In order to be a threat to the internal validity of an experimental study, an extraneous variable such as age must:
A) be related to the dependent variable
B) differ among treatment groups
C) both A and B
D) neither A nor B

Question

Quizplus · Accepted Answer

An extraneous variable must be related to the dependent variable and differ among treatment groups to threaten the internal validity of an experimental study, as it could then potentially influence the outcome in a way that confounds the results attributed to the independent variable.

In Order to Be a Threat to the Internal Validity