In research studies, mothers are not randomly assigned to use drugs such as cocaine. This methodological problem is called
A) a sampling error.
B) attrition.
C) the placebo effect.
D) a selection factor.

Question

Quizplus · Accepted Answer

This is called a selection factor because the participants in the study (in this case, mothers using drugs such as cocaine) are not randomly assigned, which can lead to differences between groups that are not due to the experimental manipulation.

In Research Studies, Mothers Are Not Randomly Assigned to Use