The fact that people who choose to, or who are chosen to be, in a program are different from those who are not in a program creates the threat to internal validity called
A) history.
B) regression to the mean.
C) selection.
D) testing.

Question

Quizplus · Accepted Answer

Selection refers to the possibility that differences between groups being compared may be due to the characteristics of the individuals in each group rather than the effects of the intervention or treatment being studied. In this case, the individuals who choose or are selected to participate in a program may differ in important ways from those who do not, and these differences could account for any observed effects of the program. The other options (history, regression to the mean, and testing) are all potential threats to internal validity as well, but they do not specifically relate to differences between groups at the outset of a study.

The Fact That People Who Choose To, or Who Are