Specificity (Screening and Diagnostic Testing)

Specificity is the probability that a screening or diagnostic test returns a negative result, conditioned on the person truly not having the condition being tested for: a highly specific test rarely flags a healthy person as positive, making it useful for confirming a condition when it comes back positive. It is sensitivity's counterpart, and the two are read together rather than alone, since prevalence in the tested population changes how a given sensitivity and specificity translate into the chance that a positive or negative result is actually correct.