Standard 2 × 2 table used for calculating sensitivity and specificity
| Gold standard test result | New test result positive | New test result negative |
|---|---|---|
| Diseased | True positive (TP) | False negative (FN) |
| Non-diseased | False positive (FP) | True negative (TN) |
Sensitivity = TP/TP + FN.
Specificity = TN/TN + FP.
Positive predictive value = TP/TP + FP.
Negative predictive value = TN/TN + FN.
Likelihood ratio = sensitivity/1 − specificity = TP/(TP + FN)/1 − (TP/(TP + FP).