If in a repeated measures design, extremely low scores improve over time (or extremely high scores decrease over time), which threat to internal validity should we be worried about?
A) Instrumentation
B) Diffusion of treatments
C) Statistical regression
D) History

Question

Quizplus · Accepted Answer

Statistical regression is a threat to internal validity that occurs when extreme scores tend to move towards the mean over time, which can be mistaken for a treatment effect.

If in a Repeated Measures Design, Extremely Low Scores Improve