Do grumpy old men have a greater risk of having coronary heart disease than men who aren't so grumpy? Harvard Medical School researchers examined this question in a prospective observational study reported in the November 1994 issue of Circulation (Kawachi et al., 1994). For 7 years, the researchers studied men between the ages of 46 and 90. All study participants completed a survey of anger symptoms at the beginning of the study period. Among 200 men who had no anger symptoms, there were 10 cases of coronary heart disease. Among the 460 men who had the most angry symptoms there were 60 cases of coronary heart disease. (Note that 200 and 460 are totals here.)

(a) (1 point) Construct a contingency table for the relationship between degree of anger and the incidence of heart disease.

(b) (2 points) Among those with no anger symptoms, what percentage had coronary heart disease? Among those with the most anger symptoms, what percentage had coronary heart disease? Do you think that there is a difference between these groups?

(c) (2 points) Write null and alternative hypotheses about the possible relationship between the two variables.

(d) (4 points) Calculate the table of expected counts for these data.

(e) (2 points) Calculate the value of the 2 statistic for testing your null hypothesis from (a). You must show your work for full credit.

(f) (1 point) Using statistical software, compute the p-value associated with the 2 statistic from part (d). Round your answer to four decimal places.

(g) (2 points) Based on the results to (e) and (f), what can you conclude about your hypothesis from part (a)? Give an explanation in the context of this situation.