Dr. Prutherow believes that people who are under stress will develop more colds than people who are not under stress. When he randomly selects ten participants and exposes them to high levels of stress, he finds that nine of the participants develop colds. Based on these results, he concludes that stress causes an increase in colds. Dr. Prutherow's reasoning may be flawed because

Question

Quizplus · Accepted Answer

Dr. Prutherow's study lacks a control group, which is essential for comparing the outcomes of those exposed to the variable of interest (stress) with those who are not. This comparison helps establish a causal relationship.

Dr Prutherow Believes That People Who Are Under Stress Will