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Chapter 3. Psychological Science
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3.2 Psychologists Use Descriptive, Correlational, and Experimental Research Designs to Understand Behaviour
Learning objectives.
- Differentiate the goals of descriptive, correlational, and experimental research designs and explain the advantages and disadvantages of each.
- Explain the goals of descriptive research and the statistical techniques used to interpret it.
- Summarize the uses of correlational research and describe why correlational research cannot be used to infer causality.
- Review the procedures of experimental research and explain how it can be used to draw causal inferences.
Psychologists agree that if their ideas and theories about human behaviour are to be taken seriously, they must be backed up by data. However, the research of different psychologists is designed with different goals in mind, and the different goals require different approaches. These varying approaches, summarized in Table 3.2, are known as research designs . A research design is the specific method a researcher uses to collect, analyze, and interpret data . Psychologists use three major types of research designs in their research, and each provides an essential avenue for scientific investigation. Descriptive research is research designed to provide a snapshot of the current state of affairs . Correlational research is research designed to discover relationships among variables and to allow the prediction of future events from present knowledge . Experimental research is research in which initial equivalence among research participants in more than one group is created, followed by a manipulation of a given experience for these groups and a measurement of the influence of the manipulation . Each of the three research designs varies according to its strengths and limitations, and it is important to understand how each differs.
Research design | Goal | Advantages | Disadvantages |
---|---|---|---|
Descriptive | To create a snapshot of the current state of affairs | Provides a relatively complete picture of what is occurring at a given time. Allows the development of questions for further study. | Does not assess relationships among variables. May be unethical if participants do not know they are being observed. |
Correlational | To assess the relationships between and among two or more variables | Allows testing of expected relationships between and among variables and the making of predictions. Can assess these relationships in everyday life events. | Cannot be used to draw inferences about the causal relationships between and among the variables. |
Experimental | To assess the causal impact of one or more experimental manipulations on a dependent variable | Allows drawing of conclusions about the causal relationships among variables. | Cannot experimentally manipulate many important variables. May be expensive and time consuming. |
Source: Stangor, 2011. |
Descriptive Research: Assessing the Current State of Affairs
Descriptive research is designed to create a snapshot of the current thoughts, feelings, or behaviour of individuals. This section reviews three types of descriptive research : case studies , surveys , and naturalistic observation (Figure 3.4).
Sometimes the data in a descriptive research project are based on only a small set of individuals, often only one person or a single small group. These research designs are known as case studies — descriptive records of one or more individual’s experiences and behaviour . Sometimes case studies involve ordinary individuals, as when developmental psychologist Jean Piaget used his observation of his own children to develop his stage theory of cognitive development. More frequently, case studies are conducted on individuals who have unusual or abnormal experiences or characteristics or who find themselves in particularly difficult or stressful situations. The assumption is that by carefully studying individuals who are socially marginal, who are experiencing unusual situations, or who are going through a difficult phase in their lives, we can learn something about human nature.
Sigmund Freud was a master of using the psychological difficulties of individuals to draw conclusions about basic psychological processes. Freud wrote case studies of some of his most interesting patients and used these careful examinations to develop his important theories of personality. One classic example is Freud’s description of “Little Hans,” a child whose fear of horses the psychoanalyst interpreted in terms of repressed sexual impulses and the Oedipus complex (Freud, 1909/1964).
Another well-known case study is Phineas Gage, a man whose thoughts and emotions were extensively studied by cognitive psychologists after a railroad spike was blasted through his skull in an accident. Although there are questions about the interpretation of this case study (Kotowicz, 2007), it did provide early evidence that the brain’s frontal lobe is involved in emotion and morality (Damasio et al., 2005). An interesting example of a case study in clinical psychology is described by Rokeach (1964), who investigated in detail the beliefs of and interactions among three patients with schizophrenia, all of whom were convinced they were Jesus Christ.
In other cases the data from descriptive research projects come in the form of a survey — a measure administered through either an interview or a written questionnaire to get a picture of the beliefs or behaviours of a sample of people of interest . The people chosen to participate in the research (known as the sample) are selected to be representative of all the people that the researcher wishes to know about (the population). In election polls, for instance, a sample is taken from the population of all “likely voters” in the upcoming elections.
The results of surveys may sometimes be rather mundane, such as “Nine out of 10 doctors prefer Tymenocin” or “The median income in the city of Hamilton is $46,712.” Yet other times (particularly in discussions of social behaviour), the results can be shocking: “More than 40,000 people are killed by gunfire in the United States every year” or “More than 60% of women between the ages of 50 and 60 suffer from depression.” Descriptive research is frequently used by psychologists to get an estimate of the prevalence (or incidence ) of psychological disorders.
A final type of descriptive research — known as naturalistic observation — is research based on the observation of everyday events . For instance, a developmental psychologist who watches children on a playground and describes what they say to each other while they play is conducting descriptive research, as is a biopsychologist who observes animals in their natural habitats. One example of observational research involves a systematic procedure known as the strange situation , used to get a picture of how adults and young children interact. The data that are collected in the strange situation are systematically coded in a coding sheet such as that shown in Table 3.3.
Coder name: | ||||
This table represents a sample coding sheet from an episode of the “strange situation,” in which an infant (usually about one year old) is observed playing in a room with two adults — the child’s mother and a stranger. Each of the four coding categories is scored by the coder from 1 (the baby makes no effort to engage in the behaviour) to 7 (the baby makes a significant effort to engage in the behaviour). More information about the meaning of the coding can be found in Ainsworth, Blehar, Waters, and Wall (1978). | ||||
Coding categories explained | ||||
Proximity | The baby moves toward, grasps, or climbs on the adult. | |||
Maintaining contact | The baby resists being put down by the adult by crying or trying to climb back up. | |||
Resistance | The baby pushes, hits, or squirms to be put down from the adult’s arms. | |||
Avoidance | The baby turns away or moves away from the adult. | |||
Episode | Coding categories | |||
---|---|---|---|---|
Proximity | Contact | Resistance | Avoidance | |
Mother and baby play alone | 1 | 1 | 1 | 1 |
Mother puts baby down | 4 | 1 | 1 | 1 |
Stranger enters room | 1 | 2 | 3 | 1 |
Mother leaves room; stranger plays with baby | 1 | 3 | 1 | 1 |
Mother re-enters, greets and may comfort baby, then leaves again | 4 | 2 | 1 | 2 |
Stranger tries to play with baby | 1 | 3 | 1 | 1 |
Mother re-enters and picks up baby | 6 | 6 | 1 | 2 |
Source: Stang0r, 2011. |
The results of descriptive research projects are analyzed using descriptive statistics — numbers that summarize the distribution of scores on a measured variable . Most variables have distributions similar to that shown in Figure 3.5 where most of the scores are located near the centre of the distribution, and the distribution is symmetrical and bell-shaped. A data distribution that is shaped like a bell is known as a normal distribution .
A distribution can be described in terms of its central tendency — that is, the point in the distribution around which the data are centred — and its dispersion, or spread . The arithmetic average, or arithmetic mean , symbolized by the letter M , is the most commonly used measure of central tendency . It is computed by calculating the sum of all the scores of the variable and dividing this sum by the number of participants in the distribution (denoted by the letter N ). In the data presented in Figure 3.5 the mean height of the students is 67.12 inches (170.5 cm). The sample mean is usually indicated by the letter M .
In some cases, however, the data distribution is not symmetrical. This occurs when there are one or more extreme scores (known as outliers ) at one end of the distribution. Consider, for instance, the variable of family income (see Figure 3.6), which includes an outlier (a value of $3,800,000). In this case the mean is not a good measure of central tendency. Although it appears from Figure 3.6 that the central tendency of the family income variable should be around $70,000, the mean family income is actually $223,960. The single very extreme income has a disproportionate impact on the mean, resulting in a value that does not well represent the central tendency.
The median is used as an alternative measure of central tendency when distributions are not symmetrical. The median is the score in the center of the distribution, meaning that 50% of the scores are greater than the median and 50% of the scores are less than the median . In our case, the median household income ($73,000) is a much better indication of central tendency than is the mean household income ($223,960).
A final measure of central tendency, known as the mode , represents the value that occurs most frequently in the distribution . You can see from Figure 3.6 that the mode for the family income variable is $93,000 (it occurs four times).
In addition to summarizing the central tendency of a distribution, descriptive statistics convey information about how the scores of the variable are spread around the central tendency. Dispersion refers to the extent to which the scores are all tightly clustered around the central tendency , as seen in Figure 3.7.
Or they may be more spread out away from it, as seen in Figure 3.8.
One simple measure of dispersion is to find the largest (the maximum ) and the smallest (the minimum ) observed values of the variable and to compute the range of the variable as the maximum observed score minus the minimum observed score. You can check that the range of the height variable in Figure 3.5 is 72 – 62 = 10. The standard deviation , symbolized as s , is the most commonly used measure of dispersion . Distributions with a larger standard deviation have more spread. The standard deviation of the height variable is s = 2.74, and the standard deviation of the family income variable is s = $745,337.
An advantage of descriptive research is that it attempts to capture the complexity of everyday behaviour. Case studies provide detailed information about a single person or a small group of people, surveys capture the thoughts or reported behaviours of a large population of people, and naturalistic observation objectively records the behaviour of people or animals as it occurs naturally. Thus descriptive research is used to provide a relatively complete understanding of what is currently happening.
Despite these advantages, descriptive research has a distinct disadvantage in that, although it allows us to get an idea of what is currently happening, it is usually limited to static pictures. Although descriptions of particular experiences may be interesting, they are not always transferable to other individuals in other situations, nor do they tell us exactly why specific behaviours or events occurred. For instance, descriptions of individuals who have suffered a stressful event, such as a war or an earthquake, can be used to understand the individuals’ reactions to the event but cannot tell us anything about the long-term effects of the stress. And because there is no comparison group that did not experience the stressful situation, we cannot know what these individuals would be like if they hadn’t had the stressful experience.
Correlational Research: Seeking Relationships among Variables
In contrast to descriptive research, which is designed primarily to provide static pictures, correlational research involves the measurement of two or more relevant variables and an assessment of the relationship between or among those variables. For instance, the variables of height and weight are systematically related (correlated) because taller people generally weigh more than shorter people. In the same way, study time and memory errors are also related, because the more time a person is given to study a list of words, the fewer errors he or she will make. When there are two variables in the research design, one of them is called the predictor variable and the other the outcome variable . The research design can be visualized as shown in Figure 3.9, where the curved arrow represents the expected correlation between these two variables.
One way of organizing the data from a correlational study with two variables is to graph the values of each of the measured variables using a scatter plot . As you can see in Figure 3.10 a scatter plot is a visual image of the relationship between two variables . A point is plotted for each individual at the intersection of his or her scores for the two variables. When the association between the variables on the scatter plot can be easily approximated with a straight line , as in parts (a) and (b) of Figure 3.10 the variables are said to have a linear relationship .
When the straight line indicates that individuals who have above-average values for one variable also tend to have above-average values for the other variable , as in part (a), the relationship is said to be positive linear . Examples of positive linear relationships include those between height and weight, between education and income, and between age and mathematical abilities in children. In each case, people who score higher on one of the variables also tend to score higher on the other variable. Negative linear relationships , in contrast, as shown in part (b), occur when above-average values for one variable tend to be associated with below-average values for the other variable. Examples of negative linear relationships include those between the age of a child and the number of diapers the child uses, and between practice on and errors made on a learning task. In these cases, people who score higher on one of the variables tend to score lower on the other variable.
Relationships between variables that cannot be described with a straight line are known as nonlinear relationships . Part (c) of Figure 3.10 shows a common pattern in which the distribution of the points is essentially random. In this case there is no relationship at all between the two variables, and they are said to be independent . Parts (d) and (e) of Figure 3.10 show patterns of association in which, although there is an association, the points are not well described by a single straight line. For instance, part (d) shows the type of relationship that frequently occurs between anxiety and performance. Increases in anxiety from low to moderate levels are associated with performance increases, whereas increases in anxiety from moderate to high levels are associated with decreases in performance. Relationships that change in direction and thus are not described by a single straight line are called curvilinear relationships .
The most common statistical measure of the strength of linear relationships among variables is the Pearson correlation coefficient , which is symbolized by the letter r . The value of the correlation coefficient ranges from r = –1.00 to r = +1.00. The direction of the linear relationship is indicated by the sign of the correlation coefficient. Positive values of r (such as r = .54 or r = .67) indicate that the relationship is positive linear (i.e., the pattern of the dots on the scatter plot runs from the lower left to the upper right), whereas negative values of r (such as r = –.30 or r = –.72) indicate negative linear relationships (i.e., the dots run from the upper left to the lower right). The strength of the linear relationship is indexed by the distance of the correlation coefficient from zero (its absolute value). For instance, r = –.54 is a stronger relationship than r = .30, and r = .72 is a stronger relationship than r = –.57. Because the Pearson correlation coefficient only measures linear relationships, variables that have curvilinear relationships are not well described by r , and the observed correlation will be close to zero.
It is also possible to study relationships among more than two measures at the same time. A research design in which more than one predictor variable is used to predict a single outcome variable is analyzed through multiple regression (Aiken & West, 1991). Multiple regression is a statistical technique, based on correlation coefficients among variables, that allows predicting a single outcome variable from more than one predictor variable . For instance, Figure 3.11 shows a multiple regression analysis in which three predictor variables (Salary, job satisfaction, and years employed) are used to predict a single outcome (job performance). The use of multiple regression analysis shows an important advantage of correlational research designs — they can be used to make predictions about a person’s likely score on an outcome variable (e.g., job performance) based on knowledge of other variables.
An important limitation of correlational research designs is that they cannot be used to draw conclusions about the causal relationships among the measured variables. Consider, for instance, a researcher who has hypothesized that viewing violent behaviour will cause increased aggressive play in children. He has collected, from a sample of Grade 4 children, a measure of how many violent television shows each child views during the week, as well as a measure of how aggressively each child plays on the school playground. From his collected data, the researcher discovers a positive correlation between the two measured variables.
