Participants for a treatment group are chosen because they score very low on a pretest measure of performance.When their performance improves on the posttest,the researcher
A) should consider the possibility that statistical regression influenced posttest scores.
B) can rule out testing and instrumentation threats to internal validity.
C) can be confident that the treatment was effective.
D) must conclude that additive effects with selection are responsible for the outcome.

Question

Quizplus · Accepted Answer

Participants who score very low on a pretest measure of performance are likely to show regression to the mean, which could influence posttest scores. Therefore, the possibility of statistical regression should be considered before drawing any conclusions about the effectiveness of the treatment.

Participants for a Treatment Group Are Chosen Because They Score