VITAL DX v4.0 • VERIFIED QUANTITATIVE BRIEFING
Bayesian Positive Predictive Value: 90% Sens / 80% Spec / 2% Prevalence
With 90% sensitivity, 80% specificity, and 2% disease prevalence, the Positive Predictive Value (PPV) of a positive test is 8.4%.
Bayes Theorem: PPV = TP / (TP + FP) = (90% × 2%) / [(90% × 2%) + (20% × 98%)] = 8.4%.
FAQ: What is the PPV when sensitivity is 90%, specificity is 80%, and prevalence is 2%?
The Positive Predictive Value (PPV) is 8.4%, meaning 91.6% of positive results at 2% prevalence are false positives.