Effects of an appetite suppressant. Subject with preexisting cardiovascular symptoms who were receiving sibutramine, an apperite suppressant, were found to be at increased risk of cardiovascular events while taking the drug. The study included 9804 overweight or obese subjects with preexisting cardiovascular disease and/or type 2 diabetes. The subjects were randomly assigned to sibutramine (4906 subjects) or a placebo (4898 subjects) in a double-blind fashion. The primary outcome measured was the occurence of any of the following events: nonfatal myocardial infraction or stroke, resuscitation after cardiac arrest, or cardiovascular death. The primary outcome was observed in 561 subjects in the sibutramine group and 490 subjects in the placebo group.

a) Find the proportion of subjects experiencing the primary outcome for both the sibutramine and placebo groups.

b) Can we safely use the large-sample confidence interval for comparing the proportions of sibutramine and placebo subjects who experienced the primary outcome? Explain.

a) Find the proportion of subjects experiencing the primary outcome for both the sibutramine and placebo groups.

b) Can we safely use the large-sample confidence interval for comparing the proportions of sibutramine and placebo subjects who experienced the primary outcome? Explain.