A study by Doll et al. (1994) examined the relationship between moderate intake of alcohol and the risk of heart disease. In all, 410 men (209 “abstainers” and 201 “moderate drinkers”) were observed over a period of 10 years, and the number experiencing cardiac arrest over this period was recorded and compared with drinking habits. All men were 40 years of age at the start of the experiment. By the end of the experiment, 12 abstainers had experienced cardiac arrest and 9 moderate drinkers had experienced cardiac arrest.

a. Test whether the relative frequency of cardiac arrest was different in the two groups of men.

b. Assume that you were unable to reject the null hypothesis in part (a). Would this imply that drinking has no effect on the risk of cardiac arrest? Why or why not?