If subjects participating in a two-group pretest-posttest design research study about bipolar disorder are given a knowledge test about the disorder being studied multiple times, what is the potential disadvantage?
A) The selection bias of only choosing subjects that take the test.
B) There will be an apparent lack of differences between the results
C) A threat to validity and mortality from repeated subject testing.
D) The longer time needed for testing requires a larger sample size.

Question

Quizplus · Accepted Answer

Repeated testing can lead to practice effects, where subjects improve simply because they have taken the test multiple times, threatening the study's validity. Additionally, repeated testing can lead to participant dropout, affecting mortality rates.

If Subjects Participating in a Two-Group Pretest-Posttest Design Research Study