When it is not possible to make sure that groups in a study have identical characteristics before the administration of an experimental treatment, the researcher should be concerned with
A)testing effects.
B)interaction.
C)selection bias.
D)maturation effects.
E)history effects.

Question

Quizplus · Accepted Answer

When groups are not identical before the administration of an experimental treatment, the researcher should be concerned with selection bias. Selection bias occurs when there are systematic differences between groups that are not accounted for, leading to potentially inaccurate results. The other options listed (testing effects, interaction, maturation effects, and history effects) are all potential threats to internal validity, but are not specifically related to the issue of group characteristics not being identical.

When It Is Not Possible to Make Sure That Groups