A Swedish study used 1360 patients who had suffered a stroke. The study randomly assigned each subject to an aspirin treatment or a placebo treatment. In this study heart attacks were suffered by 28 of the 684 subjects taking placebo and 18 of the 676 subjects taking aspirin.
a. Report the data in the form of a 2 × 2 contingency table.
b. Show how to carry out all five steps of the null hypothesis that having a heart attack is not associated with whether one takes placebo or aspirin. (You should get a chi-squared statistic equal to 2.1.) Interpret.