Although this positive correlation appears to support the researcher’s hypothesis, it cannot be taken to indicate that viewing violent television causes aggressive behaviour. Although the researcher is tempted to assume that viewing violent television causes aggressive play, there are other possibilities. One alternative possibility is that the causal direction is exactly opposite from what has been hypothesized. Perhaps children who have behaved aggressively at school develop residual excitement that leads them to want to watch violent television shows at home (Figure 3.13):
Although this possibility may seem less likely, there is no way to rule out the possibility of such reverse causation on the basis of this observed correlation. It is also possible that both causal directions are operating and that the two variables cause each other (Figure 3.14).
Still another possible explanation for the observed correlation is that it has been produced by the presence of a common-causal variable (also known as a third variable ). A common-causal variable is a variable that is not part of the research hypothesis but that causes both the predictor and the outcome variable and thus produces the observed correlation between them . In our example, a potential common-causal variable is the discipline style of the children’s parents. Parents who use a harsh and punitive discipline style may produce children who like to watch violent television and who also behave aggressively in comparison to children whose parents use less harsh discipline (Figure 3.15)
In this case, television viewing and aggressive play would be positively correlated (as indicated by the curved arrow between them), even though neither one caused the other but they were both caused by the discipline style of the parents (the straight arrows). When the predictor and outcome variables are both caused by a common-causal variable, the observed relationship between them is said to be spurious . A spurious relationship is a relationship between two variables in which a common-causal variable produces and “explains away” the relationship . If effects of the common-causal variable were taken away, or controlled for, the relationship between the predictor and outcome variables would disappear. In the example, the relationship between aggression and television viewing might be spurious because by controlling for the effect of the parents’ disciplining style, the relationship between television viewing and aggressive behaviour might go away.
Common-causal variables in correlational research designs can be thought of as mystery variables because, as they have not been measured, their presence and identity are usually unknown to the researcher. Since it is not possible to measure every variable that could cause both the predictor and outcome variables, the existence of an unknown common-causal variable is always a possibility. For this reason, we are left with the basic limitation of correlational research: correlation does not demonstrate causation. It is important that when you read about correlational research projects, you keep in mind the possibility of spurious relationships, and be sure to interpret the findings appropriately. Although correlational research is sometimes reported as demonstrating causality without any mention being made of the possibility of reverse causation or common-causal variables, informed consumers of research, like you, are aware of these interpretational problems.
In sum, correlational research designs have both strengths and limitations. One strength is that they can be used when experimental research is not possible because the predictor variables cannot be manipulated. Correlational designs also have the advantage of allowing the researcher to study behaviour as it occurs in everyday life. And we can also use correlational designs to make predictions — for instance, to predict from the scores on their battery of tests the success of job trainees during a training session. But we cannot use such correlational information to determine whether the training caused better job performance. For that, researchers rely on experiments.
Experimental Research: Understanding the Causes of Behaviour
The goal of experimental research design is to provide more definitive conclusions about the causal relationships among the variables in the research hypothesis than is available from correlational designs. In an experimental research design, the variables of interest are called the independent variable (or variables ) and the dependent variable . The independent variable in an experiment is the causing variable that is created (manipulated) by the experimenter . The dependent variable in an experiment is a measured variable that is expected to be influenced by the experimental manipulation . The research hypothesis suggests that the manipulated independent variable or variables will cause changes in the measured dependent variables. We can diagram the research hypothesis by using an arrow that points in one direction. This demonstrates the expected direction of causality (Figure 3.16):
Research Focus: Video Games and Aggression
Consider an experiment conducted by Anderson and Dill (2000). The study was designed to test the hypothesis that viewing violent video games would increase aggressive behaviour. In this research, male and female undergraduates from Iowa State University were given a chance to play with either a violent video game (Wolfenstein 3D) or a nonviolent video game (Myst). During the experimental session, the participants played their assigned video games for 15 minutes. Then, after the play, each participant played a competitive game with an opponent in which the participant could deliver blasts of white noise through the earphones of the opponent. The operational definition of the dependent variable (aggressive behaviour) was the level and duration of noise delivered to the opponent. The design of the experiment is shown in Figure 3.17
Two advantages of the experimental research design are (a) the assurance that the independent variable (also known as the experimental manipulation ) occurs prior to the measured dependent variable, and (b) the creation of initial equivalence between the conditions of the experiment (in this case by using random assignment to conditions).
Experimental designs have two very nice features. For one, they guarantee that the independent variable occurs prior to the measurement of the dependent variable. This eliminates the possibility of reverse causation. Second, the influence of common-causal variables is controlled, and thus eliminated, by creating initial equivalence among the participants in each of the experimental conditions before the manipulation occurs.
The most common method of creating equivalence among the experimental conditions is through random assignment to conditions, a procedure in which the condition that each participant is assigned to is determined through a random process, such as drawing numbers out of an envelope or using a random number table . Anderson and Dill first randomly assigned about 100 participants to each of their two groups (Group A and Group B). Because they used random assignment to conditions, they could be confident that, before the experimental manipulation occurred, the students in Group A were, on average, equivalent to the students in Group B on every possible variable, including variables that are likely to be related to aggression, such as parental discipline style, peer relationships, hormone levels, diet — and in fact everything else.
Then, after they had created initial equivalence, Anderson and Dill created the experimental manipulation — they had the participants in Group A play the violent game and the participants in Group B play the nonviolent game. Then they compared the dependent variable (the white noise blasts) between the two groups, finding that the students who had viewed the violent video game gave significantly longer noise blasts than did the students who had played the nonviolent game.
Anderson and Dill had from the outset created initial equivalence between the groups. This initial equivalence allowed them to observe differences in the white noise levels between the two groups after the experimental manipulation, leading to the conclusion that it was the independent variable (and not some other variable) that caused these differences. The idea is that the only thing that was different between the students in the two groups was the video game they had played.
Despite the advantage of determining causation, experiments do have limitations. One is that they are often conducted in laboratory situations rather than in the everyday lives of people. Therefore, we do not know whether results that we find in a laboratory setting will necessarily hold up in everyday life. Second, and more important, is that some of the most interesting and key social variables cannot be experimentally manipulated. If we want to study the influence of the size of a mob on the destructiveness of its behaviour, or to compare the personality characteristics of people who join suicide cults with those of people who do not join such cults, these relationships must be assessed using correlational designs, because it is simply not possible to experimentally manipulate these variables.
Key Takeaways
- Descriptive, correlational, and experimental research designs are used to collect and analyze data.
- Descriptive designs include case studies, surveys, and naturalistic observation. The goal of these designs is to get a picture of the current thoughts, feelings, or behaviours in a given group of people. Descriptive research is summarized using descriptive statistics.
- Correlational research designs measure two or more relevant variables and assess a relationship between or among them. The variables may be presented on a scatter plot to visually show the relationships. The Pearson Correlation Coefficient ( r ) is a measure of the strength of linear relationship between two variables.
- Common-causal variables may cause both the predictor and outcome variable in a correlational design, producing a spurious relationship. The possibility of common-causal variables makes it impossible to draw causal conclusions from correlational research designs.
- Experimental research involves the manipulation of an independent variable and the measurement of a dependent variable. Random assignment to conditions is normally used to create initial equivalence between the groups, allowing researchers to draw causal conclusions.
Exercises and Critical Thinking
- There is a negative correlation between the row that a student sits in in a large class (when the rows are numbered from front to back) and his or her final grade in the class. Do you think this represents a causal relationship or a spurious relationship, and why?
- Think of two variables (other than those mentioned in this book) that are likely to be correlated, but in which the correlation is probably spurious. What is the likely common-causal variable that is producing the relationship?
- Imagine a researcher wants to test the hypothesis that participating in psychotherapy will cause a decrease in reported anxiety. Describe the type of research design the investigator might use to draw this conclusion. What would be the independent and dependent variables in the research?
Image Attributions
Figure 3.4: “ Reading newspaper ” by Alaskan Dude (http://commons.wikimedia.org/wiki/File:Reading_newspaper.jpg) is licensed under CC BY 2.0
Aiken, L., & West, S. (1991). Multiple regression: Testing and interpreting interactions . Newbury Park, CA: Sage.
Ainsworth, M. S., Blehar, M. C., Waters, E., & Wall, S. (1978). Patterns of attachment: A psychological study of the strange situation . Hillsdale, NJ: Lawrence Erlbaum Associates.
Anderson, C. A., & Dill, K. E. (2000). Video games and aggressive thoughts, feelings, and behavior in the laboratory and in life. Journal of Personality and Social Psychology, 78 (4), 772–790.
Damasio, H., Grabowski, T., Frank, R., Galaburda, A. M., Damasio, A. R., Cacioppo, J. T., & Berntson, G. G. (2005). The return of Phineas Gage: Clues about the brain from the skull of a famous patient. In Social neuroscience: Key readings. (pp. 21–28). New York, NY: Psychology Press.
Freud, S. (1909/1964). Analysis of phobia in a five-year-old boy. In E. A. Southwell & M. Merbaum (Eds.), Personality: Readings in theory and research (pp. 3–32). Belmont, CA: Wadsworth. (Original work published 1909).
Kotowicz, Z. (2007). The strange case of Phineas Gage. History of the Human Sciences, 20 (1), 115–131.
Rokeach, M. (1964). The three Christs of Ypsilanti: A psychological study . New York, NY: Knopf.
Stangor, C. (2011). Research methods for the behavioural sciences (4th ed.). Mountain View, CA: Cengage.
Long Descriptions
Figure 3.6 long description: There are 25 families. 24 families have an income between $44,000 and $111,000 and one family has an income of $3,800,000. The mean income is $223,960 while the median income is $73,000. [Return to Figure 3.6]
Figure 3.10 long description: Types of scatter plots.
- Positive linear, r=positive .82. The plots on the graph form a rough line that runs from lower left to upper right.
- Negative linear, r=negative .70. The plots on the graph form a rough line that runs from upper left to lower right.
- Independent, r=0.00. The plots on the graph are spread out around the centre.
- Curvilinear, r=0.00. The plots of the graph form a rough line that goes up and then down like a hill.
- Curvilinear, r=0.00. The plots on the graph for a rough line that goes down and then up like a ditch.
[Return to Figure 3.10]
Introduction to Psychology - 1st Canadian Edition Copyright © 2014 by Jennifer Walinga and Charles Stangor is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.
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Descriptive Correlational: Descriptive vs Correlational Research
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Descriptive research and Correlational research are two important types of research studies that help researchers make ambitious and measured decisions in their respective fields. Both descriptive research and correlational research are used in descriptive correlational research.
Descriptive research is defined as a research method that involves observing behavior to describe attributes objectively and systematically. A descriptive research project seeks to comprehend phenomena or groups in depth.
Correlational research , on the other hand, is a method that describes and predicts how variables are naturally related in the real world without the researcher attempting to alter them or assign causation between them.
The main objective of descriptive research is to create a snapshot of the current state of affairs, whereas correlational research helps in comparing two or more entities or variables.
What is descriptive correlational research?
Descriptive correlational research is a type of research design that tries to explain the relationship between two or more variables without making any claims about cause and effect. It includes collecting and analyzing data on at least two variables to see if there is a link between them.
In descriptive correlational research, researchers collect data to explain the variables of interest and figure out how they relate. The main goal is to give a full account of the variables and how they are related without changing them or assuming that one thing causes another.
In descriptive correlational research, researchers do not change any variables or try to find cause-and-effect connections. Instead, they just watch and measure the variables of interest and then look at the patterns and relationships that emerge from the data.
Experimental research involves the independent variable to see how it affects the dependent variable, while descriptive correlational research just describes the relationship between variables.
In descriptive correlational research, correlational research designs measure the magnitude and direction of the relationship between two or more variables, revealing their associations. At the outset creating initial equivalence between the groups or variables being compared is essential in descriptive correlational research
The independent variable occurs prior to the measurement of the measured dependent variable in descriptive correlational research. Its goal is to explain the traits or actions of a certain population or group and look at the connections between independent and dependent variables.
How are descriptive research and correlational research carried out?
Descriptive research is carried out using three methods, namely:
- Case studies – Case studies involve in-depth research and study of individuals or groups. Case studies lead to a hypothesis and widen a further scope of studying a phenomenon. However, case studies should not be used to determine cause and effect as they don’t have the capacity to make accurate predictions.
- Surveys – A survey is a set of questions that is administered to a population, also known as respondents. Surveys are a popular market research tool that helps collect meaningful insights from the respondents. To gather good quality data, a survey should have good survey questions, which should be a balanced mix of open-ended and close-ended questions .
- Naturalistic Observation – Naturalistic observations are carried out in the natural environment without disturbing the person/ object in observation. It is much like taking notes about people in a supermarket without letting them know. This leads to a greater validity of collected data because people are unaware they are being observed here. This tends to bring out their natural characteristics.
Correlational research also uses naturalistic observation to collect data. However, in addition, it uses archival data to gather information. Archival data is collected from previously conducted research of a similar nature. Archival data is collected through primary research.
In contrast to naturalistic observation, information collected through archived is straightforward. For example, counting the number of people named Jacinda in the United States using their social security number.
Descriptive Research vs Correlational Research
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Descriptive research is used to uncover new facts and the meaning of research. | Correlational research is carried out to measure two variables. | |
Descriptive research is analytical, where in-depth studies help collect information during research. | Correlational nature is mathematical in nature. A positive correlation appears coefficient to statistically measure the relationship between two variables. | |
Descriptive nature provides a knowledge base for carrying out other | This type of research is used to explore the extent to which two variables in a study are related. | |
Research was done to obtain information on the hospitality industry’s most widely used employee motivation tools. | Research has been done to know if cancer and marriage are related. |
Features of Descriptive Correlational Research
The key features of descriptive correlational research include the following:
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01. Description
The main goal, just like with descriptive research, is to describe the variables of interest thoroughly. Researchers aim to explain a certain group or event’s traits, behaviors, or attitudes.
02. Relationships
Like correlational research, descriptive correlational research looks at how two or more factors are related. It looks at how variables are connected to each other, such as how they change over time or how they are linked.
03. Quantitative analysis
Most methods for analyzing quantitative analysis data are used in descriptive correlational research. Researchers use statistical methods to study and measure the size and direction of relationships between variables.
