For each problem, select the best response. (a) The Nurses' Health Study has interviewed a sample of more than 100,000 female registered nurses every two years since 1976. The study finds that " light-to-moderate drinkers had a significantly lower risk of death" than either nondrinkers or heavy drinkers. The Nursers' Health Study is .A. A. an experiment. A B. an observational study. A c. Can't tell without more information. (b) A marketing class designs two videos advertising an expensive Mercedes sports car. They test the videos by asking fellow students to view both (in random order) and say which makes them more likely to buy the car. Mercedes should be reluctant to agree that the video favored in this study will sell more cars because .A. A. results from students may not generalize to the older and richer customers who might buy a Mercedes. '5 B. the study used matched pairs design instead of a completely randomized design. .A. C. this is an observational study, not an experiment. A D. None of the above. (c) What electrical changes occur in muscles as they get tired? Student subjects hold their arms above their shoulders until they have to drop them. Meanwhile, the electrical activity in their arm muscles is measured. This is .A. A. an experiment with no control group. .A. B. a randomized comparative experiment. A C. an observational study. .A. D. None of the above. Note: You can earn partial credit on this problem. Preview My Answers Submit Answers