400 patients are enrolled in a study to evaluate the accurac

400 patients are enrolled in a study to evaluate the accuracy of a test for diabetes disease. 200 of the patients were diagnosed with diabetes. 160 of the patients with diabetes had a positive test as did 10 of the patients without diabetes. What is the probability (i.e., PPV) that a patient has diabetes given that he/she tested positive on a screening test?

0.94

0.80

0.83

0.95

Disease Test I Diabetes No Diabetes Total + 160 I 40 10 190 I 170 I 230 Total 200 200 400

Solution

P[patient has diabetes given that he/she tested positive on a screening test]=P[patient has diabetes and tested positive on a screening test]/P[tested positive on a screening test]=(160/400)/(170/400)=0.9411=0.94 [rounded of to two decimal] [answer]