04. No manipulation
As with correlational research, the researcher does not change or control the variables. The data is taken in its natural environment without any changes or interference.
05. Cross-sectional or longitudinal
Cross-sectional or longitudinal designs can be used for descriptive correlational research. It collects data at one point in time, while longitudinal research collects data over a long period of time to look at changes and relationships over time.
Examples of descriptive correlational research
For example, descriptive correlational research could look at the link between a person’s age and how much money they make. The researcher would take a sample of people’s ages and incomes and then look at the data to see if there is a link between the two factors.
- Example 1 : A research project is done to find out if there is a link between how long college students sleep and how well they do in school. They keep track of how many hours kids sleep each night and what their GPAs are. By studying the data, the researcher can describe how the students sleep and find out if there is a link between how long they sleep and how well they do in school.
- Example 2 : A researcher wants to know how people’s exercise habits affect their physical health if they are between the ages of 40 and 60. They take notes on things like how often and how hard you work out, your body mass index (BMI), blood pressure, and cholesterol numbers. By analyzing the data, the researcher can describe the participants’ exercise habits and physical health and look for any links between these factors.
- Example 3 : Let’s say a researcher wants to find out if college students who work out feel less stressed. Using a poll, the researcher finds out how many hours students spend exercising each week and how stressed they feel. By looking at the data, the researcher may find that there is a moderate negative correlation between exercise and stress levels. This means that as exercise grows, stress levels tend to go down.
Descriptive correlational research is a good way to learn about the characteristics of a population or group and the relationships between its different parts. It lets researchers describe variables in detail and look into their relationships without suggesting that one variable caused another.
Descriptive correlational research gives useful insights and can be used as a starting point for more research or to come up with hypotheses. It’s important to be aware of the problems with this type of study, such as the fact that it can’t show cause and effect and relies on cross-sectional data.
Still, descriptive correlational research helps us understand things and makes making decisions in many areas easier.
QuestionPro is a very useful tool for descriptive correlational research. Its many features and easy-to-use interface help researchers collect and study data quickly, giving them a better understanding of the characteristics and relationships between variables in a certain population or group.
The different kinds of questions, analytical research tools, and reporting features on the software improve the research process and help researchers come up with useful results. QuestionPro makes it easier to do descriptive correlational research, which makes it a useful tool for learning important things and making decisions in many fields.
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2.2 Psychologists Use Descriptive, Correlational, and Experimental Research Designs to Understand Behavior
Learning objectives.
- Differentiate the goals of descriptive, correlational, and experimental research designs and explain the advantages and disadvantages of each.
- Explain the goals of descriptive research and the statistical techniques used to interpret it.
- Summarize the uses of correlational research and describe why correlational research cannot be used to infer causality.
- Review the procedures of experimental research and explain how it can be used to draw causal inferences.
Psychologists agree that if their ideas and theories about human behavior are to be taken seriously, they must be backed up by data. However, the research of different psychologists is designed with different goals in mind, and the different goals require different approaches. These varying approaches, summarized in Table 2.2 “Characteristics of the Three Research Designs” , are known as research designs . A research design is the specific method a researcher uses to collect, analyze, and interpret data . Psychologists use three major types of research designs in their research, and each provides an essential avenue for scientific investigation. Descriptive research is research designed to provide a snapshot of the current state of affairs . Correlational research is research designed to discover relationships among variables and to allow the prediction of future events from present knowledge . Experimental research is research in which initial equivalence among research participants in more than one group is created, followed by a manipulation of a given experience for these groups and a measurement of the influence of the manipulation . Each of the three research designs varies according to its strengths and limitations, and it is important to understand how each differs.
Table 2.2 Characteristics of the Three Research Designs
Research design | Goal | Advantages | Disadvantages |
---|---|---|---|
Descriptive | To create a snapshot of the current state of affairs | Provides a relatively complete picture of what is occurring at a given time. Allows the development of questions for further study. | Does not assess relationships among variables. May be unethical if participants do not know they are being observed. |
Correlational | To assess the relationships between and among two or more variables | Allows testing of expected relationships between and among variables and the making of predictions. Can assess these relationships in everyday life events. | Cannot be used to draw inferences about the causal relationships between and among the variables. |
Experimental | To assess the causal impact of one or more experimental manipulations on a dependent variable | Allows drawing of conclusions about the causal relationships among variables. | Cannot experimentally manipulate many important variables. May be expensive and time consuming. |
There are three major research designs used by psychologists, and each has its own advantages and disadvantages. |
Stangor, C. (2011). Research methods for the behavioral sciences (4th ed.). Mountain View, CA: Cengage.
Descriptive Research: Assessing the Current State of Affairs
Descriptive research is designed to create a snapshot of the current thoughts, feelings, or behavior of individuals. This section reviews three types of descriptive research: case studies , surveys , and naturalistic observation .
Sometimes the data in a descriptive research project are based on only a small set of individuals, often only one person or a single small group. These research designs are known as case studies — descriptive records of one or more individual’s experiences and behavior . Sometimes case studies involve ordinary individuals, as when developmental psychologist Jean Piaget used his observation of his own children to develop his stage theory of cognitive development. More frequently, case studies are conducted on individuals who have unusual or abnormal experiences or characteristics or who find themselves in particularly difficult or stressful situations. The assumption is that by carefully studying individuals who are socially marginal, who are experiencing unusual situations, or who are going through a difficult phase in their lives, we can learn something about human nature.
Sigmund Freud was a master of using the psychological difficulties of individuals to draw conclusions about basic psychological processes. Freud wrote case studies of some of his most interesting patients and used these careful examinations to develop his important theories of personality. One classic example is Freud’s description of “Little Hans,” a child whose fear of horses the psychoanalyst interpreted in terms of repressed sexual impulses and the Oedipus complex (Freud (1909/1964).
![descriptive correlational or experimental research Three news papers on a table (The Daily Telegraph, The Guardian, and The Times), all predicting Obama has the edge in the early polls.](https://open.lib.umn.edu/app/uploads/sites/2/2015/08/3009105822_b96dc2a9bc_z.jpg)
Political polls reported in newspapers and on the Internet are descriptive research designs that provide snapshots of the likely voting behavior of a population.
Another well-known case study is Phineas Gage, a man whose thoughts and emotions were extensively studied by cognitive psychologists after a railroad spike was blasted through his skull in an accident. Although there is question about the interpretation of this case study (Kotowicz, 2007), it did provide early evidence that the brain’s frontal lobe is involved in emotion and morality (Damasio et al., 2005). An interesting example of a case study in clinical psychology is described by Rokeach (1964), who investigated in detail the beliefs and interactions among three patients with schizophrenia, all of whom were convinced they were Jesus Christ.
In other cases the data from descriptive research projects come in the form of a survey — a measure administered through either an interview or a written questionnaire to get a picture of the beliefs or behaviors of a sample of people of interest . The people chosen to participate in the research (known as the sample ) are selected to be representative of all the people that the researcher wishes to know about (the population ). In election polls, for instance, a sample is taken from the population of all “likely voters” in the upcoming elections.
The results of surveys may sometimes be rather mundane, such as “Nine out of ten doctors prefer Tymenocin,” or “The median income in Montgomery County is $36,712.” Yet other times (particularly in discussions of social behavior), the results can be shocking: “More than 40,000 people are killed by gunfire in the United States every year,” or “More than 60% of women between the ages of 50 and 60 suffer from depression.” Descriptive research is frequently used by psychologists to get an estimate of the prevalence (or incidence ) of psychological disorders.
A final type of descriptive research—known as naturalistic observation —is research based on the observation of everyday events . For instance, a developmental psychologist who watches children on a playground and describes what they say to each other while they play is conducting descriptive research, as is a biopsychologist who observes animals in their natural habitats. One example of observational research involves a systematic procedure known as the strange situation , used to get a picture of how adults and young children interact. The data that are collected in the strange situation are systematically coded in a coding sheet such as that shown in Table 2.3 “Sample Coding Form Used to Assess Child’s and Mother’s Behavior in the Strange Situation” .
Table 2.3 Sample Coding Form Used to Assess Child’s and Mother’s Behavior in the Strange Situation
Coder name: | ||||
---|---|---|---|---|
Mother and baby play alone | ||||
Mother puts baby down | ||||
Stranger enters room | ||||
Mother leaves room; stranger plays with baby | ||||
Mother reenters, greets and may comfort baby, then leaves again | ||||
Stranger tries to play with baby | ||||
Mother reenters and picks up baby | ||||
The baby moves toward, grasps, or climbs on the adult. | ||||
The baby resists being put down by the adult by crying or trying to climb back up. | ||||
The baby pushes, hits, or squirms to be put down from the adult’s arms. | ||||
The baby turns away or moves away from the adult. | ||||
This table represents a sample coding sheet from an episode of the “strange situation,” in which an infant (usually about 1 year old) is observed playing in a room with two adults—the child’s mother and a stranger. Each of the four coding categories is scored by the coder from 1 (the baby makes no effort to engage in the behavior) to 7 (the baby makes a significant effort to engage in the behavior). More information about the meaning of the coding can be found in Ainsworth, Blehar, Waters, and Wall (1978). |
The results of descriptive research projects are analyzed using descriptive statistics — numbers that summarize the distribution of scores on a measured variable . Most variables have distributions similar to that shown in Figure 2.5 “Height Distribution” , where most of the scores are located near the center of the distribution, and the distribution is symmetrical and bell-shaped. A data distribution that is shaped like a bell is known as a normal distribution .
Table 2.4 Height and Family Income for 25 Students
Student name | Height in inches | Family income in dollars |
---|---|---|
Lauren | 62 | 48,000 |
Courtnie | 62 | 57,000 |
Leslie | 63 | 93,000 |
Renee | 64 | 107,000 |
Katherine | 64 | 110,000 |
Jordan | 65 | 93,000 |
Rabiah | 66 | 46,000 |
Alina | 66 | 84,000 |
Young Su | 67 | 68,000 |
Martin | 67 | 49,000 |
Hanzhu | 67 | 73,000 |
Caitlin | 67 | 3,800,000 |
Steven | 67 | 107,000 |
Emily | 67 | 64,000 |
Amy | 68 | 67,000 |
Jonathan | 68 | 51,000 |
Julian | 68 | 48,000 |
Alissa | 68 | 93,000 |
Christine | 69 | 93,000 |
Candace | 69 | 111,000 |
Xiaohua | 69 | 56,000 |
Charlie | 70 | 94,000 |
Timothy | 71 | 73,000 |
Ariane | 72 | 70,000 |
Logan | 72 | 44,000 |
Figure 2.5 Height Distribution
![descriptive correlational or experimental research The distribution of the heights of the students in a class will form a normal distribution. In this sample the mean (M) = 67.12 and the standard deviation (s) = 2.74.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/ab413c6115eb127a1a39c9d2ead185a1.jpg)
The distribution of the heights of the students in a class will form a normal distribution. In this sample the mean ( M ) = 67.12 and the standard deviation ( s ) = 2.74.
A distribution can be described in terms of its central tendency —that is, the point in the distribution around which the data are centered—and its dispersion , or spread. The arithmetic average, or arithmetic mean , is the most commonly used measure of central tendency . It is computed by calculating the sum of all the scores of the variable and dividing this sum by the number of participants in the distribution (denoted by the letter N ). In the data presented in Figure 2.5 “Height Distribution” , the mean height of the students is 67.12 inches. The sample mean is usually indicated by the letter M .
In some cases, however, the data distribution is not symmetrical. This occurs when there are one or more extreme scores (known as outliers ) at one end of the distribution. Consider, for instance, the variable of family income (see Figure 2.6 “Family Income Distribution” ), which includes an outlier (a value of $3,800,000). In this case the mean is not a good measure of central tendency. Although it appears from Figure 2.6 “Family Income Distribution” that the central tendency of the family income variable should be around $70,000, the mean family income is actually $223,960. The single very extreme income has a disproportionate impact on the mean, resulting in a value that does not well represent the central tendency.
The median is used as an alternative measure of central tendency when distributions are not symmetrical. The median is the score in the center of the distribution, meaning that 50% of the scores are greater than the median and 50% of the scores are less than the median . In our case, the median household income ($73,000) is a much better indication of central tendency than is the mean household income ($223,960).
Figure 2.6 Family Income Distribution
![descriptive correlational or experimental research The distribution of family incomes is likely to be nonsymmetrical because some incomes can be very large in comparison to most incomes. In this case the median or the mode is a better indicator of central tendency than is the mean.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/b8212ba31f9f7f0c8b9a84f41278e261.jpg)
The distribution of family incomes is likely to be nonsymmetrical because some incomes can be very large in comparison to most incomes. In this case the median or the mode is a better indicator of central tendency than is the mean.
A final measure of central tendency, known as the mode , represents the value that occurs most frequently in the distribution . You can see from Figure 2.6 “Family Income Distribution” that the mode for the family income variable is $93,000 (it occurs four times).
In addition to summarizing the central tendency of a distribution, descriptive statistics convey information about how the scores of the variable are spread around the central tendency. Dispersion refers to the extent to which the scores are all tightly clustered around the central tendency, like this:
![descriptive correlational or experimental research Graph of a tightly clustered central tendency.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/ef86c2367b52d7d44600852d0e9a4147.jpg)
Or they may be more spread out away from it, like this:
![descriptive correlational or experimental research Graph of a more spread out central tendency.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/a32be157e342fd87849eef399b8b0dfa.jpg)
One simple measure of dispersion is to find the largest (the maximum ) and the smallest (the minimum ) observed values of the variable and to compute the range of the variable as the maximum observed score minus the minimum observed score. You can check that the range of the height variable in Figure 2.5 “Height Distribution” is 72 – 62 = 10. The standard deviation , symbolized as s , is the most commonly used measure of dispersion . Distributions with a larger standard deviation have more spread. The standard deviation of the height variable is s = 2.74, and the standard deviation of the family income variable is s = $745,337.
