Social & Preventive Medicine Bias is unlikely to invalidate cohort studies used to assess risk of exposure because – A Data collection is prospective B Large number of subjects is usually included C Exposure is usually determined prior to disease occurrence D Actual relative risk can be determined 💡 Explanation Bias is unlikely to invalidate cohort studies used to assess risk of exposure because - ✓ Correct Answer: C. Exposure is usually determined prior to disease occurrence