Sensitivity vs. Specificity: Sensitivity refers to the rate of which measure?

• A. Rate of false positives
• B. Rate of true positives
• C. Rate of true negatives
• D. Rate of false negatives

Answer: (B)

Sensitivity measures the test’s ability to correctly identify people who have the condition. It is the true positive rate—among those who truly have the condition, what fraction test positive. In formula terms, sensitivity = true positives / (true positives + false negatives). A high sensitivity means few false negatives, so the test catches most actual cases. This is different from specificity, which is about correctly ruling out those without the condition (true negatives).