaurant order time
• Driver arrives at restaurant time
• Order delivered time
• Customer ID
• Amount of discount
• Amount of tip

With a dataset like this, there are numerous recommendations you can make. A good place to start is by thinking about the DoorDash marketplace, which includes drivers, riders and merchants. How could you analyze the data to increase revenue, driver/user retention and engagement in that marketplace?

8. After implementing a notification change, the total number of unsubscribes increases. Write a SQL query to show how unsubscribes are affecting login rates over time.

This is a Twitter data science interview question , and let’s say you implemented this new feature using an A/B test. You are provided with two tables: events (which includes login, nologin and unsubscribe ) and variants (which includes control or variant ).

We are tasked with comparing multiple different variables at play here. There is the new notification system, along with its effect of creating more unsubscribes. We can also see how login rates compare for unsubscribes for each bucket of the A/B test.

Given that we want to measure two different changes, we know we have to use GROUP BY for the two variables: date and bucket variant. What comes next?

9. Write a query to disprove the hypothesis: Data scientists who switch jobs more often end up getting promoted faster.

More context: You are provided with a table of user experiences representing each person’s past work experiences and timelines.

This question requires a bit of creative problem-solving to understand how we can prove or disprove the hypothesis. The hypothesis is that a data scientist that ends up switching jobs more often gets promoted faster.

Therefore, in analyzing this dataset, we can prove this hypothesis by separating the data scientists into specific segments on how often they jump in their careers.

For example, if we looked at the number of job switches for data scientists that have been in their field for five years, we could prove the hypothesis that the number of data science managers increased as the number of career jumps also rose.

• Never switched jobs: 10% are managers
• Switched jobs once: 20% are managers
• Switched jobs twice: 30% are managers
• Switched jobs three times: 40% are managers

10. Write a SQL query to investigate the hypothesis: Click-through rate is dependent on search result rating.

More context: You are given a table with search results on Facebook, which includes query (search term), position (the search position), and rating (human rating from 1 to 5). Each row represents a single search and includes a column has_clicked that represents whether a user clicked or not.

This question requires us to formulaically do two things: create a metric that can analyze a problem that we face and then actually compute that metric.

Think about the data we want to display to prove or disprove the hypothesis. Our output metric is CTR (clickthrough rate). If CTR is high when search result ratings are high and CTR is low when the search result ratings are low, then our hypothesis is proven. However, if the opposite is true, CTR is low when the search result ratings are high, or there is no proven correlation between the two, then our hypothesis is not proven.

With that structure in mind, we can then look at the results split into different search rating buckets. If we measure the CTR for queries that all have results rated at 1 and then measure CTR for queries that have results rated at lower than 2, etc., we can measure to see if the increase in rating is correlated with an increase in CTR.

11. How would you help a supermarket chain determine which product categories should be prioritized in their inventory restructuring efforts?

You’re working as a Data Scientist in a local grocery chain’s data science team. The business team has decided to allocate store floor space by product category (e.g., electronics, sports and travel, food and beverages). Help the team understand which product categories to prioritize as well as answering questions such as how customer demographics affect sales, and how each city’s sales per product category differs.

Check out our Data Analytics Learning Path .

12. Write a SQL query to select the 2nd highest salary in the engineering department.

Note: If more than one person shares the highest salary, the query should select the next highest salary.

When asked for the “2nd highest” value, focus on getting a singular value. Filter the data to include only relevant entries (e.g., engineering salaries), order the results, and use LIMIT and OFFSET to isolate the value. First, limit to the top two distinct salaries and select the second, or use OFFSET to skip the highest and get the second highest.

Modeling and Machine Learning Case Questions

Machine learning case questions assess your ability to build models to solve business problems. These questions can range from applying machine learning to solve a specific case scenario to assessing the validity of a hypothetical existing model . The modeling case study requires a candidate to evaluate and explain any certain part of the model building process.

13. Describe how you would build a model to predict Uber ETAs after a rider requests a ride.

Common machine learning case study problems like this are designed to explain how you would build a model. Many times this can be scoped down to specific parts of the model building process. Examining the example above, we could break it up into:

How would you evaluate the predictions of an Uber ETA model?

What features would you use to predict the Uber ETA for ride requests?

Our recommended framework breaks down a modeling and machine learning case study to individual steps in order to tackle each one thoroughly. In each full modeling case study, you will want to go over:

• Data processing
• Feature Selection
• Model Selection
• Cross Validation
• Evaluation Metrics
• Testing and Roll Out

14. How would you build a model that sends bank customers a text message when fraudulent transactions are detected?

Additionally, the customer can approve or deny the transaction via text response.

Let’s start out by understanding what kind of model would need to be built. We know that since we are working with fraud, there has to be a case where either a fraudulent transaction is or is not present .

Hint: This problem is a binary classification problem. Given the problem scenario, what considerations do we have to think about when first building this model? What would the bank fraud data look like?

15. How would you design the inputs and outputs for a model that detects potential bombs at a border crossing?

Additional questions. How would you test the model and measure its accuracy? Remember the equation for precision:

Because we can not have high TrueNegatives, recall should be high when assessing the model.

16. Which model would you choose to predict Airbnb booking prices: Linear regression or random forest regression?

Start by answering this question: What are the main differences between linear regression and random forest?

Random forest regression is based on the ensemble machine learning technique of bagging . The two key concepts of random forests are:

• Random sampling of training observations when building trees.
• Random subsets of features for splitting nodes.

Random forest regressions also discretize continuous variables, since they are based on decision trees and can split categorical and continuous variables.

Linear regression, on the other hand, is the standard regression technique in which relationships are modeled using a linear predictor function, the most common example represented as y = Ax + B.

Let’s see how each model is applicable to Airbnb’s bookings. One thing we need to do in the interview is to understand more context around the problem of predicting bookings. To do so, we need to understand which features are present in our dataset.

We can assume the dataset will have features like:

• Location features.
• Seasonality.
• Number of bedrooms and bathrooms.
• Private room, shared, entire home, etc.
• External demand (conferences, festivals, sporting events).

Which model would be the best fit for this feature set?

17. Using a binary classification model that pre-approves candidates for a loan, how would you give each rejected application a rejection reason?

More context: You do not have access to the feature weights. Start by thinking about the problem like this: How would the problem change if we had ten, one thousand, or ten thousand applicants that had gone through the loan qualification program?

Pretend that we have three people: Alice, Bob, and Candace that have all applied for a loan. Simplifying the financial lending loan model, let us assume the only features are the total number of credit cards , the dollar amount of current debt , and credit age . Here is a scenario:

Alice: 10 credit cards, 5 years of credit age, $\$20K$ in debt

Bob: 10 credit cards, 5 years of credit age, $\$15K$ in debt

Candace: 10 credit cards, 5 years of credit age, $\$10K$ in debt

If Candace is approved, we can logically point to the fact that Candace’s $\$10K$ in debt swung the model to approve her for a loan. How did we reason this out?

If the sample size analyzed was instead thousands of people who had the same number of credit cards and credit age with varying levels of debt, we could figure out the model’s average loan acceptance rate for each numerical amount of current debt. Then we could plot these on a graph to model the y-value (average loan acceptance) versus the x-value (dollar amount of current debt). These graphs are called partial dependence plots.

Business Case Questions

In data science interviews, business case study questions task you with addressing problems as they relate to the business. You might be asked about topics like estimation and calculation, as well as applying problem-solving to a larger case. One tip: Be sure to read up on the company’s products and ventures before your interview to expose yourself to possible topics.

18. How would you estimate the average lifetime value of customers at a business that has existed for just over one year?

More context: You know that the product costs $\$100$ per month, averages 10% in monthly churn, and the average customer stays for 3.5 months.

Remember that lifetime value is defined by the prediction of the net revenue attributed to the entire future relationship with all customers averaged. Therefore, $\$100$ * 3.5 = $\$350$… But is it that simple?

Because this company is so new, our average customer length (3.5 months) is biased from the short possible length of time that anyone could have been a customer (one year maximum). How would you then model out LTV knowing the churn rate and product cost?

19. How would you go about removing duplicate product names (e.g. iPhone X vs. Apple iPhone 10) in a massive database?

See the full solution for this Amazon business case question on YouTube:

20. What metrics would you monitor to know if a 50% discount promotion is a good idea for a ride-sharing company?

This question has no correct answer and is rather designed to test your reasoning and communication skills related to product/business cases. First, start by stating your assumptions. What are the goals of this promotion? It is likely that the goal of the discount is to grow revenue and increase retention. A few other assumptions you might make include:

• The promotion will be applied uniformly across all users.
• The 50% discount can only be used for a single ride.

How would we be able to evaluate this pricing strategy? An A/B test between the control group (no discount) and test group (discount) would allow us to evaluate Long-term revenue vs average cost of the promotion. Using these two metrics how could we measure if the promotion is a good idea?

21. A bank wants to create a new partner card, e.g. Whole Foods Chase credit card). How would you determine what the next partner card should be?

More context: Say you have access to all customer spending data. With this question, there are several approaches you can take. As your first step, think about the business reason for credit card partnerships: they help increase acquisition and customer retention.

One of the simplest solutions would be to sum all transactions grouped by merchants. This would identify the merchants who see the highest spending amounts. However, the one issue might be that some merchants have a high-spend value but low volume. How could we counteract this potential pitfall? Is the volume of transactions even an important factor in our credit card business? The more questions you ask, the more may spring to mind.

22. How would you assess the value of keeping a TV show on a streaming platform like Netflix?

Say that Netflix is working on a deal to renew the streaming rights for a show like The Office , which has been on Netflix for one year. Your job is to value the benefit of keeping the show on Netflix.

Start by trying to understand the reasons why Netflix would want to renew the show. Netflix mainly has three goals for what their content should help achieve:

• Acquisition: To increase the number of subscribers.
• Retention: To increase the retention of active subscribers and keep them on as paying members.
• Revenue: To increase overall revenue.

