Of 2, 500 people who survived a first heart attack, those who did not smoke had their first heart attack at a median age of 62. However, of those 2, 500, people who smoked two packs of cigarettes a day had their first heart attack at a median age of 51. On the basis of this information, it can be concluded that nonsmokers tend to have a first heart attack eleven years later than do people who smoke two packs of cigarettes a day.
The conclusion is incorrectly drawn from the information given because this information does not include how many of the 2,500 people studied suffered a second heart attack.