Which of the following is not an advantage of a prospective cohort study?

• A. Precise measurement of exposure is possible
• B. It usually costs less than a case-control study
• C. Incidence rates can be calculated
• D. Recall bias is minimized compared with a case-control study

Answer: (B)

Not an advantage is the notion that it usually costs less than a case-control study. Prospective cohort studies require enrolling a large group and following them over time, collecting exposure data as events occur and monitoring outcomes, often for many years. This ongoing data collection and long follow-up drive higher costs and logistical demands compared with case-control studies, which are typically cheaper because they start with cases and controls and look back at exposures.

In contrast, precise measurement of exposure is attainable because data can be gathered before outcomes happen, not rely on participants’ memory after disease onset. Incidence rates can be calculated directly from the follow-up of the cohort, and recall bias is minimized since exposure information is collected prospectively rather than after disease has occurred.