What does specificity refer to in diagnostic testing?

Specificity in diagnostic testing specifically refers to the ability of a test to correctly identify individuals who do not have a particular disease. It is defined as the proportion of true negatives among all those who do not have the disease. This means that a highly specific test will yield a low false-positive rate, accurately reflecting that when the test is negative, it is indeed indicating the absence of the disease.

This concept is crucial in clinical settings because it helps ensure that individuals who are not affected by a disease are not incorrectly diagnosed or subject to unnecessary treatments and interventions. In contrast, the accuracy of predicting positive outcomes, the rate of false positives, and the proportion of people who test positive for the disease are related but distinct concepts that focus on other aspects of test performance.