An advantage of descriptive research is that it attempts to capture the complexity of everyday behavior. Case studies provide detailed information about a single person or a small group of people, surveys capture the thoughts or reported behaviors of a large population of people, and naturalistic observation objectively records the behavior of people or animals as it occurs naturally. Thus descriptive research is used to provide a relatively complete understanding of what is currently happening.
Despite these advantages, descriptive research has a distinct disadvantage in that, although it allows us to get an idea of what is currently happening, it is usually limited to static pictures. Although descriptions of particular experiences may be interesting, they are not always transferable to other individuals in other situations, nor do they tell us exactly why specific behaviors or events occurred. For instance, descriptions of individuals who have suffered a stressful event, such as a war or an earthquake, can be used to understand the individuals’ reactions to the event but cannot tell us anything about the long-term effects of the stress. And because there is no comparison group that did not experience the stressful situation, we cannot know what these individuals would be like if they hadn’t had the stressful experience.
Correlational Research: Seeking Relationships Among Variables
In contrast to descriptive research, which is designed primarily to provide static pictures, correlational research involves the measurement of two or more relevant variables and an assessment of the relationship between or among those variables. For instance, the variables of height and weight are systematically related (correlated) because taller people generally weigh more than shorter people. In the same way, study time and memory errors are also related, because the more time a person is given to study a list of words, the fewer errors he or she will make. When there are two variables in the research design, one of them is called the predictor variable and the other the outcome variable . The research design can be visualized like this, where the curved arrow represents the expected correlation between the two variables:
Figure 2.2.2
![descriptive correlational or experimental research Left: Predictor variable, Right: Outcome variable.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/3e9e4cb450e16b5577f7786ac25fcd86.jpg)
One way of organizing the data from a correlational study with two variables is to graph the values of each of the measured variables using a scatter plot . As you can see in Figure 2.10 “Examples of Scatter Plots” , a scatter plot is a visual image of the relationship between two variables . A point is plotted for each individual at the intersection of his or her scores for the two variables. When the association between the variables on the scatter plot can be easily approximated with a straight line, as in parts (a) and (b) of Figure 2.10 “Examples of Scatter Plots” , the variables are said to have a linear relationship .
When the straight line indicates that individuals who have above-average values for one variable also tend to have above-average values for the other variable, as in part (a), the relationship is said to be positive linear . Examples of positive linear relationships include those between height and weight, between education and income, and between age and mathematical abilities in children. In each case people who score higher on one of the variables also tend to score higher on the other variable. Negative linear relationships , in contrast, as shown in part (b), occur when above-average values for one variable tend to be associated with below-average values for the other variable. Examples of negative linear relationships include those between the age of a child and the number of diapers the child uses, and between practice on and errors made on a learning task. In these cases people who score higher on one of the variables tend to score lower on the other variable.
Relationships between variables that cannot be described with a straight line are known as nonlinear relationships . Part (c) of Figure 2.10 “Examples of Scatter Plots” shows a common pattern in which the distribution of the points is essentially random. In this case there is no relationship at all between the two variables, and they are said to be independent . Parts (d) and (e) of Figure 2.10 “Examples of Scatter Plots” show patterns of association in which, although there is an association, the points are not well described by a single straight line. For instance, part (d) shows the type of relationship that frequently occurs between anxiety and performance. Increases in anxiety from low to moderate levels are associated with performance increases, whereas increases in anxiety from moderate to high levels are associated with decreases in performance. Relationships that change in direction and thus are not described by a single straight line are called curvilinear relationships .
Figure 2.10 Examples of Scatter Plots
![descriptive correlational or experimental research Some examples of relationships between two variables as shown in scatter plots. Note that the Pearson correlation coefficient (r) between variables that have curvilinear relationships will likely be close to zero.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/7d02dd43cd07dbf3c306b04414fc33a5.jpg)
Some examples of relationships between two variables as shown in scatter plots. Note that the Pearson correlation coefficient ( r ) between variables that have curvilinear relationships will likely be close to zero.
Adapted from Stangor, C. (2011). Research methods for the behavioral sciences (4th ed.). Mountain View, CA: Cengage.
The most common statistical measure of the strength of linear relationships among variables is the Pearson correlation coefficient , which is symbolized by the letter r . The value of the correlation coefficient ranges from r = –1.00 to r = +1.00. The direction of the linear relationship is indicated by the sign of the correlation coefficient. Positive values of r (such as r = .54 or r = .67) indicate that the relationship is positive linear (i.e., the pattern of the dots on the scatter plot runs from the lower left to the upper right), whereas negative values of r (such as r = –.30 or r = –.72) indicate negative linear relationships (i.e., the dots run from the upper left to the lower right). The strength of the linear relationship is indexed by the distance of the correlation coefficient from zero (its absolute value). For instance, r = –.54 is a stronger relationship than r = .30, and r = .72 is a stronger relationship than r = –.57. Because the Pearson correlation coefficient only measures linear relationships, variables that have curvilinear relationships are not well described by r , and the observed correlation will be close to zero.
It is also possible to study relationships among more than two measures at the same time. A research design in which more than one predictor variable is used to predict a single outcome variable is analyzed through multiple regression (Aiken & West, 1991). Multiple regression is a statistical technique, based on correlation coefficients among variables, that allows predicting a single outcome variable from more than one predictor variable . For instance, Figure 2.11 “Prediction of Job Performance From Three Predictor Variables” shows a multiple regression analysis in which three predictor variables are used to predict a single outcome. The use of multiple regression analysis shows an important advantage of correlational research designs—they can be used to make predictions about a person’s likely score on an outcome variable (e.g., job performance) based on knowledge of other variables.
Figure 2.11 Prediction of Job Performance From Three Predictor Variables
![descriptive correlational or experimental research Multiple regression allows scientists to predict the scores on a single outcome variable using more than one predictor variable.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/464b865cd2cfc7379c21031b32df5651.jpg)
Multiple regression allows scientists to predict the scores on a single outcome variable using more than one predictor variable.
An important limitation of correlational research designs is that they cannot be used to draw conclusions about the causal relationships among the measured variables. Consider, for instance, a researcher who has hypothesized that viewing violent behavior will cause increased aggressive play in children. He has collected, from a sample of fourth-grade children, a measure of how many violent television shows each child views during the week, as well as a measure of how aggressively each child plays on the school playground. From his collected data, the researcher discovers a positive correlation between the two measured variables.
Although this positive correlation appears to support the researcher’s hypothesis, it cannot be taken to indicate that viewing violent television causes aggressive behavior. Although the researcher is tempted to assume that viewing violent television causes aggressive play,
![descriptive correlational or experimental research Viewing violent TV may lead to aggressive play.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/e8907bc26020d44b8ec4fa0b3b7d6977.jpg)
there are other possibilities. One alternate possibility is that the causal direction is exactly opposite from what has been hypothesized. Perhaps children who have behaved aggressively at school develop residual excitement that leads them to want to watch violent television shows at home:
![descriptive correlational or experimental research Or perhaps aggressive play leads to viewing violent TV.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/e68943a11c28a61179fd09121f0bc921.jpg)
Although this possibility may seem less likely, there is no way to rule out the possibility of such reverse causation on the basis of this observed correlation. It is also possible that both causal directions are operating and that the two variables cause each other:
![descriptive correlational or experimental research One may cause the other, but there could be a common-causal variable.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/3f0d249134c13cc5d21f7f6f4d784c78.jpg)
Still another possible explanation for the observed correlation is that it has been produced by the presence of a common-causal variable (also known as a third variable ). A common-causal variable is a variable that is not part of the research hypothesis but that causes both the predictor and the outcome variable and thus produces the observed correlation between them . In our example a potential common-causal variable is the discipline style of the children’s parents. Parents who use a harsh and punitive discipline style may produce children who both like to watch violent television and who behave aggressively in comparison to children whose parents use less harsh discipline:
![descriptive correlational or experimental research An example: Parents' discipline style may cause viewing violent TV, and it may also cause aggressive play.](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/675c2fd95172ea21e05ea1870c1f0927.jpg)
In this case, television viewing and aggressive play would be positively correlated (as indicated by the curved arrow between them), even though neither one caused the other but they were both caused by the discipline style of the parents (the straight arrows). When the predictor and outcome variables are both caused by a common-causal variable, the observed relationship between them is said to be spurious . A spurious relationship is a relationship between two variables in which a common-causal variable produces and “explains away” the relationship . If effects of the common-causal variable were taken away, or controlled for, the relationship between the predictor and outcome variables would disappear. In the example the relationship between aggression and television viewing might be spurious because by controlling for the effect of the parents’ disciplining style, the relationship between television viewing and aggressive behavior might go away.
Common-causal variables in correlational research designs can be thought of as “mystery” variables because, as they have not been measured, their presence and identity are usually unknown to the researcher. Since it is not possible to measure every variable that could cause both the predictor and outcome variables, the existence of an unknown common-causal variable is always a possibility. For this reason, we are left with the basic limitation of correlational research: Correlation does not demonstrate causation. It is important that when you read about correlational research projects, you keep in mind the possibility of spurious relationships, and be sure to interpret the findings appropriately. Although correlational research is sometimes reported as demonstrating causality without any mention being made of the possibility of reverse causation or common-causal variables, informed consumers of research, like you, are aware of these interpretational problems.
In sum, correlational research designs have both strengths and limitations. One strength is that they can be used when experimental research is not possible because the predictor variables cannot be manipulated. Correlational designs also have the advantage of allowing the researcher to study behavior as it occurs in everyday life. And we can also use correlational designs to make predictions—for instance, to predict from the scores on their battery of tests the success of job trainees during a training session. But we cannot use such correlational information to determine whether the training caused better job performance. For that, researchers rely on experiments.
![](http://sektorel.online/777/templates/cheerup/res/banner1.gif)
Experimental Research: Understanding the Causes of Behavior
The goal of experimental research design is to provide more definitive conclusions about the causal relationships among the variables in the research hypothesis than is available from correlational designs. In an experimental research design, the variables of interest are called the independent variable (or variables ) and the dependent variable . The independent variable in an experiment is the causing variable that is created (manipulated) by the experimenter . The dependent variable in an experiment is a measured variable that is expected to be influenced by the experimental manipulation . The research hypothesis suggests that the manipulated independent variable or variables will cause changes in the measured dependent variables. We can diagram the research hypothesis by using an arrow that points in one direction. This demonstrates the expected direction of causality:
Figure 2.2.3
![descriptive correlational or experimental research Viewing violence (independent variable) and aggressive behavior (dependent variable).](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/a41e39077cc5b3be3d74924bdcc43066.jpg)
Research Focus: Video Games and Aggression
Consider an experiment conducted by Anderson and Dill (2000). The study was designed to test the hypothesis that viewing violent video games would increase aggressive behavior. In this research, male and female undergraduates from Iowa State University were given a chance to play with either a violent video game (Wolfenstein 3D) or a nonviolent video game (Myst). During the experimental session, the participants played their assigned video games for 15 minutes. Then, after the play, each participant played a competitive game with an opponent in which the participant could deliver blasts of white noise through the earphones of the opponent. The operational definition of the dependent variable (aggressive behavior) was the level and duration of noise delivered to the opponent. The design of the experiment is shown in Figure 2.17 “An Experimental Research Design” .
Figure 2.17 An Experimental Research Design
![descriptive correlational or experimental research Two advantages of the experimental research design are (1) the assurance that the independent variable (also known as the experimental manipulation) occurs prior to the measured dependent variable, and (2) the creation of initial equivalence between the conditions of the experiment (in this case by using random assignment to conditions).](https://open.lib.umn.edu/app/uploads/sites/2/2015/01/23f54cb6e62facaacf8c4aaff5c82e26.jpg)
Two advantages of the experimental research design are (1) the assurance that the independent variable (also known as the experimental manipulation) occurs prior to the measured dependent variable, and (2) the creation of initial equivalence between the conditions of the experiment (in this case by using random assignment to conditions).
Experimental designs have two very nice features. For one, they guarantee that the independent variable occurs prior to the measurement of the dependent variable. This eliminates the possibility of reverse causation. Second, the influence of common-causal variables is controlled, and thus eliminated, by creating initial equivalence among the participants in each of the experimental conditions before the manipulation occurs.
The most common method of creating equivalence among the experimental conditions is through random assignment to conditions , a procedure in which the condition that each participant is assigned to is determined through a random process, such as drawing numbers out of an envelope or using a random number table . Anderson and Dill first randomly assigned about 100 participants to each of their two groups (Group A and Group B). Because they used random assignment to conditions, they could be confident that, before the experimental manipulation occurred, the students in Group A were, on average, equivalent to the students in Group B on every possible variable, including variables that are likely to be related to aggression, such as parental discipline style, peer relationships, hormone levels, diet—and in fact everything else.
Then, after they had created initial equivalence, Anderson and Dill created the experimental manipulation—they had the participants in Group A play the violent game and the participants in Group B play the nonviolent game. Then they compared the dependent variable (the white noise blasts) between the two groups, finding that the students who had viewed the violent video game gave significantly longer noise blasts than did the students who had played the nonviolent game.
Anderson and Dill had from the outset created initial equivalence between the groups. This initial equivalence allowed them to observe differences in the white noise levels between the two groups after the experimental manipulation, leading to the conclusion that it was the independent variable (and not some other variable) that caused these differences. The idea is that the only thing that was different between the students in the two groups was the video game they had played.
Despite the advantage of determining causation, experiments do have limitations. One is that they are often conducted in laboratory situations rather than in the everyday lives of people. Therefore, we do not know whether results that we find in a laboratory setting will necessarily hold up in everyday life. Second, and more important, is that some of the most interesting and key social variables cannot be experimentally manipulated. If we want to study the influence of the size of a mob on the destructiveness of its behavior, or to compare the personality characteristics of people who join suicide cults with those of people who do not join such cults, these relationships must be assessed using correlational designs, because it is simply not possible to experimentally manipulate these variables.
Key Takeaways
- Descriptive, correlational, and experimental research designs are used to collect and analyze data.
- Descriptive designs include case studies, surveys, and naturalistic observation. The goal of these designs is to get a picture of the current thoughts, feelings, or behaviors in a given group of people. Descriptive research is summarized using descriptive statistics.
