The results of this study report that 139 heart attacks developed among the aspirin users and 239 heart attacks developed in the placebo group. This was said to be a significant result in favor of aspirin as a possible preventive for heart attacks. To demonstrate this difference, place the data on heart attacks on an appropriate two-way table.
(Remember, the 22,000 participants were about evenly split between aspirin and placebo.)
What are the appropriate conditional proportions to study if we want to compare the rates of heart attacks for the two treatment groups? Do these proportions turn out to be quite different.