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 sensitivity specificity  

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55 year old man visits his physician with urinary complaints. Examination finds a 1-cm nodule on his prostate gland. Physician orders a PSA serum test. By common standards, a PSA more than 4ng/ml is considered abnormal. Using this standard, this test has a sensitivity of 80% and specificity of 90%. A recent epidemiologic article found that in a cross-sectional study, 10% of men of this age group have prostate cancer. The result on the patient's PSA is 7ng/ml. What is the best estimate of the likelihood that this man actually has prostate cancer?

a) 13%
b) 25%
c) 36%
d) 47%
e) 58%
f) 69%
g) 72%
h) 81%

ANS. 47%... HOW to calculate?????


positive predivtive value

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