Refer to Copier maintenance Problem 1.20. The observations are listed in time order. Assume that regression model (12.1) is appropriate. Test whether or not positive autocorrelation is present: use α = .01. State the alternatives, decision rule, and conclusion.

Problem 1.20

Copier maintenance. The Tri-City Office Equipment Corporation sells an imported copier on a franchise basis and performs preventive maintenance and repair service on this copier. The data below have been collected from 45 recent calls on users to perform routine preventive maintenance service; for each call, X is the number of copiers serviced and Y is the total number of minutes spent by the service person. Assume that first-order regression model (1.1) is appropriate.

a. Obtain the estimated regression function.

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

c. Interpret b_o in your estimated regression function. Does b_o provide any relevant information here? Explain.

d. Obtain a point estimate of the mean service time when X = 5 copiers are serviced.