What is the role of the comparison group in a cohort study?

• A. A Group Not Exposed To The Exposure Of Interest
• B. A Group Exposed To The Exposure Of Interest
• C. A Group That Receives A Different Therapy
• D. A Group Selected Randomly From The Population

Answer: (A)

In a cohort study, you measure how an exposure might influence the development of an outcome by following groups over time and comparing how often the outcome occurs in each group. The comparison group is the group not exposed to the exposure of interest. This unexposed group provides the baseline risk against which the exposed group is measured, allowing calculation of measures like relative risk. Ideally, the two groups are similar in other ways so that differences in outcomes can be attributed to the exposure rather than other factors.

Choosing a group that receives a different therapy would introduce a different exposure and potential confounding, which isn’t the standard role of the comparison group. Simply selecting a group randomly from the population describes sampling, not the specific function of the comparison group in assessing exposure effects.