A tax consultant studied the current relation between selling price and assessed valuation of one-family residential dwellings in a large tax district by obtaining data for a random sample of 16 recent sales transactions of one-family dwellings located on corner lots and for a random sample of 48 recent sales of one-family dwellings not located on corner lots. Both selling price (Y) and assessed valuation (X1) are expressed in thousand dollars, whereas lot location (X2) is coded 1 for corner lots and 0 for non-corner lots. y x1 x2
78.8 76.4 0
73.8 74.3 0
64.6 69.6 0
76.2 73.6 0
87.2 76.8 0
70.6 72.7 1
86 79.2 0
83.1 75.6 0
94.5 78.1 0
71.2 76.9 1
64.3 68.5 0
73.1 73.2 0
96.8 77.5 0
82.4 76.2 0
81.6 75.1 0
76.8 77 1
77.2 73 0
73.7 73 1
88.6 77.2 0
74.7 73.4 0
91.2 78.8 0
86.6 77.3 0
82.7 76.5 0
87.8 76.8 0

Required:
a. Plot the sample data for the two populations as a symbolic scatter plot. Does the regression relation appear to be the same for the two populations?
b. Test for identity of the regression functions for dwellings on corner lots and dwellings in Other locations; control the risk of Type I error at .05. State the alternatives, decision rule, and conclusion.
c. Plot the estimated regression functions for the two populations and describe the nature of the differences between them.