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Homework%204%20Key-1 - Epi 231 Homework #4 Answer Key 1....

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Epi 231 Homework #4 Answer Key 1. PSA tests were given to 200 men, 100 men had prostate cancer and 100 men did not. Of the 100 men with prostate cancer, 86 had a PSA reading greater than or equal to 4. Of the 100 who did not have cancer, 33 had a PSA reading less than 4. a. Fill in the 2x2 table. PSA Greater than or Equal to 4 PSA less than 4 Total Prostate Cancer 86 14 100 Does Not have Prostate Cancer 67 33 100 b. What is the sensitivity and specificity of the test? Se = 86/100 = 86% Sp = 33/100 = 33% c. Given your answers to 1b, do you think that the PSA is an effective mass screening tool? There is a high number of false positives, which drive down the specificity. This combined with a sensitivity of .86 make this test unsuitable for mass screening. This test would be better used for targeted screening. 2. The sensitivity and specificity of the most common HIV screening tests, ELISA and the Western Blot assay, are extremely high: more than 99% for each. In 2007, the adult prevalence rate of HIV/AIDs in
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Homework%204%20Key-1 - Epi 231 Homework #4 Answer Key 1....

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