11.10 It has been noted that metal workers have an increased risk for cancer
of the internal nose and paranasal sinuses, perhaps as a result of expo-
sure to cutting oils. A study was conducted to see whether this particu-
lar exposure also increases the risk for squamous cell carcinoma of the
scrotum (Rousch et al., 1982). Cases included all 45 squamous cell car-
cinomas of the scrotum diagnosed in Connecticut residents from 1955
to 1973, as obtained from the Connecticut Tumor Registry. Matched
controls were selected for each case based on the age at death (within
eight years), year of death (within three years), and number of jobs as
obtained from combined death certificate and directory sources. An
occupational indicator of metal worker (yes/no) was evaluated as the
possible risk factor in this study; results are shown in Table E11.10.
TABLE E11.10
Controls
Cases Yes No
Yes 2 26
No 5 12(a)Find a 95% confidence interval for the odds ratio measuring the
strength of the relationship between the disease and the exposure.
(b)Test for the independence between the disease and the exposure.11.11 Ninety-eight heterosexual couples, at least one of whom was HIV in-
fected, were enrolled in an HIV transmission study and interviewed
about sexual behavior (Padian, 1990). Table E11.11 provides a sum-
mary of condom use reported by heterosexual partners. Test to com-
pare the reporting results between men and women.
TABLE E11.11
Man
Woman Ever Never Total
Ever 45 6 51
Never 7 40 47
Total 52 46 9811.12 A matched case–control study was conducted to evaluate the cumula-
tive e¤ects of acrylate and methacrylate vapors on olfactory function
(Schwarts et al., 1989). Cases were defined as scoring at or below the
10th percentile on the UPSIT (University of Pennsylvania Smell Iden-
tification Test; Table E11.12).
434 ANALYSIS OF SURVIVAL DATA