Reference standard | Outcome | Test measures | ||

Positive | Negative | |||

Diagnostic algorithm | ||||

Positive | True positives correctly identified (A) | False positives (B) | Total identified as positive | PPV=A/(A+B) |

Negative | False negatives (C) | True negatives correctly identified (D) | Total identified as negative | NPV=D/(C+D) |

Outcome | True positives | True negatives | ||

Test measures | Sensitivity=A/(A+C) | Specificity=D/(B+D) |