One solution to value the benefit would be to estimate a lower and upper bound to understand the percentage of users that would be affected by The Office being removed. You could then run these percentages against your known acquisition and retention rates.

23. How would you determine which products are to be put on sale?

Let’s say you work at Amazon. It’s nearing Black Friday, and you are tasked with determining which products should be put on sale. You have access to historical pricing and purchasing data from items that have been on sale before. How would you determine what products should go on sale to best maximize profit during Black Friday?

To start with this question, aggregate data from previous years for products that have been on sale during Black Friday or similar events. You can then compare elements such as historical sales volume, inventory levels, and profit margins.

Learn More About Feature Changes

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Case Interview: The Free Preparation Guide (2024)

The case interview is a challenging interview format that simulates the job of a management consultant , testing candidates across a wide range of problem-solving dimensions.

McKinsey, BCG and Bain – along with other top consulting firms – use the case interview because it’s a statistically proven predictor of how well a candidate will perform in the role. The format is not only used by management consulting firms. Other types of organizations – like tech companies, financial services institutions, and non-profits – often use case interviews to assess candidates who are interviewing for roles focused on shaping strategic initiatives.

If you’re preparing to face a case interview, you may be feeling a little apprehensive. The format is notoriously demanding and unlike any other type of recruitment assessment you may have experienced before. However, with the right preparation and investment of time and effort, it is possible to master.

In this guide, we break down everything you need to know about the case interview, outlining exactly what you need to do to prepare effectively and ace the case.

Key takeaways

• The classic case interview format follows the same steps that a management consultant would encounter on a client project. The interview is a little like a role-play where the interviewer plays the role of a client and the candidate plays the part of the consultant hired to solve the problem.
• Some firms occasionally deviate from the classic case interview format. Popular alternatives include written case studies – which require candidates to review paper documents and then prepare and deliver a presentation – and market sizing case interviews, which require candidates to estimate a number.
• Case interviews test candidates against a set of six problem-solving dimensions: structuring, math, judgment and insights, creativity, synthesis, and case leadership. The interviewer uses a scorecard to assess the candidate’s performance in each of these areas.
• Case interview questions can be about almost any type of challenge or opportunity. However, our research indicates that there are 10 types of questions that are asked most frequently at top consulting firms. These include questions on profit improvement, revenue growth, and market entry.
• To do well in a case interview, it’s vital to create custom interview structures that meet the conditions of the ‘AIM’ test. It helps to have a good working knowledge of key case interview frameworks, but this alone is not sufficient.
• A strong grasp of case math is also crucial when it comes to case interview performance. While only high-school level math skills are required, it’s an aspect of the case interview that many candidates find challenging.
• Successful candidates are able to summarize their findings effectively. They also demonstrate strong case leadership by progressing through the case proactively and remaining focused on its overarching objectives.
• To prepare for a case interview, it’s essential to learn every problem-solving skill that will be assessed. We teach all of these skills in our Interview Prep Course , which contains all the video lectures, sample interviews, case material, and practice tools you’ll need to ace any case interview.
• Most candidates who go on to receive an offer from a top consulting firm like McKinsey, BCG or Bain complete at least 25 live practice sessions with a partner before their interview. You’ll find over 100 high-quality cases in our Case Library and a diverse community of candidates available for practice in our Practice Room .
• Some candidates choose to supplement their preparation by working with a coach who has been an interviewer at a top consulting firm. Here at CaseCoach, our coaches have all been handpicked from the alumni of top firms such as McKinsey, BCG and Bain.
• Although the world’s top consulting firms all test candidates using similar methods, none of them approach the interview process in exactly the same way. If you’re preparing to interview at a top consulting firm, it’s important to do your research and find out what you can expect.

An introduction to the case interview

The case interview format, the classic case interview.

The vast majority of case interviews follow the same steps that management consultants encounter on real client projects.

• Brief: The interviewer gives the candidate a brief for the case. They explain the context in which the client is operating, and outline the challenge they’re facing.
• Clarification: The candidate then has the chance to ask clarifying questions. They might do this to ensure they’ve understood the context of the problem correctly or to confirm the client’s goals.
• Reflection: The candidate takes 60 to 90 seconds or so to reflect and lay out a structured approach to solving the case.
• Analysis: The candidate and interviewer then work through the case together, carrying out analyses and moving toward a recommendation. This is the part of the case where you’ll be handling numerical questions, reviewing exhibits, coming up with creative ideas, and so on. It comprises the vast majority of the time you’ll spend on the case.
• Synthesis: The case concludes with the candidate synthesizing their findings and making an overall recommendation to the client.

So what does this unique interview format look and feel like? In reality, a consulting case interview is a little like a role-play. The interviewer plays the role of a manager or client, and the candidate plays the part of the consultant hired to solve the problem. However, a case interview shouldn’t feel like a performance. The most successful candidates treat it as a natural conversation between two professional people.

In the video below you can see an example of exceptional case interview performance in action. The candidate and interviewer in the video are both former McKinsey interviewers.

Interviewer-led vs candidate-led cases

Although the classic case interview has an established format and assesses a specific set of skills, cases can be delivered in different ways. Some are more candidate-led, while others are more interviewer-led

In a candidate-led case, the candidate is in the driver’s seat and is free to explore different aspects of the problem. Interviewers don’t tell candidates what to focus on next. Instead, they provide additional information – like an exhibit or a new fact – when asked. The candidate then analyzes the information and suggests next steps to get to the answer.

In an interviewer-led case, the interviewer may interrupt the candidate and ask them to either perform a specific investigation or focus on a different aspect of the problem. This doesn’t mean the interview is going badly; the interviewer is simply following a script. As a result, in an interviewer-led case, candidates are less likely to take the wrong path.

It’s difficult to predict which style of case you’ll receive. Some firms are known for using one style of interview more frequently than another. However, in practice, most interviews fall somewhere between the two extremes, depending on the style of the interviewer and the case material they’re using. You should therefore always be ready to suggest next steps and have a view about how to get to the answer.

Other case interview formats

While the classic case interview is most common, there are a couple of other interview formats that top consulting firms use from time to time:

The written case study

Some management consulting firms use written case studies to simulate the experience of carrying out consulting work even more accurately than the classic, verbal case interview. In some locations, BCG and Bain have been known to adopt this approach for a small minority of candidates.

In written cases, candidates review a series of paper documents and then structure the problem, run some numbers, generate ideas and, finally, deliver a short presentation. You can learn more in our article on how to crack written case studies .

Market sizing case interviews

Management consulting firms and other employers sometimes use market sizing questions – also known as estimation questions – as a standalone interview format to assess candidates on a wide range of problem-solving dimensions.

In a market sizing interview, you’ll be asked to estimate a number. This might be something like the revenue of a sandwich store or how many ATMs there are in a certain city. The ability to size a market is also a skill required for solving many case interview questions. You can learn more in our article on how to nail market sizing case interviews .

Some key differences to expect

While case interviews are highly codified, it’s important to remember that every interview is unique.

In the final round of interviews, for example, cases may feel less scripted than they did in the first stage. Partners – who are part of the interviewing group in the final round – often use the same case for years at a time. This means they can deliver it without a script and, as a result, tend to give candidates more room to take the lead. You can learn more in our article on the differences between a first and final-round interview at McKinsey, BCG and Bain .

In addition, each firm or office might bring their own nuance or style to the classic case interview format. It’s important to do your research and find out what you can expect from the interview experience at your target firm or office. You can learn more in our article on how the interviews at McKinsey, BCG and Bain differ .

The skills assessed in case interviews

Case interviews are primarily about testing a set of problem-solving skills. The interviewer uses a scorecard to assess a candidate’s performance in the following dimensions:

• Structuring: This is the ability to break problems down into logical drivers. It’s most obviously required at the beginning of a case, where you can pause and take a moment to come up with an approach. But it’s also tested each time you have to consider a new aspect of the problem.
• Math: Most cases contain a quantitative component, such as estimation questions, break-even questions, or other calculations. To do well in this dimension, you need to lay out a clear and efficient approach, run calculations quickly and accurately, and then state their implications for the case.
• Judgment and insights: This dimension is about extracting insights from data, usually by interpreting information in a chart. Performing well in this area involves processing new information quickly, prioritizing what’s important, and connecting your findings to develop sound recommendations.
• Creativity: Cases often have a creative thinking component. Sharing numerous, varied and sound ideas – ideally in a structured way – can help you succeed here.
• Synthesis: This is all about wrapping up the case with a clear and practical recommendation, and delivering it convincingly.
• Case leadership: This dimension is about progressing through the case efficiently and staying focused on its objectives. Case leadership involves gathering facts effectively and building on new findings to develop a recommendation. It’s a particularly important dimension in candidate-led cases.

Questions to expect

If you’re preparing to interview at a top management consulting firm like McKinsey, BCG or Bain, you’re probably curious about the kind of case interview questions you can expect to receive.

To identify the most common case interview questions , we surveyed CaseCoach users who interviewed at either McKinsey, BCG or Bain for a generalist role in 2023. We found that of the 260+ case interviews reported by respondents:

• 20% focused on profit improvement
• 15% focused on revenue growth
• 12% focused on market entry
• 10% focused on cost cutting
• 9% focused on process optimization

These topics align with the typical challenges and opportunities faced by CEOs. Because the job of a management consultant is to help CEOs find solutions to these problems, it’s vital for candidates to demonstrate that they understand the issues behind these questions.

However, while there are some recurring topics, the context and nuances of each individual case mean that no two case questions are the same. Increasingly, firms are testing candidates on questions that fall outside of these recurring topics. One way they’re doing this is by focusing on non-traditional areas, like the public sector. If you’re interviewing for a generalist management consulting role, it’s therefore important to be ready for almost any type of case question.

If you’re interviewing for a role that’s focused on a specific industry or function, like financial services , you’ll likely be given a case focused on that particular area.

