The following data represent more extended measurements of monthly water usage at the plant referred to in Exercise 14.98 over a period of 20 months:

(a) Use an appropriate computer program to fit a linear surface to these data.
(b) Use a computer program to make a normal-scores plot of the residuals. Does the assumption of normality appear to be satisfied at least approximately?
(c) Plot the residuals against and determine whether the pattern is random.
(d) Check for excessive multicollinearity among the independent variables.

Transcribed Image Text:

8118101272939 2 low 70 68 66 58 82 44 61 44 59 62 54 69 58 64 51 36 56 85 49 64 1 e x -76658 46456 5 6 5 6 5 3 5 8 46 duc 08 9 1 1 1 4 1 2 1 1 514 70 07 97 98 96 32 84 8734941261514077862 091406982180870999 | 09 28 59 23 88 22 12 S4 36 60 47 78 31 17 17 02 51 57 21 80 2 5 7 5 0 2 4 4 1 3 0 7 1 9 2379 ter-26 2 2 2 3 2 2 2 2 2 2 2 2 1 2 1 2 2 1 1