Calculation practice: relative risk. Wilson et al. (2011) followed a set of male health professionals for 20 years. Of all the men in the study, 7890 drank no coffee and 2492 drank on average more than six cups per day. In the “no-coffee” group, 122 developed advanced prostate cancer during the course of the study, and 19 in the “high-coffee” group did.

a. Create a contingency table for these data. Follow the convention recommended in Chapter 2: the explanatory variable is in the columns and the response variable is in the rows. What association is suggested?

b. What is the estimated probability of advanced prostate cancer for the high-coffee group (i.e., what is the risk of advanced prostate cancer for men who drink more than six cups of coffee per day)?

c. What is the estimated probability of advanced prostate cancer for the no-coffee group (i.e., what is the risk of advanced prostate cancer for non–coffee drinkers)?

d. What is the relative risk of advanced prostate cancer, comparing the treatment (high Coffee) and control (no-coffee) groups?