How to ace the case

Case interviews require you to think on your feet to solve a complex problem that you’ve never seen before, while being assessed against a number of problem-solving dimensions. Here’s what you need to do to rise to the challenge and ace the case:

1. Create case interview structures that meet the AIM test

Of all the case interview assessment dimensions, structuring is perhaps the most challenging, particularly for those who are just starting out. It requires candidates to propose a prioritized and insightful approach to the case that’s composed of a comprehensive set of independent drivers. Structuring plays a foundational role in the interview, setting the course for the entire conversation.

So, what does good case structuring look like? An effective structure should meet the conditions of the ‘AIM’ test. ‘AIM’ stands for:

• Answer-focused: The structure should identify the client’s goal and the question to solve. It should also provide an approach to answering that question.
• Insightful: The structure should be tailored to the specifics of the client or to the problem in question. You shouldn’t be able to apply it to another case of the same type.
• MECE: This is a well-known acronym among consultants. It stands for ‘mutually exclusive and collectively exhaustive’. In plain English, if a structure is ‘MECE’ it has been broken down into an exhaustive set of independent drivers.

2. Know key case interview frameworks

In a case interview, you’ll be asked to structure a variety of problems. There are a number of frameworks that can help you do this, whether the problem you’re structuring corresponds to a common case question or a different topic entirely:

Business frameworks

You can use established business frameworks to craft custom structures for the most common types of case questions. These include frameworks for mastering profitability questions , answering revenue growth questions and nailing market sizing questions .

Academic frameworks

For unusual case questions that don’t relate to an obvious business framework, it can be helpful to draw on an academic framework like supply and demand, ‘the three Cs’, or Porter’s Five Forces. You can learn more about all of these in our ultimate guide to case interview frameworks . The article includes other business and academic frameworks that you can use to craft custom structures for case questions.

Logical frameworks

Finally, logical frameworks can help you look at the big picture in order to structure your approach. These options can be particularly useful when you’re faced with an unusual case question that doesn’t lend itself to a business or academic framework. Some examples of logical frameworks include:

• Structuring with equations: This approach is most helpful for quantitative case questions. Listen out for introductions that focus on a number. These cases can often be broken down into an equation and then structured along its variables.
• Structuring based on hypotheses: This approach is most helpful for structuring qualitative cases. It involves laying out what you most need to believe in order to validate a specific recommendation. These beliefs form your set of key hypotheses, which you then test as you progress through the case.
• Structuring with root causes: This approach works well for structuring cases that require identifying the reasons for a problem. It involves laying out its potential causes in a way that is mutually exclusive and collectively exhaustive (i.e. MECE).

How to apply these frameworks

While business, academic, and logical frameworks can be helpful when it comes to structuring a problem, learning how to use them correctly is a skill in itself. Simply applying a framework to a case interview question in a ‘cookie-cutter’ fashion is not enough. To impress your interviewer and pass the AIM test, your structure will need to be heavily tailored to the situation at hand. In fact, many case questions can be best answered by combining different frameworks.

Ultimately, interviewers want to understand how your mind works and see you think on your feet. You’ll therefore need to demonstrate that you can propose a custom case interview structure to any question.

3. Be comfortable with simple math

Management consulting firms expect you to navigate mathematical problems confidently and reliably in case interviews. Regardless of your academic background or past experience, you’ll need to be able to set an approach to solve the problem, perform calculations quickly and accurately, and state the implications of your solution.

The good news is that you’ll only be required to demonstrate a high-school level of math skills in case interviews. However, with no calculators allowed and an interviewer looking over your shoulder, it’s natural to find this aspect of the experience a little intimidating.

So, what can you expect from case math? The problems you’ll be asked to solve may take the form of straight calculations, exhibits that require calculations, word problems, and estimation questions.

To do well in this part of the case interview, you’ll need to have a strong understanding of:

• The four operations: addition, subtraction, multiplication, and division
• Key math concepts such as fractions, percentages, and weighted averages
• Business math concepts such as income statements, investments, and valuations

To stand out to your interviewer, you’ll also need to work through math problems confidently and efficiently. Here are our top tips for doing this:

• Keep track of zeros: Case questions often involve large numbers, sometimes in the millions or even billions. Keeping close track of your zeros is therefore crucial. We recommend either counting the zeros in your calculation, using scientific notation, or assigning letter units to zeros.
• Simplify your calculations: This will help you work through problems quickly and efficiently while reducing the potential for mistakes. One way of simplifying calculations is by rounding numbers up or down to make them more ‘friendly’.
• Memorize frequently-used fractions: Some fraction values are used so frequently in case math that knowing them – along with their percentage value and decimal conversions – can save you significant time. We recommend memorizing the fraction and corresponding percentage and decimal values of 1/2, 1/3, all the way through to 1/10.

You can learn more in our guide to mastering case interview math .

4. Summarize your findings

Synthesis is a key skill assessed by interviewers, predominantly at the end of a case interview. You need to provide a clear and sound recommendation that answers the overall question convincingly. You must also describe the key supporting points that informed your recommendation and then outline any further steps you would advise the client to take.

When it comes to concluding cases effectively, this four-step framework can be extremely helpful:

• Quickly play the case question back to your interviewer.
• Answer the question directly and briefly by distilling your response into a single sentence, if possible.
• List the points that support your conclusion.
• Outline the next steps that you recommend to the client.

You can learn more in our article on how to conclude a case study interview .

5. Bring it all together with strong case leadership

Case leadership, more than any other dimension, will give your interviewer an indication of how independently you could handle your workstream as a consultant. It’s a particularly important skill in candidate-led cases, where you’ll set the course of the discussion without the interviewer steering you in a particular direction.

Demonstrating strong case leadership means progressing the case efficiently and staying focused on its overarching objectives. Using a ‘tracker page’ to capture your structure and organize your notes throughout the case will help you in this regard.

Another aspect of case leadership is gathering facts effectively. This includes making reasonable assumptions, requesting missing information, and asking probing questions.

Finally, you’ll be expected to build on new findings to develop your recommendation, adapt your approach, and suggest next steps.

Effective case leadership is all about showing your interviewer that you have a strong command of the problem-solving process. After investigating each key driver in your structure, you need to be able to articulate where you are in your overall approach to solving the problem, and what the next steps should be.

To do this, we recommend using a five-step process to handle every kind of analysis you conduct during the case, whether you’re responding to a numerical question, the data in an exhibit, or something else.

Here’s what that five-step process looks like:

• Set your approach. Define what you’re going to do upfront. It’s particularly important to be explicit here, especially if the analysis is in any way complex or ambiguous.
• Conduct your analysis. Your approach here will vary according to the kind of question you’re working through.
• State your findings. You may also want to make a note of your findings on your tracker page.
• State the implications of your findings. Explain how they impact both your answer to the question and the client’s broader goal.
• Suggest next steps. Your findings will sometimes change how you want to approach the rest of the case. This may mean altering your initial structure and editing it on your tracker page.

6. Be your best on the day

When the day of your interview comes around, you’ll want to be at your very best. But what exactly does this mean?

First, you should present yourself in a professional manner. It goes without saying that you should arrive on time but, ideally, you should plan to arrive early. You should also come equipped with the right material: a pen, squared A4 or letter-size paper pad, and copies of your resume. It’s also vital to dress appropriately for the occasion. Usually, this means wearing formal business dress, but this means different attires in different locations. We recommend doing some research to find out what consultants wear at your target firm and office.

To be at your best on the day of your interview, you must be well rested. Sadly, tiredness is one of the most common reasons for underperformance in consulting interviews. The day before is not the time to cram in further preparation. Instead, aim to have a quiet day and to get plenty of sleep at night.

Ultimately, consulting firms want to hire people who can represent the firm and interact with clients at every level, from the shop floor to the C-suite. Successful candidates treat the case interview as an opportunity to play the role of a management consultant advising a client (i.e. the interviewer). This means exhibiting a great deal of confidence and credibility, together with effective communication and an engaging attitude. It’s vital to stay focused on the overall problem and to drive the resolution of the case while being receptive to the interviewer’s input.

There are a lot of balls to juggle in a case interview, with the added pressure of a potentially life-changing outcome, but successful candidates don’t let their nerves get the better of them. We’ve provided some helpful hints and tips in our article on handling the stress of consulting interviews .

Being your best on the day of your interview requires extensive preparation. It means mastering each dimension of the case interview scorecard to the extent that the skills become second nature to you. It also means completing sufficient case practice to be able to focus on the big picture of the case you’re solving, rather than on simply demonstrating a set of skills.

How to prepare for case interview success

Delivering a standard of performance worthy of an offer from a top firm requires extensive case interview prep. In our experience, most successful candidates invest around 60 hours – or 10 hours each week over a six-week period – in their preparation. Failing to put this effort in is among the most common reasons why many candidates are unsuccessful.

Here’s what effective case interview preparation involves:

Learning the skills

In a case interview, your performance is assessed against a set of common problem-solving dimensions. To recap, these are structuring, math, judgment and insights, creativity, synthesis, and case leadership. It’s important to:

• gain a precise understanding of the expectations on each of these skills
• learn the techniques that will allow you to meet these expectations
• practice until your performance meets the required standard

We teach all these skills in our Interview Prep Course . In our bite-sized video lectures, we map out each of the key skills assessed in a case, and explain what you need to know to demonstrate each skill. We also share our tips on how to improve in each dimension, going above and beyond the advice we’ve included in this article.

In addition, our Interview Prep Course includes many more sample interviews that show real candidates – who went on to join top consulting firms – solving cases. Former consulting interviewers explain what the candidates did well on each dimension and where they could have improved.

Math is a critical prerequisite to handling cases and is something you should be comfortable with before you begin practicing. Our Case Math Course – provided as part of the Interview Prep Course – will help you brush up your skills. It contains 21 video lectures that cover everything you need to know, including the four operations, key math concepts, our pro tips, and business math.

