Which threat to internal validity occurs in any study with nonequivalent groups and prevents researchers from making conclusive claims about causality?
A) Order effects
B) Instrumentation effects
C) Regression toward the mean
D) Individual differences

Question

Quizplus · Accepted Answer

Individual differences threat to internal validity occurs in studies with nonequivalent groups because the groups may differ in many ways other than the independent variable being studied, making it difficult to attribute any differences in outcomes to the independent variable alone.

Which Threat to Internal Validity Occurs in Any Study with Nonequivalent