The headline in an article in the Sacramento Bee read "Firing someone? Risk of heart attack doubles" (Haney, 1998). The article explained that "between 1989 and 1994, doctors interviewed 791 working people who had just undergone heart attacks about what they had done recently. The researchers concluded that firing someone or having a high-stakes deadline doubled the usual risk of a heart attack during the following week. . . . For a healthy 50-year-old man or a healthy 60-year-old woman, the risk of a heart attack in any given hour without any trigger is about 1 in a million."
a. Refer to Chapter 5. What type of study is this?

b. Refer to the reasons for relationships listed in Section 11.3. Which do you think is the most likely explanation for the relationship found between firing someone and having a heart attack? Do you think the headline for this article was appropriate? Explain.

c. Assuming the relationship is indeed as stated in the article, write sentences that could be understood by someone with no training in statistics, giving each of the following for this example:

i. The odds ratio
ii. Increased risk
iii. Relative risk