After watching all our Interview Prep and Case Math video lectures, we recommend heading to the ‘Drills’ area of CaseCoach, where you can start practicing specific skills. Drills are interactive exercises that pose rapid-fire questions and provide instant feedback. They help you build your skills and confidence in specific case dimensions quickly, allowing you to make the most of your live case practice with partners. Our Interview Prep Course includes a comprehensive set of drills in four key areas: structuring, calculation, case math and chart interpretation.

When it comes to succeeding in a case interview, nothing beats live practice with a partner. Most candidates who go on to receive an offer from a top consulting firm like McKinsey, BCG or Bain complete at least 25 live practice sessions before their interview.

To practice live cases with a partner, you’ll need access to both case material and practice partners. In our Case Library , you’ll find over 100 cases – complete with solutions – developed by former management consultants. You can download eight of these cases right away by creating a free CaseCoach account. You’ll find a diverse community of fellow candidates who are all available for case interview practice in our Practice Room , where we facilitate over 3,000 practice sessions a week.

You can learn more in our article on how to practice case interviews .

Working with a coach

Some candidates choose to supplement their preparations by working with a consulting interview coach who has been an interviewer at a top firm.

These coaches have the skills and experience to gauge your level of performance and help you identify your areas of strength and weakness. They can also provide you with accurate and helpful feedback on your case-solving skills. This insight can help you accelerate your preparation and improve your performance. Getting used to interviewing with a professional should also help to reduce the stress of the consulting interview experience.

Here at CaseCoach, our coaches are all former consultants and interviewers who have been handpicked from the alumni of top firms such as McKinsey, BCG and Bain.

Do your research

Although employers who use case interviews all test candidates using similar methods, none of them approach the interview process in exactly the same way.

For instance, if you expect to interview with McKinsey, Bain or BCG, it’s helpful to know that these firms all give cases of similar complexity. However, there are some key differences. For example:

• Bain has been known to use estimation questions, such as market sizing, in interviews for its most junior (i.e. Associate Consultant level) roles.
• BCG and Bain occasionally use written cases.
• When it comes to the ‘fit’ interview, McKinsey uses its Personal Experience Interview format, while most Bain offices now use a ‘behavioral interview’ . Only BCG consistently uses the classic fit interview format .

Other differences include the number of rounds of interviews each firm conducts, and their preference for using interviewer-led or candidate-led cases. Wherever you interview, it’s vital to do your research and find out what you might be able to expect.

When it comes to getting ready for the case interview, knowing what you will be assessed on, learning how to succeed, and having access to the best practice resources can all go a long way. Now, you need to put in the hard work and prepare! Good luck.

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Case Interview Preparation

Perform at your best during your case interview., bcgers share their case study interview tips., follow these dos and don ’ ts to ace your case prep:, test your case interview skills with these interactive quizzes., set out a climate strategy for a client., restore client satisfaction at a digital bank., test your it strategy and architecture skills..

Data Preparation for Analytics Using SAS by Gerhard Svolba

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Case Studies

Chapter 25   Case Study 1—Building a Customer Data Mart

Chapter 26   Case Study 2—Deriving Customer Segmentation Measures from Transactional Data

Chapter 27   Case Study 3—Preparing Data for Time Series Analysis

Chapter 28   Case Study 4—Preparing Data in SAS Enterprise Miner

Introduction

In this part we will cover four case studies for data preparation. These case studies refer to the content we presented in earlier chapters and put together in the context of a concrete question. In the case studies we will show example data and complete SAS code to create from the input data the respective output data mart. The following case studies will be examined:

•  building a customer data mart

•  deriving customer segmentation ...

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Management Consulting Case Library

In our Case Library, you will find 200+ case studies for your case interview preparation. Solve challenging problems around market sizing, pricing, or sustainability.

What to Expect in our Case Library

This Is What Our Community Says

Any Open Questions Left? Check Out Our FAQ

Almost all resources on PrepLounge (that includes the case studies) can be used with freemium access which means that you get to try it to a certain degree but have to upgrade to Premium to use it to the full extent. However, you have free and unlimited access to the cases included in the free Basic Membership.

Our selection of case studies mirrors the wide variety of real case interviews . Thus, you can solve challenging problems around market sizing, market entry, pricing, or operations strategy. Moreover, all provided cases are marked with a level of difficulty and the respective case style. This will allow you to filter for interviewer-led (as used by McKinsey) and candidate-led cases. In addition, some of our corporate partners granted some great original cases that have been used in real interviews.

There is no set number of cases you should solve before your interview. However, you will find that the more practice you get and the more different scenarios you tackle, the more confident you will become in dealing with case prompts. Also, in addition to self-study, we recommend that you act out real interview situations. Just choose from over 370,000 candidates and practice cases from the case library together.

Next to each case you will find a button that allows you to post a question directly to the case in our Consulting Forum . Our experts will answer you as soon as possible and support you with your problem. You can also contact the experts directly. 

Are you excited to start practicing for your case interview with real case studies?

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Data Preparation for Regression – Pricing Case Study Example (Part 2)

In the last post we had started a case study example for regression analysis to help an investment firm make money through property price arbitrage (read part 1 :  regression case study example ). This is an interactive case study example and required your help to move forward. These are some of your observations from exploratory analysis that you shared in the comments of the last part ( download the data here )

Katya Chomakova : The house prices are approximately normally distributed. All values except the three outliers lie between 1492000 and 10515000. Among all numeric variables, house prices are most highly correlated with Carpet (0.9) and Builtup(0.75). Mani : Initially, it appears as if housing price has good correlation with built up and carpet. But, once we remove all observations having missing values (which is just ~4% of total obs), I find that the correlation drops down very low (~0.09 range)

Data Preparation for Regression Analysis – by Roopam

Katya and Mani noticed something unusual about missing observations and outliers in the data, and how their presence and absence were changing the results dramatically. This is the reason data preparation is an important exercise for any machine learning or statistical analysis to get consistent results. We will learn about data preparation for regression analysis in this part of the case study. Before we explore this in detail, let’s take a slight detour to understand the crux of stability and talk about fall of heroes.

Every kid needs a hero. I had many when I was growing up. This is a story of how I used a concept in physics caller ‘ center of gravity ‘ to chose one of my heroes by having an imaginary competition between:

Mike Tyson Vs. Bop Bag

The Champion : Mike Tyson was the undisputed heavyweight boxing champion in the late 1980s. He was no Mohammad Ali but was on his path to come closest to  The Greatest . This is where things went wrong for Tyson; he was convicted of rape and was in prison for 3 years. Out of jail and desperate to regain his glory days, Tyson challenged Evander Holyfield,the then undisputed champion. What followed was a disgrace for any sport where during the challenge match Tyson bit a part of Holyfield’s ear off and got disqualified.

The Challenger : Most of us have played with a bop bag or the punching toy as kids. It is designed in such a way that when punched, it topples for a while but eventually stands back up on its own. Bop bag is a perfect example where the center of gravity of the object is highly grounded and stays within its body. You could punch it, kick it, or perturb it in any possible way but the bop bag will stand back up after a fall – yes, it has that cute, funny smile too. On the other hand, like Mike Tyson, most of us struggle big time after a fall. Possibly because our center of gravity is outside our body in other people’s opinion about us. Tyson was mostly driven by the praises from others after a win rather than his love for the game.

The Winner : Center of gravity helped me choose my hero : bop bag. This cute toy reminds me every day to keep my center grounded and inside my body and not let others perturb my core – even when punched. I wish I could always wear a sincere smile like my hero.

Bop bag also has important lessons for data preparation for machine learning and data science models. The data for modeling needs to display stability similar to bop bag and must not give completely different results with different observations. Katya and Mani have noticed a major instability in our data in their exploratory analysis. They have highlighted the presence of missing data and outliers; we will explore these ideas further in this part when we will explore data preparation for regression analysis. Now, let’s go back to our case study example.

Data Preparation for Regression – Case Study Example

In your effort to create a price estimation model, you have gathered this data . The next step is data preparation for regression analysis before the development of a model. This will require us to prepare a robust and logically correct data for analysis.

We will do our analysis for this case study example on R. For this I recommend you install R & R Studio on your system. However, you could also try these codes on this online R engine :  R-Fiddle .

We will first import the data in R and then prepare a summary report for all the variables using this command:

A version of the summary report is displayed here. Remember there are total 932 observations is this data set.

Look at the last row where all the above variables have some missing data. Parking and City_Category are categorical variables hence we have got levels for them. Notice there is missing data in Parking as well marked as ‘Not Provided’.

The first thing we will do is to remove missing variables from this dataset. We will explore later whether removal of missing variables is a good strategy or not. We will also calculate how many observations we will lose by removing missing data.

We have lost 34 observations after removal of missing data. The data set is now down to 898 observations. This is ~4% observations as Mani pointed in his comment. Also, notice that missing variables for categorical variables (Parking) are not removed, could you reason why?

In the next step, we will plot a box plot of housing price to identify outliers for the dependent variable.

Let’s try to look at this extreme outlier by fetching this observation.

This observation seems to be for a large mansion in some countryside. As can be seen in data when compared with the summary data for other observations.

There is no point in keeping this super-rich property in data while preparing a model for middle-class housing. Hence we will remove this observation. The next step is to look at the box plot of all the numerical variables in the model to find unusual observations. We will normalize the data to bring it to the same scale.

Sign-off Note

In this part, we have primarily spent our time on univariate analysis for data preparation for regression. In the next part, we will explore patterns through bivariate analysis before the development of multivariate models. These are some of the questions you may want to ponder and share your view before the next part:

1) We had removed 34 observations with missing data, what impact the removal of missing data can have on our analysis? Could we do something to minimize this impact?

2) Why did we not remove missing values from the categorical variable i.e. Parking?

3) What impact could the extreme outlier, a large mansion, have on the model we are developing for middle-class house prices? Was it a good idea to remove that outlier?

