in the 1980’s, a clinical trial was conducted to determine if taking an aspirin daily reduced the incidence of heart attacks. of 22,071 medical doctors participating in the study, 11,037 were randomly assigned to take aspirin and 11,034 were randomly assigned to the placebo group. doctors in this group were given a sugar pill disguised to look like aspirin. after six months, the proportion of heart attacks in the two groups was compared. only 104 doctors who took aspirin had a heart attack, whereas 189 who received the placebo had a heart attack. can we conclude from this study that taking aspirin reduced the chance of having a heart attack? the purpose of this study was to determine whether taking an aspirin daily reduces the proportion of heart attacks.