A researcher wishes to test whether a new treatment is effective for patients with arachnophobia (fear of spiders). The researcher chooses a group of patients who he thinks can handle the treatment and has another group of patients as a control. He reports that, following exposure therapy, those in the experimental group showed less fear of spiders than those in the control group. What is the hidden flaw with this study that limits its claims?

Question

Quizplus · Accepted Answer

Without random assignment, the researcher cannot confidently conclude that any differences between the experimental and control groups are due to the treatment and not other factors, such as pre-existing differences between the groups. Therefore, it is not a true experiment.

A Researcher Wishes to Test Whether a New Treatment Is