9 thoughts on “ Data Preparation for Regression – Pricing Case Study Example (Part 2) ”

In my opinion it is not always a good idea to exclude missing values from our data for several reasons: 1. We can lose a great amount of data, which is not our case here but is still an issue.Losing data is considered an issue because the amount of data that we use for modeling is crucial for the statistical significance of our results. 2. Sometimes the fact that a value is missing carries a message. For example, missing value for Dist_Hospital could mean that there is no hospital nearby. The same is true for Dist_Taxi and so on. When this is the case, we can impute values to missing data that represent the underlying reason for the data to be missing. For example, missing values for Dist_Hospital might be replaced with a huge number meaning that there is no hospital in the near distance. 3. When we can’t consider the reason behind missing values but we still don’t want to exclude them, a reasonable approach is to impute to missing values the average value for the corresponding variable. According to outliers, we should first examine if they are also high leverage points. If this is the case these observations have a potential to exert an influence to our model and it is recommended to exclude them. If they are not high leverage points, whether to exclude them depends on the modeling technique we would like to use. Decision trees are more sensitive to outliers than regression models. I am looking forward to your next post on the topic.

I do agree with Katya. Here is my opinion about 1.missing values and 2.outliers:

1. Missing values can cause serious problems. Most statistical procedures automatically eliminate cases with missing values, so you may not have enough data to perform the statistical analysis. Alternatively, although the analysis might run, the results may not be statistically significant because of the small amount of input data. Missing values can also cause misleading results by introducing bias.

2. Values may not be identically distributed because of the presence of outliers. Outliers are inconsistent values in the data. Outliers may have a strong influence over the fitted slope and intercept, giving a poor fit to the bulk of the data points. Outliers tend to increase the estimate of residual variance, lowering the chance of rejecting the null hypothesis.

Below is my opinion on the three points:-

1) Instead of removing the missing Data, can’t we substitue some value like taking avg of other observations of that column,etc. I am suggesting this because we might lose some important information by directly removing the missiong value observations.

2) flats having no parking availability can leads to useful information like a middle class family does not require parking space and they may buy flat with no parking facility. I am not quite so sure about this point. Kindly correct me if i am wrong.

3) outliers can lead to our observation in wrong side. But sometimes it is useful to identify some hidden patterns in our data. In our case, this extreme outlier can do a bad impact in our analysis as we are more focused for middle class house prices. so in my opinion, its a good idea to remove it.

Reply – Missing data can bias the model especially when we have Missing values at random and missing values not at random. We can use little test to confirm if the Missing is completely at random. If yes, we can go ahead with the list wise deletion. If it is missing at random we can use multiple imputation methods to use other variables to impute the values and build models on the complete data sets.

Reply – This extreme outlier can highly influence the model parameters. Checking Cook distance and h(leverage of an observation) indicates the observation is a high leverage and point and, therefore, we should remove it before training our model.

If i am not wrong, scale fn works like (x-mean)/sd , so when do we use this scaling process and when do we use log transformation for normalization ? is there any rule ?

Scaling and log transformation have completely different purposes and they cannot be used interchangeably. One of the usage of Scale is in cluster analysis (Read this article) where you are trying to bring different variables on the same scale. On the other hand, log transform is used to make a screwed distribution normal e.g. ARIMA and time series models

Thanks 🙂 it’s a great help 🙂

boxplot(scale(data_without_missing[data_without_missing$House_Price<10^8,c(2:6,9:10)]),col="Orange")

Throwing this error Error in `[.data.frame`(data_without_missing, data_without_missing$House_Price < : undefined columns selected

boxplot(scale(data_without_missing[data_without_missing$House_Price<10^8,c(2:6,9:10)]),col="Orange") need python code

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• Geoffrey R. Weller Library

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• Subject Guides

Knowledge Synthesis Guide

• Data Extraction
• What is Knowledge Synthesis?
• Developing your question
• Consider Eligibility Criteria
• Grey Literature
• Create Search Terms for Each Concept
• Identify Controlled Vocabulary for Each Concept
• Building Your Search
• Translating a Search Strategy
• Run Your Searches
• Reporting Your Results with PRISMA
• Utilize a Screening Tool
• Critical Appraisal
• Information About Publishing This link opens in a new window

Once you have selected the relevant studies to be included in your synthesis, a standardized data extraction form will help you obtain all relevant information from each paper so that you can examine and compare results.

As with both levels of the screening process, it is best practice to have two reviewers complete the data extraction form independently for each study, and to have a plan for resolving disagreement. 

Data Extraction Templete

In the data extraction phase your team should be using a standardized form tailored to your research question and review type. This step can be completed in any number of ways. 

What data do you need to collect?

The data that is relevant to the review will be different for every review. Some categories of data that might be included:

• Identification features (such as article title, author, citation, record number, type of publication, publication date, funding sources)
• Participant characteristics
• Intervention and Setting
• Outcome/Results
• Study quality factors

How to collect the data?

Pre-specifying categories for form fields can help streamline the extraction process, and is especially useful when you plan on performing a quantitative analysis. When doing so, be sure to include, "other," "not reported," or "unclear" options. However, this is not appropriate for all review types and all data fields. 

For example, in the case of integrative, scoping, or qualitative systematic reviews, it may make more sense to have open data fields for outcomes. 

What to use to collect the data?

• Systematic review software (Distiller, Covidence, PICO Portal)
• Spreadsheet (Excel, Google Sheets)
• Survey Tool (Microsoft Forms, Survey Monkey)

Examples of Data Extraction

• Evidence Synthesis for Determining the Responsiveness of Depression Questionnaires and Optimal Treatment Duration for Antidepressant Medication Evidence Table 2 - Williams, J.W., Slubicki, M.N., & Tweedy, D.S., Bradford, D.W., Trivedi, R.B., & Baker, D. (2009). Evidence Synthesis for Determining the Responsiveness of Depression Questionnaires and Optimal Treatment Duration for Antidepressant Medication [Internet]. Washington, DC: Department of Veterans Affairs (US).
• Methods for the development of NICE public health guidance (third edition) Includes example for both quantitative and qualitative tables - National Institute for Health and Care Excellence. (2012). Methods for the development of NICE public health guidance (third edition): Appendix K examples of evidence tables.
• Evidence-based practice step by step. Critical appraisal of the evidence: part I: An introduction to gathering, evaluating, and recording the evidence Data extraction table in article - Fineout-Overholt E, Melnyk BM, Stillwell SB, & Williamson KM. (2010). Evidence-based practice step by step. Critical appraisal of the evidence: part I: An introduction to gathering, evaluating, and recording the evidence...fifth in a series. AJN American Journal of Nursing, 110(7), 47–52.
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AI: From exploration to production – five case studies on GenAI in action

Many organisations are testing out uses for generative ai, but how are they getting on we speak to five early adopters to find out the lessons learned so far.

• Mark Samuels

The launch of ChatGPT from OpenAI in late 2022 thrust years of underground research on artificial intelligence (AI) into the limelight. Two years after the first publicly available generative AI (GenAI) tools surfaced, the excitement about this emerging technology shows no sign of abating, particularly in blue-chip boardrooms.

The rate at which companies deploy GenAI programmes doubled between December 2023 and July 2024, according to Bloomberg Intelligence . Its survey shows AI and machine learning are still top of mind for CIOs and their C-suite peers, with companies investing in foundational models, GPUs and supporting cloud services.

However, other research suggests turning excitement for AI into something useful is much harder. Companies struggle to move GenAI projects into production, according to Deloitte . The consulting giant says 70% of business leaders have moved 30% or fewer of their AI experiments into production.

Worse still, analyst Gartner has predicted that 30% of GenAI projects will be abandoned after the proof-of-concept stage by the end of 2025. So, why are organisations struggling to make the most of AI? We spoke to five business leaders at the recent Snowflake Summit 2024 in San Francisco to ask how executives can turn AI into a competitive advantage.

TUI: Get some great principles

Anastasiia Stefanska, data analyst for analytics and AI at TUI, is helping her organisation exploit emerging technology. The holiday firm uses Snowflake to create a platform for data-led change.

“I would say we’re full speed ahead on using AI,” says Stefanska. “We believe we can achieve a lot. We have worked in the last few quarters on identifying use cases. Some of these cases are in production, and other high-potential use cases are being worked on.”

Stefanska’s colleague, Bastian Handke, technology team lead for the enterprise datawarehouse platform at TUI, says the company uses generative AI for data analysis. The company also uses chatbots in training programmes. These bots speed up the onboarding process for new staff. TUI also uses Cortex AI, Snowflake’s large language model (LLM).

“There are many use cases,” says Handke. “We do sentiment analysis using the functions from Cortex, like translate. Our colleagues in other countries get answers from their customers in different languages. To analyse that data with functions in Cortex is super useful.”

Stefanska says TUI has created official documentation to guide its AI explorations. These papers incorporate two principles. First, there is a focus on enablement – the company wants employees to feel comfortable to suggest use cases. The second principle ensures humans stay in the loop.

“The decision is with the human,” she says. “The governance of the models and the executions are embedded into how we do things. At TUI, we understand that the chatbots are machines. We treat them with respect due to their accumulated knowledge, but we also lay a human eye on their processes.”

Hastings Direct: Find the right areas to explore

Sasha Jory, CIO at insurer Hastings Direct , says her firm uses AI in several areas, including underwriting and dealing with customer queries. She says the key to success is ensuring your data is managed and understandable.

“AI loves data,” she says. “You’ve got to get everything in a format AI can read, digest and use. For example, you’ve got to turn recordings into text so that AI can read the data and give answers. Ensuring collaboration between our machine learning, our AI and our data, in the right place and format, is critical for success.”

Jory says Hastings uses Azure-powered machine learning in underwriting. The technology has helped the company refine its pricing and risk models. “The technology is in production and doing very well,” she says.

“We have seen an improvement in speed to market by more than 100%, the number of underwriting changes we are now able to make has more than trebled, and the route to go-live is fully automated straight-through processing, making releases intraday and simple to execute.”

