A test has high false positive rate in a community.True is
Low prevalence Repeat form Nov 08 "In a population with a low prevalence of a paicular disease, it is likely that most of the positive results in a screening program for that disease would be falsely positive."- Epidemiology, biostatistics, and preventive medicine By James F. Jekel, David L. Katz, Joann G. Elmore 2/e p120 "In a high-prevalence population, the absolute number of false-positives is small in comparison with the absolute numbers of true positives. In a low-prevalence population, the absolute number of false-positives is large in comparison with the absolute number of true positives." -The basic science of oncology By Ian Tannock 4/e p486, 487 The no. of false positive varies inversely with the prevalence of disease in population. This means that when the same test is applied to two populations with differing prevalence; false positive cases would be more in the population with low prevalence and false positive cases would be low in the population with high prevalence. Also Note: Sensitivity and specificity are characteristic of a paicular test and do not depend on the prevalence of disease in the population being tested. The positive predictive value and the negative predictive value depend on characteristics of both the test (sensitivity and specificity) and the population being tested (prevalence of disease). The positive predictive value is directly propoional to the prevalence. The negative predictive value is inversely propoional to prevalence. As the prevalence of disease declines, the positive predictive value of the test declines and the negative predictive value increases.
High specificity
High sensitivity
High prevalence
Low prevalence