Anger and heart disease. A nonexperimental study looked at whether people who angered easily were more likely to develop coronary heart disease than those who angered less easily.

Spielberger anger scale scores were classified into low, moderate, and high categories. Individuals were followed for up to 72 months

(median follow-up time: 53 months). Table 18.9 shows crosstabulated results for acute and fatal coronary incidents. Calculate incidence proportions for each group. Describe the relationship between angering easily and coronary heart disease.