Screening – Chapter 16 – Homework AssignmentSuppose that 50,000 women who have never had a breast cancer diagnosis are available and willing to participate in a new screening program of computerized digital mammography. One thousand one hundred thirty-two (1132) women had a positive screening test. All of these positive women had a breast biopsy, and 136 were diagnosed with breast cancer. Of the 48,868 who screened “negative” on the test, 24 were in fact in the detectable pre-clinical phase. This was determined by following these women and observing that all 24 were diagnosed with breast cancer within one year of the screening test. 1. What is the prevalence of the detectable pre-clinical phase of breast cancer in this population?a. 136/50,000b. 160/50,000c. 1,132/50,0002. What is the sensitivity of this new screening test?a. 12%b. 85%c. 98%d. 99.9%3. What is the specificity of this new screening test?a. 12%b. 85%c. 98%d. 99.9%4. What is the predictive value of a positive test result for this new screening test?a. 12%b. 85%c. 98%d. 99.9%5. A colleague in another city reports that the same screening test (with the same sensitivity and specificity) is achieving a predictive value positive of only 6%. What is the explanation for this?a. The colleague is screening a higher risk population.b. The colleague is screening a lower risk population.c. The colleague is screening a larger population.d. The colleague is screening a smaller population.6. Lead time bias makes it erroneously appear that survival is better for screened versus unscreened cases.a. Trueb. False
