Researchers ran an advertisement in a campus newspaper asking for sedentary volunteers who were willing to begin an exercise program. The volunteers were allowed to choose which of three programs they preferred: jogging, swimming, or aerobic dance. After 5 weeks on the exercise programs, weight loss was measured. The joggers lost the most weight, and the researchers announced that jogging was better for losing weight than either swimming or aerobic dance. Refer to Exercise 10. What are the explanatory and response variables