Solutions to Statistical Methods in the Biological and Health Sciences, by J. Susan Milton
Exercises 3.4
1. False positive rate = 12/142 = 0.085
False negative rate = 4/58 = 0.069
2a. 130/200
2b. 138/200
2c. 118/200
2d. 118/130
2e. 118/138
4. False positive rate = 23/83 = 0.277
False negative rate = 10/54 = 0.185
5. Specificity = 130/142. Want high specificity.
6. Sensitivity = 54/58. Want high sensitivity.
10. Positive predictive value = 54/66
11. Negative predictive value = 130/134
14. P(D|E) = 7/77 = 0.091
P(D|E1) = 4/232 = 0.017
So RR = 0.091/0.017 = 5.35.
15a.
Disease
Tuberculosis No Tuberculosis
Drug use 11 296 307
No drug use 35 1650 1685
Total 46 1946 1992
15b. P(D|E) = 11/307 = 0.0358
P(D|E1) = 35/1685 = 0.02077
So RR = 0.0358/0.02077 = 1.724
AIDS patients who have abused IV drugs are almost 2 times more likely to develop
tuberculosis than those who did not abuse drugs.
Solutions prepared by Laura J. Simon, Pennsylvania State University