“We’re not biting on the hype. We don’t think AI is the panacea for everything. AI must be used in the right areas for performance improvement and enhancement, and the technology must be implemented carefully and safely” Sasha Jory, Hastings Direct

Hastings also uses Azure and AI to help staff write customer complaint letters. Jory says the company has used the technology to boost the readability of those letters from a score of 50 out of 100 to about 70. What’s more, the score is increasing all the time.

“That’s giving us a good outcome for our customers because they’re receiving a letter they can read,” she says. “It’s simple and means there’s less backwards and forwards with customers trying to understand their issues.”

Jory says Hastings’ initial explorations into AI show the technology can be used to make the business smarter. “It’s certainly something that we’re looking at all the time, but we’re very cautious,” she says.

“We’re not biting on the hype. We don’t think AI is the panacea for everything. AI must be used in the right areas for performance improvement and enhancement, and the technology must be implemented carefully and safely.”

JP Morgan Chase: Aim for data consistency

Gerard Francis, firm-wide product head for data and analytics at JP Morgan Chase and head of Fusion by JP Morgan, says his early explorations into AI suggest the technology will solve several business challenges across unstructured and structured data.

“The problems are better understood in the unstructured world, whether it’s techniques like retrieval or augmented generation of documents,” he says. “We’re doing a range of things to improve the experience with unstructured data and the use cases you can deal with, from customer service questions to legal issues.”

Francis says exploiting structured data should be seen as “the next wave” of AI. In an industry such as finance, there’s a surfeit of structured data, and people require accurate answers. Companies must consider how LLMs can help people generate this insight.

“I think that evolution will only continue,” he says. “We’ve focused on semantically correct data from the beginning. Very, very few people have semantically consistent data in the industry. And if you don’t get the semantics right, the LLM can’t work with the data.”

Francis explains semantics in more detail. Employees might use different codes, such as “MATUR” or “MAT”, for an industry term like maturity. LLMs will struggle to understand what those codes mean without direction. Definitions can also overlap.

“The same name might mean three different things depending upon who that data comes from,” he says. “If you ask a question, the LLM might translate it using a description, but it might give an incorrect answer because it has a different interpretation of that word. JP Morgan works with many customers and lots of data, so we’ve created a common definition for all the business terms that somebody would use in financial markets.”

This semantic consistency is producing great results. “It’s a big investment by JP Morgan to build this technology. We’ve hired some of the most talented people in the industry to make it work,” says Francis.

“We exist to make our clients happy and ensure we provide them with great service. For us, AI is about making that investment with an eye to the future and continuing to grow.”

Scania: Faster and simpler

Ulf Holmström, lead data scientist at Scania Group, says his business is keen to make the most of AI. His team ensures the company focuses on the right areas.

“We have explored GenAI, but it’s not in production yet,” he says. “We have started with internal support, rather than customer-facing, processes. However, what you can do with this technology is mind-blowing.”

Holmström says Scania is exploring GenAI through Amazon Web Services (AWS) technology. The company has been running its explorations for a year and has seen some “good results”. Scania is also interested in the technologies being developed by Snowflake, particularly Cortex.

“Based on my experience, if Snowflake delivers on its promises, then we can build generative applications faster and simpler,” he says. “I am impressed because we’ve been working hard with AWS Bedrock. Snowflake is putting another abstraction layer on top of the technology from the cloud vendors.”

Scania uses a data mesh built on Snowflake’s platform to generate insight-led services for customers. Today, the company has around 60 Snowflake accounts. Holmström is keen to explore how this foundation can create a trusted platform for AI.

“With our mesh, we know we can trust our data,” he says. “We can focus on solving business problems and let Snowflake and AWS deal with the tech stack. It’s almost like self-serve AI.”

Eutelsat: Identify your key challenges

Miguel Morgado, senior product owner for the performance hub at Eutelsat Group, says most of the satellite company’s AI projects are focused on outage prediction and root cause analysis. One of the key use cases is weather prediction.

“Weather events, like a cyclone, storm or heavy rain, can affect satellite dishes,” he says. “All the satellite operators have mitigations, such as increasing the signal power during heavy rain. Real-time weather data can help us predict when the weather will affect user terminals in each region and provide the best customer service.”

Eutelsat gives its customers service guarantees. Data and AI can help the company ensure it meets service-level agreements. Morgado explains how his organisation feeds data sources into Snowflake and runs algorithms to generate insights.

“It’s all done by us in-house,” he says. “We don’t use ChatGPT, Mistral or anything else. We plan to use Cortex for certain use cases. We’ll work on that area during the next six months. We’re already doing a proof of concept. We are testing the waters.”

Morgado says his firm’s explorations into AI suggest challenges must be overcome. One of the key issues is ensuring the business has access to a knowledge graph, a collection of interlinked descriptions of entities that puts data into context and enables analytics and collaboration.

“The problem with AI is that it’s easy to say, ‘Tell me how my satellite is doing.’ And the system will say, ‘It’s in service.’ However, it’s difficult to ask, ‘How is our network performance in London?’ That question is difficult to answer because you need a knowledge graph on top of your data and AI.”

Morgado says Eutelsat is working with RelationAI to explore how its knowledge graph runs on the Snowflake platform: “One of the big challenges for us is how we can use AI and knowledge graphs – and that is what we are testing.”

Read more about implementing GenAI

• Data management key to GenAI success - Deloitte survey shows business and IT leaders are optimistic, but academic researchers warn of AI training time bomb.
• Workers and business leaders have different views on GenAI uses - Employees are using GenAI primarily for spelling and grammar checking, while business chiefs are using it for data analysis.
• Massive hyperscaler GenAI spend raises questions on costs - How much will IT buyers be expected to pay, as hyperscalers ramp up investment in AI-powered servers to support GenAI?

Read more on Artificial intelligence, automation and robotics

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Nearly a third of GenAI projects to be dropped after PoC

DBS rolls out GenAI assistant for customer service teams

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As global climate change intensifies, accurate weather forecasting is increasingly crucial for sectors such as agriculture, energy management, and environmental protection. Traditional methods, which rely on physical and statistical models, often struggle with complex, nonlinear, and time-varying data, underscoring the need for more advanced techniques. This study explores a hybrid CNN-LSTM model to enhance temperature forecasting accuracy for the Delhi region, using historical meteorological data from 1996 to 2017. We employed both direct and indirect methods, including comprehensive data preprocessing and exploratory analysis, to construct and train our model. The CNN component effectively extracts spatial features, while the LSTM captures temporal dependencies, leading to improved prediction accuracy. Experimental results indicate that the CNN-LSTM model significantly outperforms traditional forecasting methods in terms of both accuracy and stability, with a mean square error (MSE) of 3.26217 and a root mean square error (RMSE) of 1.80615. The hybrid model demonstrates its potential as a robust tool for temperature prediction, offering valuable insights for meteorological forecasting and related fields. Future research should focus on optimizing model architecture, exploring additional feature extraction techniques, and addressing challenges such as overfitting and computational complexity. This approach not only advances temperature forecasting but also provides a foundation for applying deep learning to other time series forecasting tasks.

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Non-HACEK gram-negative bacilli infective endocarditis: data from a retrospective German cohort study

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• Published: 19 September 2024

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• Juliane Dörfler   ORCID: orcid.org/0009-0008-8642-6067 1 ,
• Herko Grubitzsch 2 , 4 ,
• Matthias Schneider-Reigbert 3 , 4 , 5 ,
• Miralem Pasic 2 , 4 ,
• Frieder Pfäfflin 1 ,
• Miriam Stegemann 1 ,
• Leif E. Sander 1 , 6 , 7 ,
• Florian Kurth 1 &
• Tilman Lingscheid 1  

Infective endocarditis caused by non-HACEK gram-negative bacilli (GNB-IE) is rare but associated with significant morbidity and case fatality. Evidence on optimal treatment and management is limited. We aimed to describe the characteristics and management of GNB-IE patients, investigating factors associated with disease acquisition and unfavorable outcomes.

We conducted a retrospective descriptive single-center study (tertiary care and referral hospital) between 2015 and 2021, including adult patients with definite GNB-IE. We reviewed demographic, clinical and microbiological data, focusing on predisposing factors, clinical outcomes and 1-year mortality.

Of 1093 patients with probable or definite IE, 19 patients (median age 69 years) had definite GNB-IE, with an increasing incidence throughout the study period. Median age-adjusted Charlson Comorbidity Index score was 4 points. Prosthetic valve IE (PVIE) was present in 7/19 (37%) patients. Nosocomial acquisition occurred in 8/19 (42%) patients. Escherichia coli and Klebsiella pneumoniae were the most common pathogens. Beta-lactam (BL) based combination therapy was applied in 12/19 (63%) patients (58% BL + fluoroquinolone, 42% BL + aminoglycoside). Cardiac surgery was required in 8/19 (42%) patients (PVIE 71%, native valve IE 25%), primarily for embolism prevention and heart failure. Complications occurred in 14/19 (74%) patients. The in-hospital mortality rate was 21% (4/19); the one-year mortality rate was 44% (7/16). One-year mortality did not significantly differ between patients who underwent cardiac surgery and patients managed with anti-infective treatment alone ( p  = 0.633).

Conclusions

GNB-IE affects elderly patients with high comorbidity levels and recent health-care exposure. GNB-IE was associated with high complication rates and high mortality.

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Introduction

Infective endocarditis (IE) due to gram-negative bacilli (GNB) not included in the HACEK group (Haemophilus, Aggregatibacter spp., Cardiobacterium, Eikenella corrodens , and Kingella spp.) constitutes 2–3% of IE cases [ 1 , 2 ]. However, non-HACEK GNB-IE is increasingly recognized as an emerging infectious disease (ID) entity with elevated morbidity and mortality [ 1 , 2 , 3 , 4 ]. Recent research indicated an increase in non-HACEK GNB-IE cases, with incidences ranging from approximately 1.8% [ 2 ] to 3.9% [ 3 , 5 ]. These observations have prompted a proposal to update the modified Duke Criteria by including certain gram-negative bacilli as a major criterion for IE, particularly in cases involving intracardiac prosthetic material [ 6 ].

