Table 2. Sensitivity and Specificity of Clinical Findings: Red Eye from 2 Feet, Any Discharge, and a Combination of Red Eye or Any Discharge.
| Formulae | Red Eye | Any Discharge | Red Eye or Any Discharge | |
|---|---|---|---|---|
| Sensitivity | TP/(TP + FN) | 0.96 | 0.88 | 1.00 |
| Specificity | TN/(TN + FP) | 0.35 | 0.44 | 0.18 |
| Positive predictive value | TP/(TP + FP) | 0.52 | 0.34 | 0.47 |
| Negative predictive value | TN/(TN + FN) | 0.92 | 0.83 | 1.00 |
| Accuracy | (TN + TP)/all | 0.61 | 0.63 | 0.53 |
FN, false negative; FP, false positive; TN, true negative; TP, true positive.