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Experimental and Correlational Research Methods for AP Psychology (page 2)

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By — McGraw-Hill Professional
Updated on Mar 4, 2011

Correlational Research

Although experiments conducted under carefully controlled conditions help establish cause and effect relationships, the time, expense, and artificiality of the environment limits that type of research. Psychologists more often use descriptive and correlational research methods such as survey methods that involve interviews or questionnaires, tests, and naturalistic observation. Correlational methods look at the relationship between two variables without establishing cause and effect relationships. The goal is to determine to what extent one variable predicts the other. Many factors that seem to be causally related are not. Often it's a third factor that causes the other two.

Naturalistic Observation

Naturalistic observation is carried out in the field where naturally occurring behavior can be observed. Naturalistic observation studies gather descriptive information about typical behavior of people or other animals without manipulating any variables. For example, Jane Goodall's team of scientists has been observing the behavior of chimpanzees in the wild for decades. Such studies have enabled scientists to predict when the chimps will fight each other or when they will mate. Similarly, other scientists have been studying human behavior in the workplace, in schools, in bars, etc. The data can be used for correlational analysis or for generating ideas for other research.

Survey Method

In the survey method, researchers use questionnaires or interviews to ask a large number of people questions about their behaviors, thoughts, and attitudes. In order for the information to be useful, the participants in the study should be representative of a larger population, which can best be achieved by random sampling. Accuracy of data is an issue because people sometimes distort their answers to appear more "politically correct," or they fail to recall information correctly. The data from surveys can be used for correlational analysis or for generating ideas for other research.

Retrospective or ex post facto studies look at an effect and seek the cause. For example, when researchers found an increase in babies being born with deformed limbs, especially in England but also in the United States and other western countries in the early 1970s, they asked the mothers of the babies many questions, then compared the answers of all of the mothers through correlational analysis. They found the strongest relationship between the mother taking the drug thalidomide during the pregnancy and the appearance of the limb deformities in the babies. Controlled experiments with rodents verified that the drug caused abnormal limb development in the babies of the animals.

Test Method

Tests are procedures used to measure attributes of individuals at a particular time and place. Like surveys, tests can be used to gather huge amounts of information relatively quickly and cheaply. Results of tests can be used for correlational analysis or for generating ideas for other research.

For surveys or tests to be accurate measures of behaviors or mental processes, they must be both reliable and valid. Reliability is consistency or repeatability. Subjects should answer questions the same way on two different occasions. A subject should also get the same score on a test on two different occasions. Validity is the extent to which an instrument measures or predicts what it is supposed to. Questions about frequency of showering would not be valid indicators of cooking ability. Algebra questions would not be valid measures of what you learned in this chapter.

Case Study

Another research method, the case study method, is an in-depth examination of a specific group or single person that typically includes interviews, observations, and test scores. The intensive description and analysis of the small group or individual is especially useful for understanding complex or rare phenomena. For example, case studies done on patients with gunshot wounds to the head enabled scientists to better understand how the loss of brain tissue affected specific aspects of behavior. Case studies have enabled us to better understand a wide range of topics, from how the brain processes information to autism. Clinical psychologists frequently do case studies.

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