A 20-year study of British male physicians (R. Doll and R. Peto, British Med. J., 2: 1525-1536 (1976)) noted that the proportion who died from lung cancer was .00140 per year for cigarette smokers and .00010 per year for nonsmokers. The proportion who died from heart disease was .00669 for smokers and .00413 for nonsmokers.

a. Describe the association of smoking with lung cancer and with heart disease, using the difference of proportions, the relative risk, and the odds ratio. Interpret.

b. Which response is more strongly related to cigarette smoking in terms of the reduction in deaths that could occur with an absence of smoking?