To ensure internal validity of a pretest-posttest design, you must:
A) include a large sample of subjects.
B) include control groups that are not exposed to your treatment.
C) conduct your research in your subjects' natural environment.
D) All of the answers are correct.

Question

Quizplus · Accepted Answer

Including control groups that are not exposed to the treatment helps to ensure that any changes observed in the experimental group can be attributed to the treatment itself, thus maintaining internal validity.

To Ensure Internal Validity of a Pretest-Posttest Design, You Must