The probability that an individual with a positive test for a disease actually has it. A high positive predictive value indicates that the patient who has a positive test result probably has the disease.
The probability that a subject has the disease when the test result is positive. Synonyms include predictive value positive. Positive predictive value = a/m1 = TP/(TP+FP). By application of Bayes' Rule, the positive predictive value also can be defined as a function of pretest probability of disease (p), sensitivity, and specificity: positive predictive value = [(p . sensitivity)/[p . sensitivity + (1-p) . (1- specificity)].
The positive predictive value is the proportion of patients with positive test results who are correctly diagnosed. It is considered the physician's gold standard, as it reflects the probability that a positive test reflects the underlying condition being tested for.