1. This table summarizes the results from an observational study that followed a random sample of 8,474 people for about four years. All participants were free from heart disease at the beginning of the study. The variable Anger categorizes participants as Low Anger, Moderate Anger, High Anger based on the Speilberger Trait Anger Scale test, which measures how prone a person is to sudden feelings of anger. CHD stands for coronary heart disease, which is a count of the people who had heart attacks or needed medical attention for heart disease during the study.

Low Anger Moderate Anger High Anger Total

CHD 53 110 27 190

No CHD 3,057 4,621 606 8,284

Total 3,110 4,731 633 8,474

A. Calculate the "expected" counts that a chi-square test would use.

B. How do the actual counts differ from the expected counts? What kind of relationship does this suggest between anger and coronary heart disease?

C. Explain how the "expected" counts reflect the null hypothesis.