Question

A company sells an imported copier on a franchise basis and performs preventive maintenance and repair service on this copier. The data in CH01PR20.txt have been collected from 45 recent calls on users to per- form routine preventive maintenance service. In the data, the first column (Y ) is the total number of minutes spent by the service person, and the column (X) is the number of copiers serviced. The goal is to fit a linear regressionofY onXintheformatY =β0+β1X+e.

• Obtain the estimated regression function. What is the estimate of the variance of e.

• Plot the estimated regression function and the data. How well does the estimated regression function fit the data?

• Interpret β0 in the estimated regression function. Does β0 provide any relevant information here?

• Is β1 significantly different from zero or not?

• What is the interpretation of the sign of β1?

• Include some diagnostic plots.

CH01PR20.txt is as following:

CH01PR20.txt

20 2
60 4
46 3
41 2
12 1
137 10
68 5
89 5
4 1
32 2
144 9
156 10
93 6
36 3
72 4
100 8
105 7
131 8
127 10
57 4
66 5
101 7
109 7
74 5
134 9
112 7
18 2
73 5
111 7
96 6
123 8
90 5
20 2
28 2
3 1
57 4
86 5
132 9
112 7
27 1
131 9
34 2
27 2
61 4
77 5

Answer 1