How does the pretest-posttest control-group design control for the problem of selection?
A) Participants are randomly assigned to groups, so we can assume that the groups are equivalent before the experiment.
B) Participants are randomly selected, so we can assume that the groups are equivalent before the experiment.
C) There is a placebo group, so we can assume that demand characteristics are controlled.
D) There are two more groups in the experiment, so external validity is increased.

Question

Quizplus · Accepted Answer

Random assignment to groups ensures that any differences between groups are due to chance, making them equivalent before the experiment.

How Does the Pretest-Posttest Control-Group Design Control for the Problem