<prompt> True positive cases are detected bySpecificitySensitivityPositive predictive valueNegative predictive value  <response>: Ans. b Sensitivity. Ref. Park, PSM, 17thpg. 112TERMDEFINATIONSensitivityThe probability that a person who actually has the disease of interest will have a positive abnormal test result. In clinical practice sensitivity is inversely proportional to specificity.SpecificityThe probability that a person who actually does not have the disease of interest will have a negative normal test result.PrevalenceThe proportion of persons in a given population who have a particular disease at a point or interval of time.False-positiveA test result that is normal positive despite the true absence of the disease of interest or a study result that incorrectly suggests an effect, when in truth, the purported effect does not exist see also Type 1 error.True-negativeA test result that is normal negative when the disease of interest is actually absent.True-positiveA test result that is abnormal positive when the disease of interest is actually present.False-negativeA test result that is normal negative despite the true presence of a particular disease or a study result that incorrectly fails to identify a true effect see also Type II error. Does not have the disease of interest.Positive predictive valueThe probability that a person with a positive abnormal test result actually has the disease of interestNegative predictive valueThe probability that a person with a negative normal test result actually. Screening test resultsDiagnosis diseasedNot diseasedTotalPositiveatrue positivebfalse positivea bNegativecffalse neg.dtrue neg.CdTotalacbdabcda Sensitivity aac x 100b Specificity dbd x 100c Predictive value of a positive test aab x 100d Predictive value of a neg. test dcd x 100e Percentage of false neg. cac x 100f Percentage of false positive bbd x 100 