
| Pretest | |
| unit | % Fraction |
| Sensitivity | |
| unit | % Fraction |
| Specificity | |
| unit | % Fraction |

Positive
=
((Pretest × Sensitivity) ÷ ((Pretest × Sensitivity) + ((100 - Pretest) × (100 - Specificity)))) × 100
Negative
=
((Pretest × (100 - Sensitivity)) ÷ (((100 - Pretest) × Specificity) + (Pretest × (100 - Sensitivity)))) × 100