- Correlational research designs measure two or more relevant variables and assess a relationship between or among them. The variables may be presented on a scatter plot to visually show the relationships. The Pearson Correlation Coefficient ( r ) is a measure of the strength of linear relationship between two variables.
- Common-causal variables may cause both the predictor and outcome variable in a correlational design, producing a spurious relationship. The possibility of common-causal variables makes it impossible to draw causal conclusions from correlational research designs.
- Experimental research involves the manipulation of an independent variable and the measurement of a dependent variable. Random assignment to conditions is normally used to create initial equivalence between the groups, allowing researchers to draw causal conclusions.
Exercises and Critical Thinking
- There is a negative correlation between the row that a student sits in in a large class (when the rows are numbered from front to back) and his or her final grade in the class. Do you think this represents a causal relationship or a spurious relationship, and why?
- Think of two variables (other than those mentioned in this book) that are likely to be correlated, but in which the correlation is probably spurious. What is the likely common-causal variable that is producing the relationship?
- Imagine a researcher wants to test the hypothesis that participating in psychotherapy will cause a decrease in reported anxiety. Describe the type of research design the investigator might use to draw this conclusion. What would be the independent and dependent variables in the research?
Aiken, L., & West, S. (1991). Multiple regression: Testing and interpreting interactions . Newbury Park, CA: Sage.
Ainsworth, M. S., Blehar, M. C., Waters, E., & Wall, S. (1978). Patterns of attachment: A psychological study of the strange situation . Hillsdale, NJ: Lawrence Erlbaum Associates.
Anderson, C. A., & Dill, K. E. (2000). Video games and aggressive thoughts, feelings, and behavior in the laboratory and in life. Journal of Personality and Social Psychology, 78 (4), 772–790.
Damasio, H., Grabowski, T., Frank, R., Galaburda, A. M., Damasio, A. R., Cacioppo, J. T., & Berntson, G. G. (2005). The return of Phineas Gage: Clues about the brain from the skull of a famous patient. In Social neuroscience: Key readings. (pp. 21–28). New York, NY: Psychology Press.
Freud, S. (1964). Analysis of phobia in a five-year-old boy. In E. A. Southwell & M. Merbaum (Eds.), Personality: Readings in theory and research (pp. 3–32). Belmont, CA: Wadsworth. (Original work published 1909)
Kotowicz, Z. (2007). The strange case of Phineas Gage. History of the Human Sciences, 20 (1), 115–131.
Rokeach, M. (1964). The three Christs of Ypsilanti: A psychological study . New York, NY: Knopf.
Introduction to Psychology Copyright © 2015 by University of Minnesota is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.
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Methodology
- Descriptive Research | Definition, Types, Methods & Examples
Descriptive Research | Definition, Types, Methods & Examples
Published on May 15, 2019 by Shona McCombes . Revised on June 22, 2023.
Descriptive research aims to accurately and systematically describe a population, situation or phenomenon. It can answer what , where , when and how questions , but not why questions.
A descriptive research design can use a wide variety of research methods to investigate one or more variables . Unlike in experimental research , the researcher does not control or manipulate any of the variables, but only observes and measures them.
Table of contents
When to use a descriptive research design, descriptive research methods, other interesting articles.
Descriptive research is an appropriate choice when the research aim is to identify characteristics, frequencies, trends, and categories.
It is useful when not much is known yet about the topic or problem. Before you can research why something happens, you need to understand how, when and where it happens.
Descriptive research question examples
- How has the Amsterdam housing market changed over the past 20 years?
- Do customers of company X prefer product X or product Y?
- What are the main genetic, behavioural and morphological differences between European wildcats and domestic cats?
- What are the most popular online news sources among under-18s?
- How prevalent is disease A in population B?
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Descriptive research is usually defined as a type of quantitative research , though qualitative research can also be used for descriptive purposes. The research design should be carefully developed to ensure that the results are valid and reliable .
Survey research allows you to gather large volumes of data that can be analyzed for frequencies, averages and patterns. Common uses of surveys include:
- Describing the demographics of a country or region
- Gauging public opinion on political and social topics
- Evaluating satisfaction with a company’s products or an organization’s services
Observations
Observations allow you to gather data on behaviours and phenomena without having to rely on the honesty and accuracy of respondents. This method is often used by psychological, social and market researchers to understand how people act in real-life situations.
Observation of physical entities and phenomena is also an important part of research in the natural sciences. Before you can develop testable hypotheses , models or theories, it’s necessary to observe and systematically describe the subject under investigation.
Case studies
A case study can be used to describe the characteristics of a specific subject (such as a person, group, event or organization). Instead of gathering a large volume of data to identify patterns across time or location, case studies gather detailed data to identify the characteristics of a narrowly defined subject.
Rather than aiming to describe generalizable facts, case studies often focus on unusual or interesting cases that challenge assumptions, add complexity, or reveal something new about a research problem .
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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Observational Study Designs: Synopsis for Selecting an Appropriate Study Design
Assad a rezigalla.
1 Department of Basic Medical Sciences, College of Medicine, University of Bisha, Bisha, SAU
The selection of a study design is the most critical step in the research methodology. Crucial factors should be considered during the selection of the study design, which is the formulated research question, as well as the method of participant selection. Different study designs can be applied to the same research question(s). Research designs are classified as qualitative, quantitative, and mixed design. Observational design occupies the middle and lower parts of the hierarchy of evidence-based pyramid. The observational design is subdivided into descriptive, including cross-sectional, case report or case series, and correlational, and analytic which includes cross-section, case-control, and cohort studies. Each research design has its uses and points of strength and limitations. The aim of this article to provide a simplified approach for the selection of descriptive study design.
Introduction and background
A research design is defined as the “set up to decide on, among other issues, how to collect further data, analyze and interpret them, and finally, to provide an answer to the question” [ 1 ]. The primary objective of a research design is to guarantee that the collected evidence allows the answering of the initial question(s) as clearly as possible [ 2 ]. Various study designs have been described in the literature [ 1 - 3 ]. Each of them deals with the specific type of research or research questions and has points of strength and weakness. Broadly, research designs are classified into qualitative and quantitative research and mixed methods [ 3 ]. The quantitative study design is subdivided into descriptive versus analytical study designs or as observational versus interventional (Figure (Figure1). 1 ). Descriptive designs occupy the middle and lower parts of the hierarchy of evidence-based medicine pyramid. Study designs are organized in a hierarchy beginning from the basic "case report" to the highly valued "randomised clinical trial" [ 4 - 5 ].
![Click on image to zoom An external file that holds a picture, illustration, etc.
Object name is cureus-0012-00000006692-i01.jpg](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6970097/bin/cureus-0012-00000006692-i01.jpg)
Case report
The case report describes an individual case or cases in their natural settings. Also, it describes unrecognized syndromes or variants, abnormal findings or outcomes, or association between risk factors and disease. It is the lowest level and the first line of evidence and usually deals with the newly emerging issues and ideas (Table (Table1) 1 ) [ 4 , 6 - 10 ].
Case Report Design | |
Strengths [ , - ] | Limitations [ , ] |
Identification of new, abnormal, or variant presentation of diseases. | Lack of generalizability and implications. |
Have significant educational value. | Uncontrolled. |
Help in generating a hypothesis. | Selection bias. |
Researching rare or uncommon disorders. | No epidemiological indices (parameters). |
In-depth narrative case studies. | Over-interpretation. |
Flexible structure. | Confidentiality. |
Causes may have other explanations. |
Case series
A case series is a report on data from a subject group (multiple patients) without control [ 6 , 11 - 12 ]. Commonly, this design is used for the illustration of novel, unusual, or atypical features identified in medical practice [ 6 ]. The investigator is governed by the availability and accuracy of the records, which can cause biases [ 13 - 14 ]. Bias in a case series can be decreased through consecutive patient enrollment and predefined inclusion and exclusion criteria, explicit specification of study duration, and enrollment of participants (Table 2 ) [ 11 - 12 ].
Case Series | |
Strengths [ , - ] | Limitations [ , - ] |
Educational. | Selection bias. |
It described the outcomes of novel treatments. | Lack of control. |
The gained information can be used to generate hypotheses. | Difficult to compare different cases. |
Provide strong evidence with multiple cases. | The result may not be generalized. |
Helpful in refining new techniques or treatment protocols. | Immediate follow-up. |
Identify the rare manifestations of a disease or drug. | Have a lower position on the hierarchy of evidence. |
Feasible study designs. |
Correlational study design
Correlational studies (ecologic studies) explore the statistical relationships between the outcome of interest in population and estimate the exposures. It deals with the community rather than in individual cases. The correlational study design can compare two or more relevant variables and reports the association between them without controlling the variables. The aim of correlational study design or research is to uncover any types of systematic relationships between the studied variables. Ecological studies are often used to measure the prevalence and incidence of disease, mainly when the disease is rare. The populations compared can be defined in several ways, such as geographical, time trends, migrants, longitudinal, occupation, and social class. It should be considered that in ecological studies, the results are presented at the population (group) level rather than individuals. Ecological studies do not provide information about the degree or extent of exposure or outcome of interest for particular individuals within the study group (Table 3 ) [ 7 , 15 - 16 ]. For example, we do not know whether those individuals who died in the study group under observation had higher exposure than those remained alive.
Correlational study design | |
Strengths [ - ] | Limitations [ - ] |
Quick and easy. | Correlations do not equal causation. |
Describes the strength of relationships. | Correlations can be misused. |
It is used to assess behavior. | Cannot be used to identify causal relationships |
Predictor variables cannot be manipulated. | It cannot provide certain information. |
Uses of data records. |
Cross-sectional study design
The cross-sectional study examines the association between exposures and outcomes on a snap of time. The assessed associations are guided by sound hypotheses and seen as hypothesis-generating [ 17 ]. This design can be descriptive (when dealing with prevalence or survey) or analytic (when comparing groups) [ 17 - 18 ]. The selection of participants in a cross-sectional study design depends on the predefined inclusion and exclusion criteria [ 18 - 19 ]. This method of selection limits randomization (Table 4 ).
Cross-sectional Study Design | |
Strengths of [ , - ] | Limitations [ , - ] |
Fast and inexpensive. | Difficult to derive causal relationships. |
Useful for planning monitoring and evaluation of public health. | Prone to certain types of biases. |
Efficient in studying rare diseases. | The response rate is critical. |
There are seldom ethical difficulties. | The temporality of the design. |
It can assess multiple outcomes. | No clear demarcation between exposure and effect. |
Population-based surveys. | |
Estimation of prevalence. | |
Calculation of odds ratio. | |
The baseline for a cohort study. |
Case-control study
A case-control study is an observational analytic retrospective study design [ 12 ]. It starts with the outcome of interest (referred to as cases) and looks back in time for exposures that likely caused the outcome of interest [ 13 , 20 ]. This design compares two groups of participants - those with the outcome of interest and the matched control [ 12 ]. The controls should match the group of interest in most of the aspects, except for the outcome of interest [ 18 ]. The controls should be selected from the same localization or setting of the cases [ 13 , 21 - 22 ]. Case-control studies can determine the relative importance of a predictor variable about the presence or absence of the disease (Table (Table5 5 ).
Case-control Study Design | |
Strengths [ , - ] | Limitations [ , - ] |
Relatively fast in conduction in comparison with prospective cohort studies. | Not useful for rare exposures. |
Comparatively, needs few participants and fewer resources. | Cannot estimate the incidence. |
Useful for testing hypotheses. | Affect by observation and recall bias. |
Useful in studying multiple exposures in the same outcome. | |
Can study the association of risk factors and outcomes in outbreak investigations. | |
It can generate much information from relatively few participants with unusual cases. | |
Feasible in diseases with a long latent period. |
Cohort study design
The cohort study design is classified as an observational analytic study design. This design compares two groups, with exposure of interest and control one [ 12 , 18 , 22 - 24 ].
Cohort design starts with exposure of interest comparing them to non-exposed participants at the time of study initiation [ 18 , 22 , 24 ]. The non-exposed serve as external control. A cohort design can be either prospective [ 18 ] or retrospective [ 12 , 20 , 24 - 25 ]. In prospective cohort studies, the investigator measures a variety of variables that might be a risk factor or relevant to the development of the outcome of interest. Over time, the participants are observed to detect whether they develop the outcome of interest or not. In this case, the participants who do not develop the outcome of interest can act as internal controls. Retrospective cohort studies use data records that were documented for other purposes. The study duration may vary according to the commencement of data recording. Completion of the study is limited to the analysis of the data [ 18 , 22 , 24 ]. In 2016, Setia reported that, in some instances, cohort design could not be well-defined as prospective or retrospective; this happened when retrospective and prospective data were collected from the same participants (Table (Table6) 6 ) [ 24 ].
Cohort Study Design | |
Strengths [ , , ] | Limitations [ , , ] |
The temporality between exposure and outcome is well-defined. | Inability to control all the confounding variables. |
Study multiple outcomes in the same exposure. | A prospective cohort design is time-consuming and costly. |
Efficient in rare outcomes if the rare outcome is common in some exposures. | Variables in the retrospective cohort study may not be very accurate since the collected data was not intended for research purposes. |
Accurate measure of variables in prospective cohort design. | May not be very useful in case of rare outcomes. |
The retrospective cohort is relatively fast in conduction and inexpensive. | In the prospective cohort design, the loss of follow-up is a critical problem. |
Lack of bias in the retrospective cohort because the collected data was not initially for research. | Retrospective cohorts may be affected by recall bias. |
It can measure potential causes and relative risk. | Ethical problems. |
The selection of the study design is the most critical step in research methodology [ 4 , 26 ]. An appropriate study design guarantees the achievement of the research objectives. The crucial factors that should be considered in the selection of the study design are the formulated research question, as well as the method of sampling [ 4 , 27 ]. The study design determines the way of sampling and data analysis [ 4 ]. The selection of a research study design depends on many factors. Two crucial points that should be noted during the process selection include different study designs that may be applicable for the same research question(s) and researches may have grey areas in which they have different views about the type of study design [ 4 ].
Conclusions
The selection of appropriate study designs for research is critical. Many research designs can apply to the same research. Appropriate selection guarantees that the author will achieve the research objectives and address the research questions.
