Freshman 15. Cornell Professor of Nutrition David Levitsky recruited students from two large sections of an introductory health course to test the validity of the “Freshman 15” theory that students gain 15 pounds their first year. Although they were volunteers, they appeared to match the rest of the freshman class in terms of demographic variables such as sex and ethnicity. The students were weighed during the first week of the semester, then again 12 weeks later.
a) Use a Wilcoxon signed-rank test to test whether these students’ weights changed. State your hypotheses, check conditions, and complete the test (with technology).
b) Would you prefer the nonparametric test, or the paired t-test asked for in Chapter 13? Explain.