The main predisposing factors for non-HACEK GNB-IE include advanced age, increased comorbidity, recent health-care contact, immunosuppression, central catheter infections and the presence of a prosthetic heart valve [ 1 , 2 , 3 ]. International guidelines now recommend a prolonged combination antibiotic therapy (CT) for non-HACEK GNB-IEs based on beta-lactam antibiotics (BL) and aminoglycosides, and in some cases with the addition of fluoroquinolones or cotrimoxazole [ 7 ]. Early surgical intervention is recommended, particularly in the case of a prosthetic valve IE (PVIE) [ 7 , 8 ]. The latest European Society of Cardiology (ESC) guidelines reflected the growing research focus on non-HACEK GNB-IE by underscoring the importance of managing GNB-IE [ 7 ]. However, due to the rarity of non-HACEK GNB-IE, diagnosis can be delayed, and evidence on optimal anti-infective treatment and the indication and timing of cardiac surgery is limited [ 1 ]. Emerging drug-resistance among GNB strains poses additional challenges in the management of patients with GNB-IE [ 7 ].

To the best of our knowledge, no previous studies have investigated the characteristics and outcomes of patients with IE due to non-HACEK GNB in the German health-care setting. In this light, the objective of this retrospective descriptive study was to fill up the evidence gap by providing a detailed description of the predisposing factors, clinical features, management and outcomes of patients diagnosed with non-HACEK GNB-IE at a large IE referral center in Germany.

We conducted a retrospective descriptive single-center study at Charité – Berlin University Hospital, a tertiary care hospital and referral center for IE patients for conservative management as well as surgical therapy.

We applied the following screening methods to assess study eligibility: first, we identified patients with IE due to non-HACEK GNB-IE who were consulted by an ID specialist between 2015 and 2021. In addition, through a review of a pseudonymized extract derived from electronic medical records, we identified patients who were diagnosed with the ICD-10 case codes I33 (“endocarditis”) and B96 (“other specified bacterial agents as the cause of diseases classified to other chapters”, meaning gram-negative bacteria), who were treated in the departments of ID, cardiology or cardio-surgery between 2015 and 2021. The eligibility of the identified patients for the study was then confirmed by a review of the patients’ electronic medical records. We included adult patients who met the criteria for definite non-HACEK GNB-IE based on the 2015 ESC diagnostic criteria for IE [ 9 ], and who were hospitalized at Charité Hospital between 2015 and 2021. Patients were excluded from the study if the diagnosis of IE was discarded, if blood cultures showed no growth, gram-positive growth, or polymicrobial growth; or if HACEK organisms or fungi were identified in blood cultures.

Epidemiological and clinical data were collected retrospectively from patients’ electronic medical records. Nosocomial IE was defined as IE that developed in a patient who had been hospitalized for more than 48 h prior to the onset of signs or symptoms consistent with IE or an infection in general. Comorbidities were assessed with the age-adjusted Charlson Comorbidity Index (ACCI) [ 10 ].

Based on previous literature, we considered the following predisposing factors for non-HACEK GNB-IE: the presence of a prosthetic valve (PV), defined as the presence of a biological or mechanical prosthetic heart valve; the presence of central intravascular catheters (CVCs); and immunosuppression.

Following the 2015 ESC guidelines for the management of IE, we defined combination antibiotic therapy (CT) as the use of a beta-lactam (BL) in combination with an aminoglycoside or fluoroquinolone [ 9 ]. Monotherapy was defined as the use of a single BL antibiotic agent. Treatment regimens that did not include any BLs were categorized as “other”.

The indications for cardiac surgery, including embolism prevention, uncontrolled infection and heart failure, were considered in line with ESC guidelines. Uncontrolled infection was defined as persistent positive blood cultures for more than seven days despite adequate antimicrobial therapy, or locally uncontrolled infections such as cardiac abscesses, pseudoaneurysms, fistulae or enlarging vegetations. Heart failure included dyspnea (NYHA ≥ III), refractory pulmonary edema or cardiogenic shock due to severe heart valve regurgitation or stenosis [ 9 ].

Any complication that occurred during the hospital stay was analyzed. Infectious complications included septic shock, persistent bacteremia, secondary infectious foci and sepsis-associated encephalopathy. Thromboembolic or septic embolic events were categorized as embolic events. Cardiac complications included new valvular lesions (regurgitation and/or stenosis ≥ II°) and perivalvular infection. Organ failure included heart failure (as previously defined) and any documented dysfunction or impairment of one or more organs resulting from the infection. In-hospital mortality and 1-year mortality were defined as death from any cause during the hospital stay and at one year after discharge, respectively.

We conducted a retrospective analysis applying descriptive statistics. Continuous variables were regarded as nonnormally distributed and are presented as medians and 25th and 75th interquartile ranges (IQRs). Frequencies (n) and proportions (%) are provided for categorical variables. Quantitative variables were compared using the Mann-Whitney U test. Comparisons of categorical variables were made by either chi-square test or Fisher’s exact test, if the frequency in one group was less than five.

Group comparisons were conducted among predefined subgroups to compare epidemiological and clinical data, as well as management and outcome, between patients with PVIE and patients with native valve IE (NVIE). Additionally, we compared mortality rates between patients who required cardiac surgery in addition to anti-infective therapy, and those managed with anti-infective therapy alone.

For all tests, a p value of ≤ 0.05 was considered to indicate statistical significance. Statistical analysis was performed using JMP ® Pro 17.1.0 (copyright © 2022–2023 JMP Statistical Discovery LLC. All Rights Reserved.)

The study was performed in accordance with the principles of the Declaration of Helsinki. The need for informed consent was waived in line with the applicable local law (§ 25 LKHG Bln), as data and samples were analyzed retrospectively, and the study was noninterventional in nature.

Of the 1093 patients treated at Charité between 2015 and 2021 who were screened for eligibility, 19 had definite non-HACEK GNB-IE. Figure  1 shows a summary of the patient screening and inclusion process.

Screening and inclusion process

Epidemiology, baseline characteristics, echocardiography, microbiology

Between 2015 and 2021, 19 patients with definite non-HACEK GNB-IE were diagnosed and treated at our hospital. Throughout the study period, the incidence of non-HACEK GNB-IE increased; a single case of non-HACEK GNB-IE was observed in 2015, followed by three cases in 2018, four cases in both 2019 and 2020, and seven cases in 2021. For three patients, information regarding the endpoint of mortality at one year was unavailable.

Table  1 shows the participants’ baseline characteristics and predisposing factors. The median age at admission was 69 years (IQR 53–76), and 13 participants (13/19, 68%) were male. The median age-adjusted Charlson Comorbidity Index was 4 points (IQR 2–6). Three participants (3/19, 15%) had a history of previous IE. Vegetations were primarily found on the aortic valve (13/19, 68%) and the mitral valve (5/19, 26%). In one participant, both the aortic and mitral valves were affected. There were no cases of right-sided GNB-IE.

Eight patients (8/19, 42%) met the criteria for nosocomial IE. Predisposing factors were identified in 68% (13/19) of the patients, among whom 54% (7/13) had a prosthetic heart valve, 46% (6/13) had a central venous catheter and 31% (4/13) were immunosuppressed. None of our participants reported intravenous drug use.

The PVIE cohort included seven patients with prosthetic valve endoplastitis. All of them were operated via conventional surgery: five with a biological aortic valve prosthesis, one with a biological mitral valve prosthesis, and one with a mechanical mitral valve prosthesis. Endoplastitis occurred within the first two months after surgery in three patients. In the remaining four patients, it occurred 1, 3, 5, or 14 years after surgery. The initial indications for surgery were severe stenosis of the native valve in five patients (73–87 years old), and endocarditis in two patients (32 and 53 years old). One patient diagnosed with endoplastitis of their biological mitral valve had a second prosthetic valve; this biological aortic valve had been implanted in a separate procedure using transcatheter intervention and was not affected by endoplastitis. Figure  2 shows the transesophageal echocardiography findings of two patients with PVIE.

Transesophageal echocardiography findings of two PVIE patients from the analyzed cohort. One patient with native mitral valve endocarditis with a large vegetation on the posterior mitral valve leaflet (Panel A ) and severe mitral regurgitation. ( B ) The other patient with prosthetic aortic valve endoplastitis ( C ) and severe valvular stenosis caused by large vegetations ( D )

The majority of patients (16/19, 84%) had one or multiple possible sources of infection. Urinary tract infections were the most common possible source of infection (8/16, 50%), followed by central venous catheter infections (5/16, 31%) and gastrointestinal infections (4/16, 25%). Two participants (2/16, 13%) presented with orodental infections, two participants (2/16, 13%) had a pulmonary source of infection, and one participant (1/16, 6%) had a soft tissue infection at admission. In the remaining three patients, no source of infection was identified, and IE was thus categorized as primary blood stream infection.

All participants in the study exhibited positive blood cultures. The most commonly isolated pathogens from blood cultures were Enterobacterales (14/19, 74%), including Escherichia coli (5/19, 26%), Klebsiella pneumoniae (5/19, 26%), Proteus mirabilis (3/19, 17%) and Enterobacter cloacae (1/19, 5%). In six patients (6/19, 32%), the causative microorganism was additionally confirmed by molecular or pathological analysis of intraoperative specimens or by microbiological findings from a valve culture. Only one patient presented with a multidrug-resistant pathogen, namely, an Oxa-48-carbapenemase-producing Klebsiella pneumoniae. A detailed list of all pathogens can be found in Table  S3 in the Supplement.

Treatment, clinical course, outcome

Each patient received a consultation from an ID specialist who recommended parenteral antibiotic treatment in accordance with the guideline recommendations. The recommended treatment duration was six weeks, either following the first negative blood culture or after cardiac surgery, if pathogens were cultured from surgical material. For one patient, parenteral antibiotic therapy was converted to an oral regimen with an antibiotic from the same class as the initial parenteral treatment.

