The Physicians' Health Study was a randomized clinical trial, one goal of which was to assess the effect of aspirin in preventing myocardial infarction (MI). Participants were 22,000 male physicians ages 40-84 and free of cardiovascular disease in 1982. The physicians were randomized to either active aspirin (one white pill containing 325 mg of aspirin taken every other day) or aspirin placebo (one white placebo pill taken every other day). Suppose we assume that the incidence of MI is 0.005 per year among participants who actually take placebo and that aspirin prevents 20% of MIs. How many participants need to be enrolled in each group to have an **80%** chance of detecting a significant difference using a **one-sided test** with $\alpha=0.05$ if **compliance is perfect**?
The Physicians' Health Study was a randomized clinical trial, one goal of which was to assess the effect of aspirin in preventing myocardial infarction (MI). Participants were 22,000 male physicians ages 40-84 and free of cardiovascular disease in 1982. The physicians were randomized to either active aspirin (one white pill containing 325 mg of aspirin taken every other day) or aspirin placebo (one white placebo pill taken every other day).
Suppose we assume that the incidence of MI is 0.005 per year among participants who actually take placebo and that aspirin prevents 20% of MIs.
How many participants need to be enrolled in each group to have an **80%** chance of detecting a significant difference using a **one-sided test** with $\alpha=0.05$ if **compliance is perfect**?
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