Acknowledgments
The author would like to acknowledge Dr. M. Abass, Dr. I. Eljack, Dr. K. Salih, Dr. I. Jack, and my colleagues. Special thanks and appreciation to the college dean and administration of the College of Medicine, University of Bisha (Bisha, Saudi Arabia) for help and allowing the use of facilities.
The content published in Cureus is the result of clinical experience and/or research by independent individuals or organizations. Cureus is not responsible for the scientific accuracy or reliability of data or conclusions published herein. All content published within Cureus is intended only for educational, research and reference purposes. Additionally, articles published within Cureus should not be deemed a suitable substitute for the advice of a qualified health care professional. Do not disregard or avoid professional medical advice due to content published within Cureus.
The authors have declared that no competing interests exist.
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2.2 Research Designs in Psychology
Learning objectives.
- Differentiate the goals of descriptive, correlational, and experimental research designs, and explain the advantages and disadvantages of each.
Psychologists agree that if their ideas and theories about human behaviour are to be taken seriously, they must be backed up by data. Researchers have a variety of research designs available to them in testing their predictions. A research design is the specific method a researcher uses to collect, analyze, and interpret data. Psychologists use three major types of research designs in their research, and each provides an essential avenue for scientific investigation. Descriptive research is designed to provide a snapshot of the current state of affairs. Correlational research is designed to discover relationships among variables. Experimental research is designed to assess cause and effect. Each of the three research designs has specific strengths and limitations, and it is important to understand how each differs. See the table below for a summary.
Research Design | Goal | Advantages | Disadvantages |
---|---|---|---|
Descriptive | To create a snapshot of the current state of affairs. | Provides a relatively complete picture of what is occurring at a given time. Allows the development of questions for further study. | Does not assess relationships among variables. Cannot be used to draw inferences about cause and effect. |
Correlational | To assess the relationships between and among two or more variables. | Allows testing of expected relationships between and among variables and the making of predictions. Can assess these relationships in everyday life events. | Cannot be used to draw inferences about cause and effect. |
Experimental | To assess the causal impact of one or more experimental manipulations on a dependent variable. | Allows conclusions to be drawn about the causal relationships among variables. | Cannot experimentally manipulate many important variables. May be expensive and time-consuming. |
Data source: Stangor, 2011. |
Descriptive research: Assessing the current state of affairs
Descriptive research is designed to create a snapshot of the current thoughts, feelings, or behaviour of individuals. This section reviews four types of descriptive research: case studies, surveys and tests, naturalistic observation, and laboratory observation.
Sometimes the data in a descriptive research project are collected from only a small set of individuals, often only one person or a single small group. These research designs are known as case studies , which are descriptive records of one or more individual’s experiences and behaviour. Sometimes case studies involve ordinary individuals, as when developmental psychologist Jean Piaget used his observation of his own children to develop his stage theory of cognitive development. More frequently, case studies are conducted on individuals who have unusual or abnormal experiences or characteristics, this may include those who find themselves in particularly difficult or stressful situations. The assumption is that carefully studying individuals can give us results that tell us something about human nature. Of course, one individual cannot necessarily represent a larger group of people who were in the same circumstances.
Sigmund Freud was a master of using the psychological difficulties of individuals to draw conclusions about basic psychological processes. Freud wrote case studies of some of his most interesting patients and used these careful examinations to develop his important theories of personality. One classic example is Freud’s description of “Little Hans,” a child whose fear of horses was interpreted in terms of repressed sexual impulses and the Oedipus complex (Freud, 1909/1964).
Another well-known case study is of Phineas Gage, a man whose thoughts and emotions were extensively studied by cognitive psychologists after a railroad spike was blasted through his skull in an accident. Although there are questions about the interpretation of this case study (Kotowicz, 2007), it did provide early evidence that the brain’s frontal lobe is involved in emotion and morality (Damasio et al., 2005). An interesting example of a case study in clinical psychology is described by Milton Rokeach (1964), who investigated in detail the beliefs of and interactions among three patients with schizophrenia, all of whom were convinced they were Jesus Christ.
Research using case studies has some unique challenges when it comes to interpreting the data. By definition, case studies are based on one or a very small number of individuals. While their situations may be unique, we cannot know how well they represent what would be found in other cases. Furthermore, the information obtained in a case study may be inaccurate or incomplete. While researchers do their best to objectively understand one case, making any generalizations to other people is problematic. Researchers can usually only speculate about cause and effect, and even then, they must do so with great caution. Case studies are particularly useful when researchers are starting out to study something about which there is not much research or as a source for generating hypotheses that can be tested using other research designs.
In other cases, the data from descriptive research projects come in the form of a survey , which is a measure administered through either an interview or a written questionnaire to get a picture of the beliefs or behaviours of a sample of people of interest. The people chosen to participate in the research, known as the sample , are selected to be representative of all the people that the researcher wishes to know about, known as the population . The representativeness of samples is enormously important. For example, a representative sample of Canadians must reflect Canada’s demographic make-up in terms of age, sex, gender orientation, socioeconomic status, ethnicity, and so on. Research based on unrepresentative samples is limited in generalizability , meaning it will not apply well to anyone who was not represented in the sample. Psychologists use surveys to measure a wide variety of behaviours, attitudes, opinions, and facts. Surveys could be used to measure the amount of exercise people get every week, eating or drinking habits, attitudes towards climate change, and so on. These days, many surveys are available online, and they tend to be aimed at a wide audience. Statistics Canada is a rich source of surveys of Canadians on a diverse array of topics. Their databases are searchable and downloadable, and many deal with topics of interest to psychologists, such as mental health, wellness, and so on. Their raw data may be used by psychologists who are able to take advantage of the fact that the data have already been collected. This is called archival research .
Related to surveys are psychological tests . These are measures developed by psychologists to assess one’s score on a psychological construct, such as extroversion, self-esteem, or aptitude for a particular career. The difference between surveys and tests is really down to what is being measured, with surveys more likely to be fact-gathering and tests more likely to provide a score on a psychological construct.
As you might imagine, respondents to surveys and psychological tests are not always accurate or truthful in their replies. Respondents may also skew their answers in the direction they think is more socially desirable or in line with what the researcher expects. Sometimes people do not have good insight into their own behaviour and are not accurate in judging themselves. Sometimes tests have built-in social desirability or lie scales that attempt to help researchers understand when someone’s scores might need to be discarded from the research because they are not accurate.
Tests and surveys are only useful if they are valid and reliable . Validity exists when an instrument actually measures what you think it measures (e.g., a test of intelligence that actually measures how many years of education you have lacks validity). Demonstrating the validity of a test or survey is the responsibility of any researcher who uses the instrument. Reliability is a related but different construct; it exists when a test or survey gives the same responses from time to time or in different situations. For example, if you took an intelligence test three times and every time it gave you a different score, that would not be a reliable test. Demonstrating the reliability of tests and surveys is another responsibility of researchers. There are different types of validity and reliability, and there is a branch of psychology devoted to understanding not only how to demonstrate that tests and surveys are valid and reliable, but also how to improve them.
An important criticism of psychological research is its reliance on so-called WEIRD samples (Henrich, Heine, & Norenzayan, 2010). WEIRD stands for Western, educated, industrialized, rich, and democratic. People fitting the WEIRD description have been over-represented in psychological research, while people from poorer, less-educated backgrounds, for example, have participated far less often. This criticism is important because in psychology we may be trying to understand something about people in general. For example, if we want to understand whether early enrichment programs can boost IQ scores later, we need to conduct this research using people from a variety of backgrounds and situations. Most of the world’s population is not WEIRD, so psychologists trying to conduct research that has broad generalizability need to expand their participant pool to include a more representative sample.
Another type of descriptive research is naturalistic observation , which refers to research based on the observation of everyday events. For instance, a developmental psychologist who watches children on a playground and describes what they say to each other while they play is conducting naturalistic observation, as is a biopsychologist who observes animals in their natural habitats. Naturalistic observation is challenging because, in order for it to be accurate, the observer must be effectively invisible. Imagine walking onto a playground, armed with a clipboard and pencil to watch children a few feet away. The presence of an adult may change the way the children behave; if the children know they are being watched, they may not behave in the same ways as they would when no adult is present. Researchers conducting naturalistic observation studies have to find ways to recede into the background so that their presence does not cause the behaviour they are watching to change. They also must find ways to record their observations systematically and completely — not an easy task if you are watching children, for example. As such, it is common to have multiple observers working independently; their combined observations can provide a more accurate record of what occurred.
Sometimes, researchers conducting observational research move out of the natural world and into a laboratory. Laboratory observation allows much more control over the situation and setting in which the participants will be observed. The downside to moving into a laboratory is the potential artificiality of the setting; the participants may not behave the same way in the lab as they would in the natural world, so the behaviour that is observed may not be completely authentic. Consider the researcher who is interested in aggression in children. They might go to a school playground and record what occurs; however, this could be quite time-consuming if the frequency is low or if the children are playing some distance away and their behaviour is difficult to interpret. Instead, the researcher could construct a play setting in a laboratory and attempt to observe aggressive behaviours in this smaller and more controlled context; for instance, they could only provide one highly desirable toy instead of one for each child. What they gain in control, they lose in artificiality. In this example, the possibility for children to act differently in the lab than they would in the real world would create a challenge in interpreting results.
Correlational research: Seeking relationships among variables
In contrast to descriptive research — which is designed primarily to provide a snapshot of behaviour, attitudes, and so on — correlational research involves measuring the relationship between two variables. Variables can be behaviours, attitudes, and so on. Anything that can be measured is a potential variable. The key aspect of correlational research is that the researchers are not asking some of their participants to do one thing and others to do something else; all of the participants are providing scores on the same two variables. Correlational research is not about how an individual scores; rather, it seeks to understand the association between two things in a larger sample of people. The previous comments about the representativeness of the sample all apply in correlational research. Researchers try to find a sample that represents the population of interest.
An example of correlation research would be to measure the association between height and weight. We should expect that there is a relationship because taller people have more mass and therefore should weigh more than short people. We know from observation, however, that there are many tall, thin people just as there are many short, overweight people. In other words, we would expect that in a group of people, height and weight should be systematically related (i.e., correlated), but the degree of relatedness is not expected to be perfect. Imagine we repeated this study with samples representing different populations: elite athletes, women over 50, children under 5, and so on. We might make different predictions about the relationship between height and weight based on the characteristics of the sample. This highlights the importance of obtaining a representative sample.
Psychologists make frequent use of correlational research designs. Examples might be the association between shyness and number of Facebook friends, between age and conservatism, between time spent on social media and grades in school, and so on. Correlational research designs tend to be relatively less expensive because they are time-limited and can often be conducted without much equipment. Online survey platforms have made data collection easier than ever. Some correlational research does not even necessitate collecting data; researchers using archival data sets as described above simply download the raw data from another source. For example, suppose you were interested in whether or not height is related to the number of points scored in hockey players. You could extract data for both variables from nhl.com , the official National Hockey League website, and conduct archival research using the data that have already been collected.
Correlational research designs look for associations between variables. A statistic that measures that association is the correlation coefficient. Correlation coefficients can be either positive or negative, and they range in value from -1.0 through 0 to 1.0. The most common statistical measure is the Pearson correlation coefficient , which is symbolized by the letter r . Positive values of r (e.g., r = .54 or r = .67) indicate that the relationship is positive, whereas negative values of r (e.g., r = –.30 or r = –.72) indicate negative relationships. The closer the coefficient is to -1 or +1, and the further away from zero, the greater the size of the association between the two variables. For instance, r = –.54 is a stronger relationship than r = .30, and r = .72 is a stronger relationship than r = –.57. Correlations of 0 indicate no relationship between the two variables.
Examples of positive correlation coefficients would include those between height and weight, between education and income, and between age and mathematical abilities in children. In each case, people who score higher, or lower, on one of the variables also tend to score higher, or lower, on the other variable. Negative correlations occur when people score high on one variable and low on the other. Examples of negative linear relationships include those between the age of a child and the number of diapers the child uses and between time practising and errors made on a learning task. In these cases, people who score higher on one of the variables tend to score lower on the other variable. Note that the correlation coefficient does not tell you anything about one specific person’s score.
One way of organizing the data from a correlational study with two variables is to graph the values of each of the measured variables using a scatterplot. A scatterplot is a visual image of the relationship between two variables (see Figure 2.3 ). A point is plotted for each individual at the intersection of his or her scores for the two variables. In this example, data extracted from the official National Hockey League (NHL) website of 30 randomly picked hockey players for the 2017/18 season. For each of these players, there is a dot representing player height and number of points (i.e., goals plus assists). The slope or angle of the dotted line through the middle of the scatter tells us something about the strength and direction of the correlation. In this case, the line slopes up slightly to the right, indicating a positive but small correlation. In these NHL players, there is not much of relationship between height and points. The Pearson correlation calculated for this sample is r = 0.14. It is possible that the correlation would be totally different in a different sample of players, such as a greater number, only those who played a full season, only rookies, only forwards, and so on.
For practise constructing and interpreting scatterplots, see the following:
- Interactive Quiz: Positive and Negative Associations in Scatterplots (Khan Academy, 2018)
When the association between the variables on the scatterplot can be easily approximated with a straight line, the variables are said to have a linear relationship . We are only going to consider linear relationships here. Just be aware that some pairs of variables have non-linear relationships, such as the relationship between physiological arousal and performance. Both high and low arousal are associated with sub-optimal performance, shown by a U-shaped scatterplot curve.
The most important limitation of correlational research designs is that they cannot be used to draw conclusions about the causal relationships among the measured variables; in other words, we cannot know what causes what in correlational research. Consider, for instance, a researcher who has hypothesized that viewing violent behaviour will cause increased aggressive play in children. The researcher has collected, from a sample of Grade 4 children, a measure of how many violent television shows each child views during the week as well as a measure of how aggressively each child plays on the school playground. From the data collected, the researcher discovers a positive correlation between the two measured variables.
