VITAL DX v4.0 • VERIFIED QUANTITATIVE BRIEFING
Bayesian Positive Predictive Value: 80% Sens / 80% Spec / 2% Prevalence
With 80% sensitivity, 80% specificity, and 2% disease prevalence, the Positive Predictive Value (PPV) of a positive test is 7.5%.
Bayes Theorem: PPV = TP / (TP + FP) = (80% × 2%) / [(80% × 2%) + (20% × 98%)] = 7.5%.
FAQ: What is the PPV when sensitivity is 80%, specificity is 80%, and prevalence is 2%?
The Positive Predictive Value (PPV) is 7.5%, meaning 92.5% of positive results at 2% prevalence are false positives.