<prompt> 300 diseased people were made to undergo a test of which only 60 were positive. 40 people were found to be false positive for the test. The positive predictive value of the test is:401006010040300240300  <response>: Ans: b 60100Ref: Park, 20th ed. Pg. 126 19 ed., Pg. 119Screening test resultsDiagnosisTotalDiseasedNot diseasedPositiveNegativea True positivec False negativeb False positived True negativeabcdTotalacbdabcdSensitivity a ac x 1 XSpecificity d bd x 1 MPredictive value of positive test a ab x 100Predictive value of a negative test d cd x 100Percentage of false negatives c ac x 100Percentage of false positives b bd x 100Sensitivity is the ability of a test to identify correctly all those who have the disease that is true positive. A screening test which is very sensitive has few false negatives.Specificity is the ability of a test to identify correctly those who do not have the disease that is true negatives. A screening test which is very specific has few false positives. 