To refine the experiment described in Exercise 16.15, a psychologist added an additional set of households to each group. This group had a special meter installed to show them exactly how fast their...

To refine the experiment described in Exercise 16.15, a psychologist added an additional set of households to each group. This group had a special meter installed to show them exactly how fast their electric bill was increasing. (The amount-to-date was displayed on the meter.) The data follow; the nonmetered data are the same as those in Exercise 16.15.

a. Run the analysis of covariance on these data—after first checking the assumption of homogeneity of regression.

b. Draw the appropriate conclusions.