Which of the following is a threat to internal validity found in within-groups designs but not in independent-groups designs?
A)Selection effects
B)Design confounds
C)Demand characteristics
D)Practice effects

Question

Quizplus · Accepted Answer

Practice effects occur when participants' performance on a measure is influenced by prior exposure to that measure. This is a threat to internal validity in within-groups designs because participants are tested multiple times, whereas in independent-groups designs, each participant is only tested once. Therefore, practice effects are not a threat to internal validity in independent-groups designs. The other options (selection effects, design confounds, and demand characteristics) can be threats to internal validity in both within-groups and independent-groups designs.

Which of the Following Is a Threat to Internal Validity