Although this positive correlation appears to support the researcher’s hypothesis, it cannot be taken to indicate that viewing violent television causes aggressive behaviour. Although the researcher is tempted to assume that viewing violent television causes aggressive play, there are other possibilities. One alternative possibility is that the causal direction is exactly opposite of what has been hypothesized; perhaps children who have behaved aggressively at school are more likely to prefer violent television shows at home.
Still another possible explanation for the observed correlation is that it has been produced by a so-called third variable , one that is not part of the research hypothesis but that causes both of the observed variables and, thus, the correlation between them. In our example, a potential third variable is the discipline style of the children’s parents. Parents who use a harsh and punitive discipline style may allow children to watch violent television and to behave aggressively in comparison to children whose parents use less different types of discipline.
To review, whenever we have a correlation that is not zero, there are three potential pathways of cause and effect that must be acknowledged. The easiest way to practise understanding this challenge is to automatically designate the two variables X and Y. It does not matter which is which. Then, think through any ways in which X might cause Y. Then, flip the direction of cause and effect, and consider how Y might cause X. Finally, and possibly the most challenging, try to think of other variables — let’s call these C — that were not part of the original correlation, which cause both X and Y. Understanding these potential explanations for correlational research is an important aspect of scientific literacy. In the above example, we have shown how X (i.e., viewing violent TV) could cause Y (i.e., aggressive behaviour), how Y could cause X, and how C (i.e., parenting) could cause both X and Y.
Test your understanding with each example below. Find three different interpretations of cause and effect using the procedure outlined above. In each case, identify variables X, Y, and C:
- A positive correlation between dark chocolate consumption and health
- A negative correlation between sleep and smartphone use
- A positive correlation between children’s aggressiveness and time spent playing video games
- A negative association between time spent exercising and consumption of junk food
In sum, correlational research designs have both strengths and limitations. One strength is that they can be used when experimental research is not possible or when fewer resources are available. Correlational designs also have the advantage of allowing the researcher to study behaviour as it occurs in everyday life. We can also use correlational designs to make predictions, such as predicting the success of job trainees based on their test scores during training. They are also excellent sources of suggested avenues for further research, but we cannot use such correlational information to understand cause and effect. For that, researchers rely on experiments.
Experimental research: Understanding the causes of behaviour
The goal of experimental research design is to provide definitive conclusions about the causal relationships among the variables in the research hypothesis. In an experimental research design, there are independent variables and dependent variables. The independent variable is the one manipulated by the researchers so that there is more than one condition. The dependent variable is the outcome or score on the measure of interest that is dependent on the actions of the independent variable. Let’s consider a classic drug study to illustrate the relationship between independent and dependent variables. To begin, a sample of people with a medical condition are randomly assigned to one of two conditions. In one condition, they are given a drug over a period of time. In the other condition, a placebo is given for the same period of time. To be clear, a placebo is a type of medication that looks like the real thing but is actually chemically inert, sometimes referred to as a”sugar pill.” After the testing period, the groups are compared to see if the drug condition shows better improvement in health than the placebo condition.
While the basic design of experiments is quite simple, the success of experimental research rests on meeting a number of criteria. Some important criteria are:
- Participants must be randomly assigned to the conditions so that there are no differences between the groups. In the drug study example, you could not assign the males to the drug condition and the females to the placebo condition. The groups must be demographically equivalent.
- There must be a control condition. Having a condition that does not receive treatment allows experimenters to compare the results of the drug to the results of placebo.
- The only thing that can change between the conditions is the independent variable. For example, the participants in the drug study should receive the medication at the same place, from the same person, at the same time, and so on, for both conditions. Experiments often employ double-blind procedures in which neither the experimenter nor the participants know which condition any participant is in during the experiment. In a single-blind procedure, the participants do not know which condition they are in.
- The sample size has to be large and diverse enough to represent the population of interest. For example, a pharmaceutical company should not use only men in their drug study if the drug will eventually be prescribed to women as well.
- Experimenter effects should be minimized. This means that if there is a difference in scores on the dependent variable, they should not be attributable to something the experimenter did or did not do. For example, if an experiment involved comparing a yoga condition with an exercise condition, experimenters would need to make sure that they treated the participants exactly the same in each condition. They would need to control the amount of time they spent with the participants, how much they interacted verbally, smiled at the participants, and so on. Experimenters often employ research assistants who are blind to the participants’ condition to interact with the participants.
As you can probably see, much of experimental design is about control. The experimenters have a high degree of control over who does what. All of this tight control is to try to ensure that if there is a difference between the different levels of the independent variable, it is detectable. In other words, if there is even a small difference between a drug and placebo, it is detected. Furthermore, this level of control is aimed at ensuring that the only difference between conditions is the one the experimenters are testing while making correct and accurate determinations about cause and effect.
Research Focus
Video games and aggression
Consider an experiment conducted by Craig Anderson and Karen Dill (2000). The study was designed to test the hypothesis that viewing violent video games would increase aggressive behaviour. In this research, male and female undergraduates from Iowa State University were given a chance to play with either a violent video game (e.g., Wolfenstein 3D) or a nonviolent video game (e.g., Myst). During the experimental session, the participants played their assigned video games for 15 minutes. Then, after the play, each participant played a competitive game with an opponent in which the participant could deliver blasts of white noise through the earphones of the opponent. The operational definition of the dependent variable (i.e., aggressive behaviour) was the level and duration of noise delivered to the opponent. The design of the experiment is shown below (see Figure 2.4 ).
There are two strong advantages of the experimental research design. First, there is assurance that the independent variable, also known as the experimental manipulation , occurs prior to the measured dependent variable; second, there is creation of initial equivalence between the conditions of the experiment, which is made possible by using random assignment to conditions.
Experimental designs have two very nice features. For one, they guarantee that the independent variable occurs prior to the measurement of the dependent variable. This eliminates the possibility of reverse causation. Second, the influence of common-causal variables is controlled, and thus eliminated, by creating initial equivalence among the participants in each of the experimental conditions before the manipulation occurs.
The most common method of creating equivalence among the experimental conditions is through random assignment to conditions, a procedure in which the condition that each participant is assigned to is determined through a random process, such as drawing numbers out of an envelope or using a random number table. Anderson and Dill first randomly assigned about 100 participants to each of their two groups: Group A and Group B. Since they used random assignment to conditions, they could be confident that, before the experimental manipulation occurred, the students in Group A were, on average, equivalent to the students in Group B on every possible variable, including variables that are likely to be related to aggression, such as parental discipline style, peer relationships, hormone levels, diet — and in fact everything else.
Then, after they had created initial equivalence, Anderson and Dill created the experimental manipulation; they had the participants in Group A play the violent game and the participants in Group B play the nonviolent game. Then, they compared the dependent variable (i.e., the white noise blasts) between the two groups, finding that the students who had viewed the violent video game gave significantly longer noise blasts than did the students who had played the nonviolent game.
Anderson and Dill had from the outset created initial equivalence between the groups. This initial equivalence allowed them to observe differences in the white noise levels between the two groups after the experimental manipulation, leading to the conclusion that it was the independent variable, and not some other variable, that caused these differences. The idea is that the only thing that was different between the students in the two groups was the video game they had played.
Sometimes, experimental research has a confound. A confound is a variable that has slipped unwanted into the research and potentially caused the results because it has created a systematic difference between the levels of the independent variable. In other words, the confound caused the results, not the independent variable. For example, suppose you were a researcher who wanted to know if eating sugar just before an exam was beneficial. You obtain a large sample of students, divide them randomly into two groups, give everyone the same material to study, and then give half of the sample a chocolate bar containing high levels of sugar and the other half a glass of water before they write their test. Lo and behold, you find the chocolate bar group does better. However, the chocolate bar also contains caffeine, fat and other ingredients. These other substances besides sugar are potential confounds; for example, perhaps caffeine rather than sugar caused the group to perform better. Confounds introduce a systematic difference between levels of the independent variable such that it is impossible to distinguish between effects due to the independent variable and effects due to the confound.
Despite the advantage of determining causation, experiments do have limitations. One is that they are often conducted in laboratory situations rather than in the everyday lives of people. Therefore, we do not know whether results that we find in a laboratory setting will necessarily hold up in everyday life. Do people act the same in a laboratory as they do in real life? Often researchers are forced to balance the need for experimental control with the use of laboratory conditions that can only approximate real life.
Additionally, it is very important to understand that many of the variables that psychologists are interested in are not things that can be manipulated experimentally. For example, psychologists interested in sex differences cannot randomly assign participants to be men or women. If a researcher wants to know if early attachments to parents are important for the development of empathy, or in the formation of adult romantic relationships, the participants cannot be randomly assigned to childhood attachments. Thus, a large number of human characteristics cannot be manipulated or assigned. This means that research may look experimental because it has different conditions (e.g., men or women, rich or poor, highly intelligent or not so intelligent, etc.); however, it is quasi-experimental . The challenge in interpreting quasi-experimental research is that the inability to randomly assign the participants to condition results in uncertainty about cause and effect. For example, if you find that men and women differ in some ability, it could be biology that is the cause, but it is equally likely it could be the societal experience of being male or female that is responsible.
Of particular note, while experiments are the gold standard for understanding cause and effect, a large proportion of psychology research is not experimental for a variety of practical and ethical reasons.
Key Takeaways
- Descriptive, correlational, and experimental research designs are used to collect and analyze data.
- Descriptive designs include case studies, surveys, psychological tests, naturalistic observation, and laboratory observation. The goal of these designs is to get a picture of the participants’ current thoughts, feelings, or behaviours.
- Correlational research designs measure the relationship between two or more variables. The variables may be presented on a scatterplot to visually show the relationships. The Pearson correlation coefficient is a measure of the strength of linear relationship between two variables. Correlations have three potential pathways for interpreting cause and effect.
- Experimental research involves the manipulation of an independent variable and the measurement of a dependent variable. Done correctly, experiments allow researchers to make conclusions about cause and effect. There are a number of criteria that must be met in experimental design. Not everything can be studied experimentally, and laboratory experiments may not replicate real-life conditions well.
Exercises and Critical Thinking
- There is a negative correlation between how close students sit to the front of the classroom and their final grade in the class. Explain some possible reasons for this.
- Imagine you are tasked with creating a survey of online habits of Canadian teenagers. What questions would you ask and why? How valid and reliable would your test be?
- Imagine a researcher wants to test the hypothesis that participating in psychotherapy will cause a decrease in reported anxiety. Describe the type of research design the investigator might use to draw this conclusion. What would be the independent and dependent variables in the research?
Image Attributions
Figure 2.2. This Might Be Me in a Few Years by Frank Kovalchek is used under a CC BY 2.0 license.
Figure 2.3. Used under a CC BY-NC-SA 4.0 license.
Figure 2.4. Used under a CC BY-NC-SA 4.0 license.
Anderson, C. A., & Dill, K. E. (2000). Video games and aggressive thoughts, feelings, and behavior in the laboratory and in life. Journal of Personality and Social Psychology, 78 (4), 772–790.
Damasio, H., Grabowski, T., Frank, R., Galaburda, A. M., Damasio, A. R., Cacioppo, J. T., & Berntson, G. G. (2005). The return of Phineas Gage: Clues about the brain from the skull of a famous patient. In Social neuroscience: Key readings (pp. 21–28). New York, NY: Psychology Press.
Freud, S. (1909/1964). Analysis of phobia in a five-year-old boy. In E. A. Southwell & M. Merbaum (Eds.), Personality: Readings in theory and research (pp. 3–32). Belmont, CA: Wadsworth. (Original work published 1909)
Henrich, J., Heine, S. J., & Norenzaya, A. (2010). The weirdest people in the world? Behavioral and Brain Sciences, 33 , 61–83.
Kotowicz, Z. (2007). The strange case of Phineas Gage. History of the Human Sciences, 20 (1), 115–131.
Rokeach, M. (1964). The three Christs of Ypsilanti: A psychological study . New York, NY: Knopf.
Stangor, C. (2011). Research methods for the behavioral sciences (4th ed.) . Mountain View, CA: Cengage.
Psychology - 1st Canadian Edition Copyright © 2020 by Sally Walters is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.
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Psychologists Use Descriptive, Correlational, and Experimental Research Designs to Understand Behavior
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Learning Objectives
- Differentiate the goals of descriptive, correlational, and experimental research designs and explain the advantages and disadvantages of each.
- Explain the goals of descriptive research and the statistical techniques used to interpret it.
- Summarize the uses of correlational research and describe why correlational research cannot be used to infer causality.
- Review the procedures of experimental research and explain how it can be used to draw causal inferences.
Psychologists agree that if their ideas and theories about human behavior are to be taken seriously, they must be backed up by data. However, the research of different psychologists is designed with different goals in mind, and the different goals require different approaches. These varying approaches, summarized in Table 2.2 , are known as research designs. A research design is the specific method a researcher uses to collect, analyze, and interpret data. Psychologists use three major types of research designs in their research, and each provides an essential avenue for scientific investigation. Descriptive research is research designed to provide a snapshot of the current state of affairs. Correlational research is research designed to discover relationships among variables and to allow the prediction of future events from present knowledge. Experimental research is research in which initial equivalence among research participants in more than one group is created, followed by a manipulation of a given experience for these groups and a measurement of the influence of the manipulation. Each of the three research designs varies according to its strengths and limitations, and it is important to understand how each differs.
Research design | Goal | Advantages | Disadvantages |
Descriptive | To create a snapshot of the current state of affairs | Provides a relatively complete picture of what is occurring at a given time. Allows the development of questions for further study. | Does not assess relationships among variables. May be unethical if participants do not know they are being observed. |
Correlational | To assess the relationships between and among two or more variables | Allows testing of expected relationships between and among variables and the making of predictions. Can assess these relationships in everyday life events. | Cannot be used to draw inferences about the causal relationships between and among the variables. |
Experimental | To assess the causal impact of one or more experimental manipulations on a dependent variable | Allows drawing of conclusions about the causal relationships among variables. | Cannot experimentally manipulate many important variables. May be expensive and time consuming. |
There are three major research designs used by psychologists, and each has its own advantages and disadvantages. |
- Descriptive Research: Assessing the Current State of Affairs
- Correlational Research: Seeking Relationships Among Variables
- Experimental Research: Understanding the Causes of Behavior
- 13626 reads
- Approach and Pedagogy
- The Problem of Intuition Research Focus: Unconscious Preferences for the Letters of Our Own Name
- Why Psychologists Rely on Empirical Methods
- Levels of Explanation in Psychology
- The Challenges of Studying Psychology KET TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Early Psychologists
- Structuralism: Introspection and the Awareness of Subjective Experience
- Functionalism and Evolutionary Psychology
- Psychodynamic Psychology
- Behaviorism and the Question of Free Will Research Focus: Do We Have Free Will?
