Lecture 25

Looking at the plots of the predictors against the raw residuals tells if there is curvature but need not suggest the appropriate transformation. Looking at the partial residuals should suggest the appropriate transformation. We will look at the clear-cut example from Mendenhall and Sincich: A Second Course in Statistics, Regression Analysis, which models the price of coffee on the demand for coffee. Then we will look at the pollution data from Rice again.

demand	price	advertisement
1190	3.0	1
1033	3.2	1
897	3.4	1
789	3.6	1
706	3.8	1
595	4.0	1
512	4.2	1
433	4.4	1
395	4.6	1
304	4.8	1
243	5.0	1
1124	3.0	0
974	3.2	0
830	3.4	0
702	3.6	0
619	3.8	0
529	4.0	0
451	4.2	0
359	4.4	0
296	4.6	0
247	4.8	0
194	5.0	0

Day WindSped Temp Humidity Insolat Oxidant
1 50 77 67 78 15
2 47 80 66 77 20
3 57 75 77 73 13
4 38 72 73 69 21
5 52 71 75 78 12
6 57 74 75 80 12
7 53 78 64 75 12
8 62 82 59 78 11
9 52 82 60 75 12
10 42 82 62 58 20
11 47 82 59 76 11
12 40 80 66 76 17
13 42 81 68 71 20
14 40 85 62 74 23
15 48 82 70 73 17
16 50 79 66 72 16
17 55 72 63 69 10
18 52 72 61 57 11
19 48 76 60 74 11
20 52 77 59 72 9
21 52 73 58 67 5
22 48 68 63 30 5
23 65 67 65 23 4
24 53 71 53 72 7
25 36 75 54 78 18
26 45 81 44 81 17
27 43 84 46 78 23
28 42 83 43 78 23
29 35 87 44 77 24
30 43 92 35 79 25