<prompt> Probability that a person out of those tested positive on a screening test has in fact the disease is known asSensitivitySpecificityPositive predictive valueNegative predictive value  <response>: Sensitivity Ability of test to identify correctly all those who have the disease, that is true positive. Specificity Ability of test to identify correctly all those who dont have the disease, that is true negative. Positive predictive value Probability that subjects with a positive screening test truly have the disease. Negative predictive value Probability that subjects with a negative screening test truly dont have the disease. Screening test results by Diagnosis Screening test results Diagnosis Total Positive a True - positive b False-positive ab Negative c False - negative d True - negative c d Total ac bd abcd Sensitivity aa c x 100 Specificity dbd x 100 Positive Predictive Value aa b x 100 Negative Predictive Value dc d x 100 