- The Cognitive Approach and Cognitive Neuroscience The War of the Ghosts
- Social-Cultural Psychology
- The Many Disciplines of Psychology Psychology in Everyday Life: How to Effectively Learn and Remember KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Chapter Summary
- The Scientific Method
- Laws and Theories as Organizing Principles
- The Research Hypothesis
- Conducting Ethical Research Characteristics of an Ethical Research Project Using Human Participants
- Ensuring That Research Is Ethical
- Research With Animals APA Guidelines on Humane Care and Use of Animals in Research KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Experimental Research: Understanding the Causes of Behavior Research Focus: Video Games and Aggression KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- You Can Be an Informed Consumer of Psychological Research Learning Objectives Threats to the Validity of Research Psychology in Everyday Life: Critically Evaluating the Validity of Websites KEY TAKEAWAYS EXERCISISES AND CRITICAL THINKING
- Neurons Communicate Using Electricity and Chemicals Video Clip: The Electrochemical Action of the Neuron
- Neurotransmitters: The Body’s Chemical Messengers KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- The Old Brain: Wired for Survival
- The Cerebral Cortex Creates Consciousness and Thinking
- Functions of the Cortex
- The Brain Is Flexible: Neuroplasticity Research Focus: Identifying the Unique Functions of the Left and Right Hemispheres Using Split-Brain Patients Psychology in Everyday Life: Why Are Some People Left-Handed? KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Lesions Provide a Picture of What Is Missing
- Recording Electrical Activity in the Brain
- Peeking Inside the Brain: Neuroimaging Research Focus: Cyberostracism KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Electrical Control of Behavior: The Nervous System
- The Body’s Chemicals Help Control Behavior: The Endocrine System KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Sensory Thresholds: What Can We Experience? Link
- Measuring Sensation Research Focus: Influence without Awareness KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- The Sensing Eye and the Perceiving Visual Cortex
- Perceiving Color
- Perceiving Form
- Perceiving Depth
- Perceiving Motion Beta Effect and Phi Phenomenon KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Hearing Loss KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Experiencing Pain KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- How the Perceptual System Interprets the Environment Video Clip: The McGurk Effect Video Clip: Selective Attention
- The Important Role of Expectations in Perception Psychology in Everyday Life: How Understanding Sensation and Perception Can Save Lives KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Sleep Stages: Moving Through the Night
- Sleep Disorders: Problems in Sleeping
- The Heavy Costs of Not Sleeping
- Dreams and Dreaming KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Speeding Up the Brain With Stimulants: Caffeine, Nicotine, Cocaine, and Amphetamines
- Slowing Down the Brain With Depressants: Alcohol, Barbiturates and Benzodiazepines, and Toxic Inhalants
- Opioids: Opium, Morphine, Heroin, and Codeine
- Hallucinogens: Cannabis, Mescaline, and LSD
- Why We Use Psychoactive Drugs Research Focus: Risk Tolerance Predicts Cigarette Use KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Changing Behavior Through Suggestion: The Power of Hypnosis
- Reducing Sensation to Alter Consciousness: Sensory Deprivation
- Meditation Video Clip: Try Meditation Psychology in Everyday Life: The Need to Escape Everyday Consciousness KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- How the Environment Can Affect the Vulnerable Fetus KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- The Newborn Arrives With Many Behaviors Intact Research Focus: Using the Habituation Technique to Study What Infants Know
- Cognitive Development During Childhood
- Video Clip: Object Permanence
- Social Development During Childhood
- Knowing the Self: The Development of the Self-Concept
- Video Clip: The Harlows’ Monkeys
- Video Clip: The Strange Situation Research Focus: Using a Longitudinal Research Design to Assess the Stability of Attachment KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Physical Changes in Adolescence
- Cognitive Development in Adolescence
- Social Development in Adolescence
- Developing Moral Reasoning: Kohlberg’s Theory
- Video Clip: People Being Interviewed About Kohlberg’s Stages KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Physical and Cognitive Changes in Early and Middle Adulthood
- Social Changes in Early and Middle Adulthood KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Cognitive Changes During Aging
- Dementia and Alzheimer’s Disease
- Social Changes During Aging: Retiring Effectively
- Death, Dying, and Bereavement KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Pavlov Demonstrates Conditioning in Dogs
- The Persistence and Extinction of Conditioning
- The Role of Nature in Classical Conditioning KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- How Reinforcement and Punishment Influence Behavior: The Research of Thorndike and Skinner
- Video Clip: Thorndike’s Puzzle Box
- Creating Complex Behaviors Through Operant Conditioning KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Observational Learning: Learning by Watching
- Video Clip: Bandura Discussing Clips From His Modeling Studies Research Focus: The Effects of Violent Video Games on Aggression KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Using Classical Conditioning in Advertising
- Video Clip: Television Ads Psychology in Everyday Life: Operant Conditioning in the Classroom
- Reinforcement in Social Dilemmas KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Video Clip: Kim Peek
- Explicit Memory
- Implicit Memory Research Focus: Priming Outside Awareness Influences Behavior
- Stages of Memory: Sensory, Short-Term, and Long-Term Memory
- Sensory Memory
- Short-Term Memory KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Encoding and Storage: How Our Perceptions Become Memories Research Focus: Elaboration and Memory
- Using the Contributions of Hermann Ebbinghaus to Improve Your Memory
- The Structure of LTM: Categories, Prototypes, and Schemas
- The Biology of Memory KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Source Monitoring: Did It Really Happen?
- Schematic Processing: Distortions Based on Expectations
- Misinformation Effects: How Information That Comes Later Can Distort Memory
- Overconfidence
- Heuristic Processing: Availability and Representativeness
- Salience and Cognitive Accessibility
- Counterfactual Thinking Psychology in Everyday Life: Cognitive Biases in the Real World KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- How We Talk (or Do Not Talk) about Intelligence How We Talk (or Do Not Talk) about Intelligence
- General (g) Versus Specific (s) Intelligences
- Measuring Intelligence: Standardization and the Intelligence Quotient
- The Biology of Intelligence
- Is Intelligence Nature or Nurture? Psychology in Everyday Life: Emotional Intelligence KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Extremes of Intelligence: Retardation and Giftedness
- Extremely Low Intelligence
- Extremely High Intelligence
- Sex Differences in Intelligence
- Racial Differences in Intelligence Research Focus: Stereotype Threat KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- The Components of Language Examples in Which Syntax Is Correct but the Interpretation Can Be Ambiguous
- The Biology and Development of Language Research Focus: When Can We Best Learn Language? Testing the Critical Period Hypothesis
- Learning Language
- How Children Learn Language: Theories of Language Acquisition
- Bilingualism and Cognitive Development
- Can Animals Learn Language?
- Video Clip: Language Recognition in Bonobos
- Languageand Perception KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Captain Sullenberger Conquers His Emotions Captain Sullenberger Conquers His Emotions
- Video Clip: The Basic Emotions
- The Cannon-Bard and James-Lange Theories of Emotion Research Focus: Misattributing Arousal
- Communicating Emotion KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- The Negative Effects of Stress
- Stressors in Our Everyday Lives
- Responses to Stress
- Managing Stress
- Emotion Regulation Research Focus: Emotion Regulation Takes Effort KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Finding Happiness Through Our Connections With Others
- What Makes Us Happy? KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Eating: Healthy Choices Make Healthy Lives
- Sex: The Most Important Human Behavior
- The Experience of Sex
- The Many Varieties of Sexual Behavior Psychology in Everyday Life: Regulating Emotions to Improve Our Health KEY TAKEAWAYS EXERCISE AND CRITICAL THINKING
- Identical Twins Reunited after 35 Years Identical Twins Reunited after 35 Years
- Personality as Traits Example of a Trait Measure
- Situational Influences on Personality
- The MMPI and Projective Tests Psychology in Everyday Life: Leaders and Leadership KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Psychodynamic Theories of Personality: The Role of the Unconscious
- Id, Ego, and Superego Research Focus: How the Fear of Death Causes Aggressive Behavior
- Strengths and Limitations of Freudian and Neo-Freudian Approaches
- Focusing on the Self: Humanism and Self-Actualization Research Focus: Self-Discrepancies, Anxiety, and Depression KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Studying Personality Using Behavioral Genetics
- Studying Personality Using Molecular Genetics
- Reviewing the Literature: Is Our Genetics Our Destiny? KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- When Minor Body Imperfections Lead to Suicide When Minor Body Imperfections Lead to Suicide
- Defining Disorder Psychology in Everyday Life: Combating the Stigma of Abnormal Behavior
- Diagnosing Disorder: The DSM
- Diagnosis or Overdiagnosis? ADHD, Autistic Disorder, and Asperger’s Disorder
- Attention-Deficit/Hyperactivity Disorder (ADHD)
- Autistic Disorder and Asperger’s Disorder KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Generalized Anxiety Disorder
- Panic Disorder
- Obsessive-Compulsive Disorders
- Posttraumatic Stress Disorder (PTSD)
- Dissociative Disorders: Losing the Self to Avoid Anxiety
- Dissociative Amnesia and Fugue
- Dissociative Identity Disorder
- Explaining Anxiety and Dissociation Disorders KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Dysthymia and Major Depressive Disorder
- Bipolar Disorder
- Explaining Mood Disorders Research Focus: Using Molecular Genetics to Unravel the Causes of Depression KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Symptoms of Schizophrenia
- Explaining Schizophrenia KEY TAKEAWAYS EXERCISE AND CRITICAL THINKING
- Borderline Personality Disorder Research Focus: Affective and Cognitive Deficits in BPD
- Antisocial Personality Disorder (APD) KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Somatoform and Factitious Disorders
- Sexual Disorders
- Disorders of Sexual Function
- Gender Identity Disorder
- Paraphilias KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Therapy on Four Legs Therapy on Four Legs
- Psychodynamic Therapy Important Characteristics and Experiences in Psychoanalysis
- Humanistic Therapies
- Behavioral Aspects of CBT
- Cognitive Aspects of CBT
- Combination (Eclectic) Approaches to Therapy KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Drug Therapies
- Using Stimulants to Treat ADHD
- Antidepressant Medications
- Antianxiety Medications
- Antipsychotic Medications
- Direct Brain Intervention Therapies KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Group, Couples, and Family Therapy
- Self-Help Groups
- Community Mental Health: Service and Prevention Some Risk Factors for Psychological Disorders Research Focus: The Implicit Association Test as a Behavioral Marker for Suicide KEY TAKEAWAYS EXERCISE AND CRITICAL THINKING
- Effectiveness of Psychological Therapy ResearchFocus:Meta-AnalyzingClinicalOutcomes
- Effectiveness of Biomedical Therapies
- Effectiveness of Social-CommunityApproaches KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Binge Drinking and the Death of a Homecoming Queen Binge Drinking and the Death of a Homecoming Queen
- Perceiving Others
- Forming Judgments on the Basis of Appearance: Stereotyping, Prejudice, and Discrimination Implicit Association Test Research Focus: Forming Judgments of People in Seconds
- Close Relationships
- Causal Attribution: Forming Judgments by Observing Behavior
- Attitudes and Behavior KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Helping Others: Altruism Helps Create Harmonious Relationships
- Why Are We Altruistic?
- How the Presence of Others Can Reduce Helping
- Video Clip: The Case of Kitty Genovese
- Human Aggression: An Adaptive y et Potentially Damaging Behavior
- The Ability to Aggress Is Part of Human Nature
- Negative Experiences Increase Aggression
- Viewing Violent Media Increases Aggression
- Video Clip Research Focus: The Culture of Honor
- Conformity and Obedience: How Social Influence Creates Social Norms
- Do We Always Conform? KEY TAKEAWAYS EXERCISES AND CRITICAL THINKING
- Working in Front of Others: Social Facilitation and Social Inhibition
- Working Together in Groups Psychology in Everyday Life: Do Juries Make Good Decisions?
- Using Groups Effectively KEY TAKEAWAYS EXERCISE AND CRITICAL THINKING
- Back Matter
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Descriptive research is research designed to provide a snapshot of the current state of affairs. Correlational research is research designed to discover relationships among variables and to allow the prediction of future events from present knowledge.
A descriptive research project seeks to comprehend phenomena or groups in depth. Correlational research, on the other hand, is a method that describes and predicts how variables are naturally related in the real world without the researcher attempting to alter them or assign causation between them.
Differentiate the goals of descriptive, correlational, and experimental research designs and explain the advantages and disadvantages of each. Explain the goals of descriptive research and the statistical techniques used to interpret it.
Descriptive research gathers data without controlling any variables, while experimental research manipulates and controls variables to determine cause and effect. Do you want to identify characteristics, patterns and correlations or test causal relationships between variables ?
In an experimental design, you manipulate an independent variable and measure its effect on a dependent variable. Other variables are controlled so they can’t impact the results. In a correlational design, you measure variables without manipulating any of them.
Descriptive research means observing and measuring without manipulating variables. It can identify characteristics, trends and correlations.
The observational design is subdivided into descriptive, including cross-sectional, case report or case series, and correlational, and analytic which includes cross-section, case-control, and cohort studies. Each research design has its uses and points of strength and limitations.
Descriptive, correlational, and experimental research designs are used to collect and analyze data. Descriptive designs include case studies, surveys, psychological tests, naturalistic observation, and laboratory observation.
Correlational research: examines two variables at once, and may be used to identify patterns of relationships. Experimental research: determines cause and effect by exposing one group to a...
Descriptive research is research designed to provide a snapshot of the current state of affairs. Correlational research is research designed to discover relationships among variables and to allow the prediction of future events from present knowledge.