MCAT · Psychological, Social, and Biological Foundations of Behavior · Research Methods

Research design and statistics

Research design and statistics is part of Research Methods in the MCAT Psychological, Social, and Biological Foundations of Behavior section. The questions below are written in the style of the real test, each with the answer and a worked explanation.

Question types you will see here include confounds and third variables, internal versus external validity, correlation, causation and regression and sampling methods and selection bias.

Common traps: proposing a variable the design already controls; reversing cause and effect; calling a mediating variable a confound.

Sample questions

Question 1
In a study of aggression, researchers define aggression as the number of times a child hits a toy doll during a 10-minute play session. This definition is:
- A.
  a hypothesis
- B.
  a confounding variable in the study
- C.
  an operational definition
- D.
  an independent variable
Answer: C. an operational definition
An operational definition specifies exactly how an abstract concept will be measured or manipulated in a study, such as counting hits on a doll to measure aggression. A hypothesis is a testable prediction about the relationship between variables, not a specification of how one variable is measured.
Question 2
Factory workers become more productive during a study simply because they know researchers are observing them, regardless of which changes are made to their working conditions. This is:
- A.
  the Hawthorne effect
- B.
  the placebo effect
- C.
  regression to the mean
- D.
  selection bias
Answer: A. the Hawthorne effect
The Hawthorne effect is a change in behavior that occurs because participants know they are being observed. The placebo effect is improvement caused by the expectation that a treatment will work, rather than by awareness of being observed.

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