Bayesian False Positive Probability Calculator
In laboratory testing, a **positive screen result** is not always a true diagnosis. In low-prevalence environments, even an assay with high clinical specificity will frequently yield **false positive indicators**.
This is highly critical for sensitive blood screens like HSV-2 IgG (Herpes Simplex Type 2) or Syphilis RPR. This calculator computes true-versus-false positive probability indexes using Bayesian clinical modeling.
Bayesian Positive Accuracy Calculator
Enter your positive screen index value. Calculations are performed strictly locally inside your browser.
1.8 Index
True Positive Probability
15.0%
False Positive Probability
85.0%
High Risk of False Positive
Mandatory Confirmation Protocols:
* HSV-2 IgG Indexes (1.1 to 3.5): Citing CDC guidelines, low-positive scores have up to a 90% false-positive rate due to cross-reactive proteins. **Never diagnose without confirmatory testing** (such as the HSV Western Blot at the University of Washington).
* Syphilis RPR: Standard RPR panels have high cross-reactivity with autoimmune markers. A positive RPR requires confirmatory treponemal antibody screening (FTA-ABS or TP-PA).