Principles of Public Health Exam 1

Positive predictive value and negative predictive value tell you how trustworthy a test result is in a given population. PPV is the probability that someone who tests positive actually has the disease, while NPV is the probability that someone who tests negative truly does not have the disease. These values depend on how common the disease is in the population (prevalence) as well as the test’s sensitivity and specificity. In populations with higher prevalence, PPV tends to be higher and NPV tends to be lower; with lower prevalence, the opposite happens. The correct statement captures these definitions precisely. The other statements mix up the disease status, claim independence from prevalence, or say PPV equals NPV in all tests, which isn't true.