# PSA is a screening test used to detect patients who may be at a higher risk of developing prostate cancer.

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PSA is a screening test used to detect patients who may be at a higher risk of developing prostate cancer. A PSA value > 4.0 ng/mL is typically a value that physicians would use to further recommend a prostate biopsy. Statistics show that only 25% of men with a PSA > 4.0 actually have prostate cancer. The cost of a prostate biopsy is expensive but the cost of missing a case could be fatal. a. Based on the above information, what factors would you consider when recommending a PSA screening test to a patient? Would you err on the side of having a false positive or false negative? Explain your rationale. b. Based on the above information, what is the false positive rate for a PSA test? c. Suppose you sample 35 men with prostate cancer and 35 without prostate cancer. Among the 35 with prostate cancer, 7 have a PSA > 4.0. Among the 35 without prostate cancer, 3 have a PSA greater than 4.0. Based on this data, calculate the sensitivity, specificity, positive predictive value and negative predictive value. HINT – It may be helpful to draw out the 2 by 2 grid. Show calculations