Why does an observational study have a greater risk of selection bias than an experimental study?
A) it does not do random sampling in every case
B) posttest measurement is not done by the study
C) There is no random assignment of an independent variable.
D) it may have missing or incomplete data

Question

Quizplus · Accepted Answer

In observational studies, researchers do not randomly assign participants to different groups or conditions, which increases the risk of selection bias as the groups may differ in ways other than the independent variable being studied.

Why Does an Observational Study Have a Greater Risk of Selection