Negative & Positive Predictive Value Equation & Calculation

PPV & NPV are used to interpret test results once you have them. For example, if your patient just received a positive HIV test result you would use the PPV to evaluate what that test result means to your patient (what the percentage is that this person actually has HIV). It is important to remember that the PPV & NPV change as prevalence changes. This makes sense, because if the prevalence of a disease increases you are g