Which metric is defined as TP divided by (TP plus FN)?

• A. Diagnostic Sensitivity
• B. Diagnostic Specificity
• C. Positive Predictive Value
• D. Negative Predictive Value

Answer: (A)

Sensitivity is the test’s ability to correctly identify those who have the disease, defined as TP divided by (TP plus FN). This means it measures the proportion of actual disease cases that the test catches as positive. In other words, it answers: among people who truly have the disease, how many are detected? The formula TP/(TP+FN) directly reflects this, with true positives in the numerator and false negatives in the denominator. The other metrics use different combinations: specificity is TN/(TN+FP), while positive predictive value is TP/(TP+FP) and negative predictive value is TN/(TN+FN).