Of the following, ______ are not considered a source of bias problematic in pretest-posttest designs.
A) history effects
B) testing effects
C) group differences
D) placebo effects

Question

Quizplus · Accepted Answer

Placebo effects are not typically considered a source of bias in pretest-posttest designs, as they would affect both the pretest and posttest equally. History effects refer to outside events that may affect the outcome being measured, testing effects refer to the influence of taking the pretest on the posttest results, and group differences refer to differences between the groups being compared that may affect the outcome.

Of the Following, ______ Are Not Considered a Source of Bias