Multiple pretest and posttest measures are valuable in before-and-after designs because they decrease the possibility of internal invalidity due to ______.
A) selection
B) external events
C) compensation
D) interaction of testing and treatment

Question

Quizplus · Accepted Answer

Multiple pretest and posttest measures help in identifying and controlling for the effects of external events that might influence the outcome, thereby reducing the risk of attributing changes to the intervention when they might actually be due to other factors.

Multiple Pretest and Posttest Measures Are Valuable in Before-And-After Designs