Interpretation of laboratory tests using a programmable hand-held calculator: calculation of posterior probability and relative risk on the basis of prior probability and sensitivity, specificity and result of the test.

A program is presented for the Hewlett-Packard HP- 41C programmable hand-held calculator that calculates the posterior probability and relative risk of an event (e.g. a disease) on the basis of prior probability (prevalence) and sensitivity, specificity and result of the test.