Two cohort studies were conducted. The first involved an assessment of
the relationship between cigarette smoking and incidence of lung cancer.
For cigarette smokers, the lung cancer incidence rate was $I_e = 200$ per
100,000. For nonsmokers, the lung cancer incidence rate was $I_o = 25$ per
100,000. The lung cancer incidence rate in the entire population was $I_t = $
100 per 100,000. The second study involved an assessment of the
relationship between cigarette smoking and incidence of coronary heart
disease. For cigarette smokers, the coronary heart disease incidence rate
was $I_e = 500$ per 100,000. For nonsmokers, it was $I_o = 250$ per 100,000.
In the overall population, the coronary heart disease rate was $I_t = 300$.
From the data involving cigarette smoking and lung cancer incidence,
what are the attributable risk and the attributable risk percent? Interpret
the result.
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