Problem 1

15.54 The Tire Rack, America's leading online distributor of tires and wheels, conducts extensive testing to provide customers with products that are right for their vehicle, driving style, and driving conditions. In addition, the Tire Rack maintains an independent consumer survey to help drivers help each other by sharing their long-term tire experiences. The following data show survey ratings (1 to 10 scale with 10 the highest rating) for 18 maximum performance summer tires. The variable Steering rates the tire's steering responsiveness, Tread Wear rates quickness of wear based on the driver's expectations, and Buy Again rates the driver's overall tire satisfaction and desire to purchase the same tire again.

1. Clearly specify the dependent variable and the independent variables, and develop an estimated regression equation that can be used to predict the Buy Again rating given the Steering rating and the Tread Wear rating.
2. What are the estimates for parameters of the independent variables?
3. What are the p-values of the t tests for the independent variables?
4. What is the p-value of the F test?
5. At the .05 level, are there significant relationship between the dependent variable and the independent variables?
6. What is the multiple coefficient of determination?
7. What is the adjusted multiple coefficient of determination?
8. Interpret the results.

Tire Steering Tread Wear Buy Again Goodyear Assurance TripleTred 8.9 8.5 8.1 Michelin HydroEdge 8.9 9.0 8.3 Michelin Harmony 8.3 8.8 8.2 Dunlop SP 60 8.2 8.5 7.9 Goodyear Assurance ComforTred 7.9 7.7 7.1 Yokohama Y372 8.4 8.2 8.9 Yokohama Aegis LS4 7.9 7.0 7.1 Kumho Power Star 758 7.9 7.9 8.3 Goodyear Assurance 7.6 5.8 4.5 Hankook H406 7.8 6.8 6.2 Michelin Energy LX4 7.4 5.7 4.8 Michelin MX4 7.0 6.5 5.3 Michelin Symmetry 6.9 5.7 4.2 Kumho 722 7.2 6.6 5.0 Dunlop SP 40 A/S 6.2 4.2 3.4 Bridgestone Insignia SE200 5.7 5.5 3.6 Goodyear Integrity 5.7 5.4 2.9 Dunlop SP20 FE 5.7 5.0 3.3