Question

We will choose SBP as the response. The two variables QUET and SMK will be considered.

a. Define a single multiple regression model (Hint: you need put these two variables and also don’t forget the interaction).

b. Using SAS to estimate this model; Write out the regression lines for smokers and nonsmokers. Are there any differences with the previous two lines from question 2?

c. Does the effect of QUET on the SBY depend on the status of smoking? You need to write the hypotheses, report SAS output and show your conclusion.

d. Assuming that the interaction is not significant, for every QUET, does the smoking status will cause any difference in SBY? Set up appropriate hypotheses and report your conclusion.

e. Applying residuals analysis to see any possible pitfalls for the model.

1 135 2.876 45 0
2 122 3.251 41 0
3 130 3.100 49 0
4 148 3.768 52 0
5 146 2.979 54 1
6 129 2.790 47 1
7 162 3.668 60 1
8 160 3.612 48 1
9 144 2.368 44 1
10 180 4.637 64 1
11 166 3.877 59 1
12 138 4.032 51 1
13 152 4.116 64 0
14 138 3.673 56 0
15 140 3.562 54 1
16 134 2.998 50 1
17 145 3.360 49 1
18 142 3.024 46 1
19 135 3.171 57 0
20 142 3.401 56 0
21 150 3.628 56 1
22 144 3.751 58 0
23 137 3.296 53 0
24 132 3.210 50 0
25 149 3.301 54 1
26 132 3.017 48 1
27 120 2.789 43 0
28 126 2.956 43 1
29 161 3.800 63 0
30 170 4.132 63 1
31 152 3.962 62 0
32 164 4.010 65 0

Answer 1