Which statement about predictive value is correct?
1Predictive value is independent of disease prevalence
2Positive predictive value decreases as disease prevalence decreases✓ 정답
3Predictive value depends only on the analytical method used
4Predictive value and sensitivity are the same measurement
해설
Sensitivity and specificity are properties of the test itself, whereas predictive values depend on prevalence. In a low-prevalence population the positive predictive value falls and false positives increase, even with the same test. This is the central concept in interpreting screening tests.