The treatment, clinical course and outcome data are summarized in Table  2 . Among the patients who received the recommended combination antibiotic therapy (12/19, 63%), 7/12 (58%) received a BL antibiotic with a fluoroquinolone, and 5/12 (42%) were treated with a BL and an aminoglycoside. Six patients (6/19, 32%) received BL monotherapy. One patient (1/19, 5%) received fluoroquinolone monotherapy. A detailed overview of the causative pathogens, the applied antibiotic therapy and the minimum inhibitory concentrations (MICs) from patients’ resistograms are shown in the supplemental material (Supplement: Table  3 ).

In-hospital complications occurred in 14/19 (74%) patients, and 8/19 (42%) patients developed two or more complications during their stay. Most patients developed cardiac complications (8/14, 57%), such as cardiac abscesses or new valvular lesions, followed by embolic events (6/14, 43%) and infectious complications (6/14, 43%), such as septic shock, spondylodiscitis or septic encephalopathy. Organ failure occurred in 8/14 (57%) patients.

Cardiac surgery was performed in 8/19 (42%) patients. The majority of patients who underwent cardiac surgery had PVIE (5/8, 63%), and most patients had more than one indication for cardiac surgery. The most common indication for cardiac surgery was embolism prevention in 6/8 (75%) patients, followed by heart failure (5/8, 63%) and uncontrolled infection (3/8, 38%). Nine patients (9/19, 53%) had no indication for cardiac surgery and did not receive surgical intervention, while in two patients (2/19, 12%) surgery, although formally indicated, was not performed due to a prohibitive operative risk. Of these two patients, one was lost to follow-up after returning to their home country, and the other died within 60 days post-discharge.

The in-hospital mortality rate was 21% (4/19), and the most common cause of death was multiorgan failure (3/4, 75%). The overall one-year mortality was 44% (7/16).

Group comparisons between patients with PVIE and patients with native-valve IE (NVIE) revealed no statistically significant differences in clinical outcomes, complication rates, cardiac surgery rates, in-hospital mortality or 1-year mortality (Table  2 ).

Similarly, we observed no statistically significant differences in mortality rates between patients who underwent cardiac surgery and those who received anti-infective treatment alone. This held true for both in-hospital mortality (25% vs. 18%, p  = 1.0), as well as 1-year mortality (25% vs. 45%, p  = 0.633).

To the best of our knowledge, this is the first study to describe the characteristics and outcomes of patients with non-HACEK GNB-IE in Germany.

The principal findings of our study highlight the significant clinical severity and high mortality observed among patients with non-HACEK GNB-IE. One-fifth of patients died during hospitalization, and nearly one half died within the first year after discharge. In recent multicenter studies, comparable morality rates in IE due to non-HACEK GNB-IE were observed, ranging from 14% to 47% [ 1 , 2 , 3 , 11 ]. Elevated mortality in patients with non-HACEK GNB-IE has been associated with advanced age, PVIE, and not undergoing cardiac surgery [ 1 , 11 , 12 ]. However, the decision to forgo surgery can be multifactorial and complex and is frequently driven by the high risk of intraoperative mortality due to patient morbidity.

The high mortality rate observed in our study may be attributable to the distinctive risk profile of advanced age and increased comorbidity characteristic of patients with non-HACEK GNB-IE and may have been compounded by the high rate of complications [ 1 , 2 , 3 , 5 ]. In line with recent literature, patients with non-HACEK GNB-IE in our study were older than a representative cohort of patients in the International Collaboration on Infective Endocarditis study who had IE due to other microorganisms [ 2 ]. We observed high comorbidity levels measured by the ACCI [ 1 ]; however, comparisons with a representative group of patients with IE due to other causes were limited by heterogeneous measurements. Despite the male predominance, the proportion of male patients with non-HACEK GNB-IE in our cohort was comparable to that of patients with IE due to other microorganisms [ 2 ].

In our study, the majority of patients received a BL-based CT, as it is currently recommended by international guidelines. The current recommendations for non-HACEK GNB-IE anti-infective therapy are primarily based on expert opinion or past guidelines, advocating for a combination of a BL with an aminoglycoside, sometimes with additional fluoroquinolones or cotrimoxazole [ 7 , 8 , 13 ]. However, previous cohort studies do not provide strong evidence on the superiority of a CT over a BL-based monotherapy for non-HACEK GNB-IE, and both treatment approaches demonstrate similar mortality rates [ 1 , 2 , 14 , 15 ]. One recent retrospective cohort study reported increased readmission rates in patients who received CT, which may be attributed to increased toxicity associated with the administration of non-BL antibiotics [ 11 ]. Given the potential toxicity of combination agents such as aminoglycosides and the lack of evidence of the superiority of CT over BL monotherapy, the routine use of CT should be questioned.

The rates of cardiac surgery in our study were consistent with those reported in prior studies [ 1 , 2 , 16 , 17 , 18 ]. In accordance with current guideline recommendations, the majority of patients diagnosed with PVIE underwent cardiac surgery, whereas only one-quarter of patients with NVIE required surgical intervention. One-year post-discharge mortality did not significantly differ between patients who underwent cardiac surgery and those managed with anti-infective treatment alone. Surgery is recognized as a key pillar in the management of IE due to non-HACEK GNB, especially in the case of prosthetic valve IE [ 7 ]. This intervention is considered crucial for pathogen eradication and for mitigating the risk of complications and antibacterial resistance [ 9 , 19 ]. A recent study including 104 patients with non-HACEK GNB-IE revealed that not performing surgery despite indications was associated with a higher mortality rate [ 1 ]. However, in line with our results, several studies reported no difference in outcomes in patients with non-HACEK GNB-IE who received cardiac surgery compared to patients who were managed medically [ 1 , 2 , 15 , 18 ]. It could be concluded that surgical intervention for patients with more severe IE might achieve outcomes comparable to those of anti-infective therapy in patients with less severe non-HACEK GNB-IE.

It is essential to acknowledge the limitations imposed by the small study cohort, the diverse microorganism profiles and the limited duration of patient follow-up, preventing definitive conclusions regarding the indications for cardiac surgery. Larger prospective cohort studies are needed to determine the role of surgical intervention in the management of non-HACEK GNB-IE, ideally in relation to the causative GNB. The interdisciplinary complexity of managing IE patients has been recognized, and a recent systematic review and meta-analysis demonstrated the positive impact of dedicated multidisciplinary IE teams on surgical and patient outcomes, including lower short-term mortality rates [ 20 ]. During the timeframe of the current study, IE cases were discussed regularly by an interdisciplinary IE team. Given the severity and high mortality of the disease, there is a critical need for the multidisciplinary IE team to be involved in the management of IE due to non-HACEK GNB-IE.

Consistent with previous studies, we observed a high rate of nosocomial IE. Accordingly, most patients exhibited a combination of healthcare-associated risk factors for GNB-IE, such as prosthetic heart valves, CVCs or intracardiac devices [ 1 , 2 , 15 ]. An overall increase in valve replacement surgeries among elderly patients has been reported, resulting in a greater proportion of PVIE within the GNB-IE patient population [ 12 , 21 , 22 ]. A recent study reported that one to six percent of all patients with heart valve prostheses were diagnosed with PVIE. Furthermore, more than 20% of all cases of IE were classified as PVIE [ 4 ]. These observations highlight the importance of previous health-care contact and related invasive medical procedures as major risk factors for the development of non-HACEK GNB-IE. In contrast to previous studies that have linked non-HACEK GNB-IE to intravenous drug use [ 11 , 15 ], none of our patients reported such behavior.

In line with recent studies, IE due to Enterobacterales was more frequent than IE due to nonfermenting GNB, with Escherichia coli and Klebsiella pneumoniae being the most prevalent pathogens [ 1 , 3 , 23 ]. Global reports have shown a rise in GNB-IE, which may be attributed to the growing proportion of GNB blood stream infections, particularly Enterobacterales [ 24 ], as well as to an increase in age and comorbidity levels in the hospitalized population. In line with previous studies, we found that urinary tract infections were the most common presumed source of infection for non-HACEK GNB-IE, highlighting their importance as an entry point for GNB [ 1 , 2 , 3 , 23 ].

Our study has several limitations. First, the retrospective nature of the study design may have introduced inherent biases due to the incompleteness and limited reliability of the electronic medical records as the main data source. Second, the study was conducted as a single-center study at one university hospital, and due to the low incidence of the disease, the sample size was small. Third, our university hospital may have served as a referral center for complicated IE cases with an indication for cardiac surgery, which may have led to selection bias with an overrepresentation of patients with complicated clinical trajectories. Last, the various statistical comparisons within a limited study sample size could have led to decreased precision in estimations and an increased likelihood of type I errors.

In conclusion, GNB-IE affects an elderly patient cohort with recent health-care contact and high comorbidity levels. Although recommended combination antibiotic therapy was applied in a majority of patients, we found high rates of complications, frequent indications for cardiac surgery and high mortality rates. In summary, in the case of persistent or recurrent bacteremia due to non-HACEK organisms, IE should be suspected, especially in elderly patients with health-care-associated risk factors. Case consultation by an ID specialist and the involvement of a multidisciplinary IE team are especially crucial for the successful management of patients with infective endocarditis caused by non-HACEK GNB.

Data availability

No datasets were generated or analysed during the current study.

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Conceptualization, JD and TL; writing - original draft preparation, JD and TL; writing - review and editing, HG, MSR, FP, MS, LES, FK, MP; Fig.  1 , JD; Fig.  2 , MSR. All authors have read and agreed to the published version of the manuscript.

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Dörfler, J., Grubitzsch, H., Schneider-Reigbert, M. et al. Non-HACEK gram-negative bacilli infective endocarditis: data from a retrospective German cohort study. Infection (2024). https://doi.org/10.1007/s15010-024-02392-w

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DOI : https://doi.org/10.1007/s15010-024-02392-w

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