Homework for chapter 11
Note: This data set is from the SAS System for Mixed Models book by Littell, Milliiken, Stroup, and
Wolfinger (1996). See Chapter 3 of the book for a different analysis of the data.
From p. 88-9,
Subjects in an exercise therapy study were assigned to one of three weightlifting programs. In
the first program (RI), the number of repetitions of weightlifting was increased as the number of
subjects became stronger. In the second program (WI), the amount of weight was increased
as subjects became stronger. In the third program (CONT), subjects did not participate in
weightlifting. Strengths of the subjects were measured every other day for two weeks following
the beginning of the study.
Below is the data step to read in the data. Note that s1=strength at time 1, s2=strength at time 2,… .
data weights;
input subj program$ s1 s2 s3 s4 s5 s6 s7;
datalines;
1 CONT 85 85 86 85 87 86 87
2 CONT 80 79 79 78 78 79 78
3 CONT 78 77 77 77 76 76 77
4 CONT 84 84 85 84 83 84 85
5 CONT 80 81 80 80 79 79 80
6 CONT 76 78 77 78 78 77 74
7 CONT 79 79 80 79 80 79 81
8 CONT 76 76 76 75 75 74 74
9 CONT 77 78 78 80 80 81 80
10 CONT 79 79 79 79 77 78 79
11 CONT 81 81 80 80 80 81 82
12 CONT 77 76 77 78 77 77 77
13 CONT 82 83 83 83 84 83 83
14 CONT 84 84 83 82 81 79 78
15 CONT 79 81 81 82 82 82 80
16 CONT 79 79 78 77 77 78 78
17 CONT 83 82 83 85 84 83 82
18 CONT 78 78 79 79 78 77 77
19 CONT 80 80 79 79 80 80 80
20 CONT 78 79 80 81 80 79 80
1 RI 79 79 79 80 80 78 80
2 RI 83 83 85 85 86 87 87
3 RI 81 83 82 82 83 83 82
4 RI 81 81 81 82 82 83 81
5 RI 80 81 82 82 82 84 86
6 RI 76 76 76 76 76 76 75
7 RI 81 84 83 83 85 85 85
8 RI 77 78 79 79 81 82 81
9 RI 84 85 87 89 88 85 86
10 RI 74 75 78 78 79 78 78
11 RI 76 77 77 77 77 76 76
12 RI 84 84 86 85 86 86 86
13 RI 79 80 79 80 80 82 82
14 RI 78 78 77 76 75 75 76
15 RI 78 80 77 77 75 75 75
16 RI 84 85 85 85 85 83 82
1 WI 84 85 84 83 83 83 84
2 WI 74 75 75 76 75 76 76
3 WI 83 84 82 81 83 83 82
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