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health.sensitivity-specificity-PPV Calculator
Calculates sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) from a 2×2 confusion matrix, and derives likelihood ratios. Post-test probability = pre-test odds × LR+ — the likelihood ratio is the key number for updating clinical probability.
Inputs
Sensitivity Pct
Reference formula or conversion factor shown for context.
Specificity Pct
Reference formula or conversion factor shown for context.
Prevalence Pct
Reference formula or conversion factor shown for context.
Results
positive predictive value PPV
The computed numeric or monetary value.
negative predictive value NPV
The computed numeric or monetary value.
likelihood ratio positive LR+
The proportional relationship between two quantities.
likelihood ratio negative LR-
The proportional relationship between two quantities.
PPV = (Sn·P)/(Sn·P + (1-Sp)(1-P))
Sample size or count used in the calculation.
LR+ interpretation
Qualitative summary of what the computed numbers mean in practical terms.