When a pretest and posttest are used on all subjects in the experimental and control groups
A) the pretest may influence posttest results.
B) the experimenter knows whether it is reasonable to assume that both groups began at a similar point.
C) there may be interaction between pretest and treatment effects.
D) a and b
E) a, b, and c

Question

Quizplus · Accepted Answer

When a pretest and posttest are used on all subjects in both the experimental and control groups, it allows for the assessment of whether the groups started at a similar point (B), but it also introduces the possibility that the pretest itself may influence the outcomes measured in the posttest (A), and there may be interactions between the pretest and the treatment effects (C).

When a Pretest and Posttest Are Used on All Subjects