Which of the following is a weakness of a posttest-only control group design?

A) Researchers have limited information available about group equivalence prior to treatment.
B) It is expensive to the researcher in terms of time and effort.
C) Confidentiality of the responses is compromised as the participants are unable to respond anonymously.
D) Repeated testing may be occasionally bothersome to some participants.

Posttest-Only Control

A research design in which outcomes are measured only after the experimental intervention, without a pretest, to assess the intervention's effect.

Group Equivalence

A condition in experimental research where the groups being compared are equal or similar in all relevant aspects except for the intervention being tested.

Repeated Testing

The process of conducting the same test multiple times to verify the reliability and consistency of its results.