A researcher does a study of a mathematics program in a one-group pretest-posttest design. She gives the group of second graders a multiple-choice pretest. Unknown to her, the children had never taken a multiple-choice test. The children scored higher on the same test given at posttest. She argues that the children improved because of the mathematics program. That the children had never taken a multiple-choice test before and showed improvement at posttest suggests that one possible threat to her conclusion is a:
A) History effect
B) Multiple-treatment interference
C) Testing effect
D) Selection effect

Question

Quizplus · Accepted Answer

The testing effect is a threat to the conclusion because the children's improvement could be due to their increased familiarity with the test format, rather than the mathematics program itself.

A Researcher Does a Study of a Mathematics Program in a One-Group