A study is done to examine whether there is an association between use of multivitamins and risk of coronary artery disease (heart attacks). Compared to people who do not take vitamins, individuals who take daily multivitamins have a risk ratio of 0.7.

Which of the following is a correct interpretation of this finding?



A cohort study is conducted to investigate whether there is an association between alcohol consumption and esophageal cancer. The investigators group the subjects into four risk categories: a) non-drinkers, b) less than two drinks per week, c) less than two drinks per day, d) greater than two drinks per day.

Which of the following statements is true regarding calculation of the strength of association in this study?



In order to discuss the EXCESS RISK caused by a risk factor which of the following should be used?



When public health officials are interested in determining the number of cases which could possibly be prevented by eliminating a risk factor, which measure of association would they be interested in?