If there is no way of certifying that groups of test units were equivalent at some prior time, this is said to be evidence of

Question

Quizplus · Accepted Answer

Selection bias occurs when the groups being compared are not equivalent because of the way in which they were selected or assigned, which can lead to inaccurate conclusions if the groups differ in significant ways that affect the outcome of the study.

If There Is No Way of Certifying That Groups of Test