The proportion with the lowest false positive rate will have the highest which measure?

The proportion with the lowest false positive rate will have the highest which measure?

• A. Sensitivity
• B. NPV
• C. PPV
• D. Specificity

Answer: (D)

The key idea is that false positive rate is the complement of specificity. Specificity is the proportion of true negatives among those without disease (TN/(TN+FP)). The false positive rate is FP/(TN+FP), which equals 1 minus specificity. So a test with the lowest false positive rate will have the highest specificity. Sensitivity cares about correctly identifying those with disease (TP/(TP+FN)) and isn’t affected by FP. PPV and NPV depend on FP and FN and on disease prevalence, so they don’t directly align with the lowest FP rate in the same way.

The key idea is that false positive rate is the complement of specificity. Specificity is the proportion of true negatives among those without disease (TN/(TN+FP)). The false positive rate is FP/(TN+FP), which equals 1 minus specificity. So a test with the lowest false positive rate will have the highest specificity.

Sensitivity cares about correctly identifying those with disease (TP/(TP+FN)) and isn’t affected by FP. PPV and NPV depend on FP and FN and on disease prevalence, so they don’t directly align with the lowest FP rate in the same way.