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 14? Explain.

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Subject Initial Terminal Subject Initial Terminal Number Weight Weight Number Weight Weight 12345 171 168 15 110 111 16 56 115 118 110 113 134 136 17 142 146 115 119 18 127 127 150 155 19 102 105 6 104 106 20 125 125 7 142 148 21 157 158 8 120 124 22 119 126 9 144 148 23 113 114 10 156 154 24 120 128 11 114 114 25 135 139 12 121 123 26 148 150 13 122 126 27 110 112. 14 120 115 28 160 163