This shiny app calculates the positive and negative predictive values for a diagnostic test with particular sensitivity and specificity. Results are produced for a range of prevalences.
Background on the relationship between positive/negative predictive value and prevalence can be found here or there is more general information on wikipedia .
Use the sliders below to change the value of the sensitivity and specificity to match your diagnostic test.
If you are looking for a more precise, or a very small, prevalence value you select a specific range for the prevalence. The calculator will split this range into 100 steps.
The plot below shows the positive and negative predictive values for a range of prevalences, based on the sensitivity and specificity shown on the sliders.
For precise values, hover over the point and a tooltip will appear.
The results are also shown in the table below. The table is sortable and searchable by prevalence.