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Predictive powers of a test with 80% sensitivity and 99% specificity (5% prevalence).
| Test result (80% sensitivity and 99% specificity) | People truly with disease | People truly without disease | Totals |
|---|---|---|---|
| Positive | 4000 (A) | 950 (B) | 4950 |
| Negative | 1000 (C) | 94,050 (D) | 95,050 |
| Total | 5000 | 95,000 | 100,000 |
Predictive value of a positive test: A/A + B = 80.8%.
Predictive value of a negative test: D/D + C = 98.9%.
