screening_prob_soln

screening_prob_soln - sketch of solutions to screening...

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sketch of solutions to screening problems drawing the corresponding trees will be helpful! Breast cancer and mammograms from Principles of Biostatistics, Marcello Pagano and Kimberlee Gauvreau, Duxbury Suppose that the sensitivity of a mammogram, a screening test for detecting breast cancer, is .85 and its specificity is .80. That is, using the notation BC + for the event that a woman has breast cancer and M + for the event that the mammogram is positive, the sensitivity is P { M + | BC + } = .85 the specificity is P {M - | BC - } = .80 using the rule from the probability summary P(A | C) + P(A c | C) = 1 P { M - | BC + } = 1 - .85 = .15 P {M + | BC - } = 1 - .80 = .20 Suppose that this test is used on a population of women under age 45 years, and that it is known that the probability that a woman selected at random from this population has breast cancer is .0025. Find P {BC + | M + } the predictive value positive P {BC + | M + } = P {BC + and M + } / P { M + } the numerator P {BC + and
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screening_prob_soln - sketch of solutions to screening...

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