Sensitivity, Specificity, and Predictive Value Refresher
Measure | Description | Formula |
---|---|---|
Sensitivity | Probability that result will be positive when disease is present | TP/(TP + FN) |
Specificity | Probability that result will be negative when disease is absent | TN/(TN + FP) |
Accuracy | Number of correct findings | (TP + TN)/(TP + TN + FP + FN) |
Positive predictive value | Probability that patients with positive result truly have disease | TP/(TP + FP) |
Negative predictive value | Probability that patients with negative result do not have disease | TN/(TN+FN) |
TP = patients with positive result who have disease; FN = patients with negative result who have disease; TN = patients with negative result who do not have disease; FP = patients with positive result who do not have disease.