Question

2,620 men were enrolled in the study of prostate cancer and 930 of those had confirmed by biopsy prostate cancer. The sensitivity of the Prostate-Specific Antigen (PSA) test was 86% and the specificity was 33%. Calculate positive predictive value (PPV) and negative predictive value (NPV) of the PSA test given this information and interpret (explain) the results. (Show your calculations to get credit)

Answer 1

Answer:

81%

Explanation:

0.86 · 930 = 799.8 ⇒ 800 men

Other 130 men have negative PSA test

2620 - 930 = 1690 ⇒ 1690 without cancer

0.33 · 1690 = 557.8 ⇒ 558 men no cancer + negetive PSA tests

1690 - 558 = 1132

*view attachment below*

Positive perdictive value = 800/1932 = 0.42 = 42%

Negative predictive value = 558/688 = 0.81 = 81%.

The probability of not having prostate cancer among men with a negative PSA test is 81%

Sorry if it's very unclear, Good luck <3