Suppose we are interested in investigating the relationship between high salt intake and death from cardiovascular disease (CVD). One possible study design is to identify a group of high and low-salt users then follow them over time to compare the relative frequency of CVD death in the two groups. In contrast, a less expensive study design is to look at death records, identify CVD deaths from nonCVD deaths, collect information about the dietary habits of the deceased, then compare salt intake between individuals who died of CVD versus those who died of other causes. This design is called a retrospective design. Suppose a retrospective study is done in a specic county of Massachusetts in which data are collected on men ages 5054 who died over a 1month period. Researchers reviewed the medical records of 35 men who died from CVD and 25 men who died from other causes. Of those who died from CVD, 5 had a diet with high salt intake before they died, while of those who died from other causes, 2 had a diet with high salt intake. These data are summarized in the following table. CVD Death Non-CVD Death Total High Salt Diet 7 Low Salt Diet 53 Total 60 a) Under the null hypothesis of no association, what are the expected cell counts? b) Of the 35 CVD deaths, 5 were in the high salt diet group and 30 were in the low salt diet group. Under the assumption that the marginal totals are xed, enumerate all possible sets of results (i.e., the table counts) that are more extreme than what was observed, in the same direction. c) Calculate the probability of observing each set of results from part b). d) Evaluate the statistical signicance of the observed data with a twosided alternative. Let a = 0.05. Summarize your results. e) Is relative risk an appropriate measure of association for these data? Explain your