Imagine a hypothetical study using a nonequivalent comparison group designed to assess the effectiveness of an anti-drug, "Just Say No," campaign. In this study students at school X receive a semester-long series of "Just Say No" lectures. Students at school Y across town do not receive the intervention. Unfortunately, during the semester a student at school Y died after an accidental drug overdose. This incident may have influenced drug use at school Y but not school X) and consequently make it impossible to interpret our research findings. Which of the following threats to internal validity is present in this study?
A) selection-instrumentation
B) selection-maturation
C) selection-history
D) selection-testing

Question

Quizplus · Accepted Answer

The correct answer is selection-history because the external event (a student's accidental drug overdose at school Y) that occurred during the study could have influenced the outcomes independently of the intervention, making it difficult to attribute any differences in drug use between the schools solely to the "Just Say No" campaign.

Imagine a Hypothetical Study Using a Nonequivalent Comparison Group Designed