A researcher uses matching to constitute his control group, while performing a study on psychotherapy as an adjunct treatment for substance addiction. What type of validity might be enhanced by matching, in this instance?

Question

a. Construct validity
b. Statistical conclusion validity
c. External validity
d. Internal validity

Answer 1

ANS: D
Matching is used when a subject in the experimental group is randomly selected and then a subject similar in relation to important extraneous variables is randomly selected for the control group. For example, subjects in the experimental and control groups might be matched for age, gender, severity of illness, or number of chronic illnesses. Statistical conclusion validity is concerned with whether the conclusions about relationships or differences drawn from statistical analysis are an accurate reflection of the real world: it is not affected by use of matching. Internal validity is the extent to which the effects detected in the study are a true reflection of reality rather than the result of extraneous variables: matching can increase internal validity if the researcher can correctly identify the principal extraneous variables. Construct validity examines the fit between the conceptual definitions and operational definitions of variables: matching has no effect on this. External validity is concerned with the extent to which study findings can be generalized beyond the sample used in the study; matching does not affect external validity, to any extent.