The
positive and negative predictive values (
PPV and
NPV respectively) are the proportions of positive and negative results in
statistics and
diagnostic tests that are
true positive and
true negative results. The PPV and NPV describe the performance of a diagnostic test or other statistical measure. A high result can be interpreted as indicating the accuracy of such a statistic. The PPV and NPV are not intrinsic to the test; they depend also on the
prevalence. The PPV can be derived using
Bayes' theorem.