<unk> <unk>  - 2 The<unk>  (PPV and NPV respectively) are the proportions of<unk>  and<unk>  results in statistics and diagnostic tests that are true<unk>  and true<unk>  results, respectively. 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 (as true<unk>  rate and true<unk>  rate are); they depend also on the prevalence. Both PPV and NPV can be derived using Bayes' theorem. Although sometimes used synonymously, a<unk><unk> <unk> generally refers to what is established by control groups, while a post-test probability refers to a probability for an individual. Still, if the individual's pre-test probability of the target condition is the same as the prevalence in the control group used to establish the<unk><unk> <unk>  the two are numerically equal. In information retrieval, the PPV statistic is often called the precision.
Positive and negative predictive values
Sensitivity and specificity
Likelihood ratios in diagnostic testing
Indicative limit value
Risk of mortality
Threshold limit value
Predictive value of tests
Apparent infection rate