One strategy for dealing with preexisting differences between experimental and control groups in the nonequivalent comparison group design is to match the participants.
A) this procedure is as effective as randomly assigning participants from the start
B) this procedure eliminates local history as a confounding factor
C) this procedure, however, may introduce a regression-artifact phenomenon whenextreme scores are frequently needed to match
D) this procedure, however, confounds the research even more than the preexisting differences

Question

Quizplus · Accepted Answer

Matching participants in nonequivalent comparison group designs can introduce a regression artifact, especially when matching is done on extreme scores. This phenomenon occurs because extreme scores tend to regress to the mean upon retesting, which can be mistakenly interpreted as a treatment effect.

One Strategy for Dealing with Preexisting Differences Between Experimental and Control