The main threat to the external validity of the pretest-posttest control-group design is the
A) Hawthorne effect.
B) interaction between history and the experimental treatment.
C) interaction between time of measurement and the experimental treatment.
D) interaction between the pretest and the experimental treatment.

Question

Quizplus · Accepted Answer

The main threat to the external validity of the pretest-posttest control-group design is the interaction between the pretest and the experimental treatment. This occurs when the pretest influences how participants respond to the experimental treatment, potentially limiting the generalizability of the findings to populations or situations where a pretest is not given.

The Main Threat to the External Validity of the Pretest-Posttest