Question

Analyze the following study according to the criteria set by your instructor:
Smoking greatly increases the likelihood of premature facial wrinkling, according to University of Utah scientists reporting in the Annals of Internal Medicine. The scientists studied 109 smokers and 23 people who had never smoked, all between the ages of thirty-five and fifty-nine. The smokers had smoked three to fifty pack-years, with a pack-year equal to smoking one pack a day per year. Each subject estimated the number of hours spent in the sun, and that information was adjusted for pigmentation, place of residence, and use of sunscreen or protective clothing. The subjects temples were then photographed and the pictures evaluated by two doctors, who did not know whether the subject smoked or not. The reviewers agreed on the degree of wrinkling 81 percent of the time, and disagreements were averaged. The results were adjusted for age and pigmentation. Heavy smokers were nearly five times more likely to show excessive skin wrinkling than their nonsmoking counterparts.

Answer

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