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Diagnostic test evaluation and comparison

Positive and Negative Predictive Values for a test

        Sensitivity Specificity


Use this to calculate the positive and negative predictive values for a test of known sensitivity and specificity for a range of prior probabilities of infection.


  • - Test unit sensitivity;
  • - Test unit specificity; and
  • - Prior probability of infection.


  • - Positive (PPV) and negative (NPV) predictive values for given inputs; and
  • - Table and plot of PPV and NPV for given sensitivity and specificity values and varying prior probability of infection.

This site was created by Ausvet with funding from a range of sources. It provides a range of epidemiological tools for the use of researchers and epidemiologists. Please submit any comments, questions or suggestions here.