People who get angry easily tend to have more heart disease. That's the conclusion of a study that followed a random sample of 12,986 people from three locations for about four years. All subjects were free of heart disease at the beginning of the study. The subjects took the Spielberger Trait Anger Scale test, which measures how prone a person is to sudden anger. Here are data for the 8474 people in the sample who had normal blood pressure. CHD stands for "coronary heart disease." This includes people who had heart attacks and those who needed medical treatment for heart disease.

Low anger Moderate anger High anger Total
CHD 53 110 27 190
No CHD 3057 4621 606 8284
Total 3110 4731 633 8474

Do these data support the study's conclusion about the relationship between anger and heart disease? Follow the four-step process in your answer.

1. State: Which of the following statements best describes the question we are trying to answer?
A. Is it possible to reduce heart disease by managing stress and anger levels?
B. Do people who tend to get angry easily also suffer from more heart disease?
C. After contracting heart disease, do people get angry more easily?
D. Would people who suffer from heart disease benefit from learning to control their anger?

2. Formulate: Which of the following techniques should we use to find the answer?
A. Calculate the total number of people at each anger level, and then for each anger level, find the relative proportion of people who have CHD.
B. Calculate the conditional distribution of anger level given CHD.
C. Calculate the total number of people who have CHD and compare this to the total number of people who have a high anger level.
D. Calculate the total number of people who have CHD and then find the relative proportions of such people that also have a high anger level.

3. Solve: Calculate your distribution and plot it using a bar graph.

4. CONCLUDE: Which of the following statements best describes the conclusion we can draw based on our analysis?
A. The study found that as anger level increased, so did the likelihood of suffering from CHD.
B. Surprisingly, people with moderate anger levels had the most CHD.
C. Controlling anger levels is an effective way of reducing the risk of CHD.
D. Once people suffer from CHD they get more irritable, and their anger levels rise.