You conduct a study on a group of individuals to examine the role of exercise in alleviating depression.You assign the first 50 people who are motivated to sign up to the experimental group,and the second group of 50 people,who sign up much later,to the control group.After one month,you find that the people in the experimental group (who exercised three times a week on average)are significantly less depressed than the people in the control group (who exercised once a week on average).Although you may be tempted to conclude that exercise helps stave off depression,you cannot because of the lack of _____ in your study.

Question

Quizplus · Accepted Answer

The lack of random assignment is the issue in this study. Random assignment would ensure that each participant has an equal chance of being placed in either the experimental or control group, which reduces the risk of selection bias. In this study, the first 50 individuals were assigned to the experimental group and the second 50 were assigned to the control group, which could introduce bias into the results. Therefore, without random assignment, it is difficult to conclude that exercise is the only factor responsible for the difference in depression levels between the two groups.

You Conduct a Study on a Group of Individuals to Examine