In Katia's remedial mathematics study, she collected pretest data from a group of participants. She divided the participants into three groups. One group received no treatment, one group received instruction by a teacher-delivered intervention, one group received peer tutoring on the same problems. After the intervention she tested their math skills. With which validity threat should Katia be most concerned?
A) Maturation
B) Testing
C) Instrumentation
D) Pretest-treatment interaction

Question

Quizplus · Accepted Answer

The pretest-treatment interaction is the greatest validity threat in this situation because it is possible that the pretest influenced the results differently across the groups. For example, if one group scored much higher on the pretest than the others, their scores after the intervention may be due to regression to the mean rather than the intervention itself. This threat can be minimized by randomizing participants to groups or using a control group with a different pretest.

In Katia's Remedial Mathematics Study, She Collected Pretest Data from a Group