Question: Refer to Original Source 10 on the CD, "Religious attendance and cause of death over 31 years." Table 2 in the article provides 95% confidence intervals for the relative risk of death by various causes for those who attend religious services less than weekly versus weekly. (The relative risk is called "relative hazard" in the article and adjustments already have been made for some confounding factors such as age.)

a. Report the 95% confidence interval for "All Causes." Explain what it means in a few sentences that would be understood by someone with no training in statistics. Make sure your explanation applies to the correct population.

b. What value of relative risk would indicate equal risk for those who attend and do not attend religious services at least weekly?

c. Confidence intervals are given for the relative risk of death for five specific causes of death (circulatory, cancer, digestive, respiratory and external). For which of these causes can it be concluded that the risk of death in the population is lower for those who attend religious services at least weekly? Explain what criterion you need to determine your answer.

d. Read the article to determine whether the results are based on an observational study or a randomized experiment. Using that information, explain whether it can be concluded that attending religious services at least weekly causes the risk of death to change, for causes of death for which the confidence interval indicates there is such a change.