Sensitivity, Specificity, and Incidence

Testing, whether done in the medical field or elsewhere, generally has what is known as sensitivity and specificity. Sensitivity is the fraction of tested subjects who truly have some
characteristic that the test will say they have. Specificity is the fraction of tested subjects who truly do not have some characteristic that the test will say they do not have. This Demonstration shows how the number of true positives, false positives, false negatives, and true negatives can be calculated by using data regarding sensitivity, specificity, and the incidence in the tested population of a particular characteristic.