Effects of Prevalence on Diagnostic Tests
2x2 Table
| Breast Cancer |
Total |
||
| Positive |
Negative |
||
| Physical Examination | |||
| Positive (lump) |
8 | 99 | 107 |
| Negative (no lump) | 2 | 891 | 893 |
| Total | 10 | 990 | 1000 |
Reflection
What is the positive predictive value of a breast lump in this population?
Reflection
What is the negative predictive value in this population (i.e. the chance that a normal, lump-free exam is correct)?