In Example 10.3.1, we saw that the purpose of a study by Jansen and Keller (A-12) was to predict the capacity to direct attention (CDA) in elderly subjects. The study collected information on 71 community-dwelling older women with normal mental status. Higher CDA scores indicate better attentional functioning. In addition to the variables age and education level, the researchers performed stepwise regression with two additional variables: IADL, a measure of activities of daily living (higher values indicate greater number of daily activities), and ADS, a measure of attentional demands (higher values indicate more attentional demands). Perform stepwise regression with the data in the following table and report your final model, p values, and conclusions.

CDA Age Edyrs IADL ADS CDA Age Edyrs IADL ADS 4.57 72 20 28 27 3.17 79 12 28 18

3:04 68 12 27 96
1:19 87 12 21 61 1.39 65 13 24 97 0.99 71 14 28 55

3:55 85 14 27 48
2:94 81 16 27 124

2:56 84 13 28 50
2:21 66 16 28 42

4:66 90 15 27 47
0:75 81 16 28 64

2:70 79 12 28 71 5.07 80 13 28 26 0.30 74 10 24 48
5:86 82 12 28 84

4:46 69 12 28 67 5.00 65 13 28 43

6:29 87 15 21 81 0.63 73 16 26 70

4:43 84 12 27 44 2.62 85 16 28 20 0.18 79 12 28 39 1.77 83 17 23 80

1:37 71 12 28 124
3:79 83 8 27 21 3.26 76 14 29 43 1.44 76 20 28 26

1:12 73 14 29 30
5:77 77 12 28 53

0:77 86 12 26 44
5:77 83 12 22 69 3.73 69 17 28 47
4:62 79 14 27 82

5:92 66 11 28 49
2:03 69 12 28 77 5.74 65 16 28 48
2:22 66 14 28 38 2.83 71 14 28 46 0.80 75 12 28 28

2:40 80 18 28 25
0:75 77 16 27 85

0:29 81 11 28 27
4:60 78 12 22 82 4.44 66 14 29 54 2.68 83 20 28 34 3.35 76 17 29 26
3:69 85 10 20 72

3:13 70 12 25 100 4.85 76 18 28 24

2:14 76 12 27 38
0:08 75 14 29 49 9.61 67 12 26 84 0.63 70 16 28 29 7.57 72 20 29 44 5.92 79 16 27 83