The administrator of the National Highway Traffic Safety Administration (NHTSA) wants to know if the different types of vehicles in a state have a relationship to the highway death rate in the state. She has asked you to develop multiple regression analyses to determine if the average vehicle weight, the percentage of imported cars, the percentage of light trucks, and the average car age are related to crash deaths in automobiles and pickups. The data for the analysis are located in the data file named Vehicle Travel State. A description of the variables is contained in the Chapter 11 appendix.
a. Prepare a correlation matrix for crash deaths and the predictor variables. Note the simple relationships between crash deaths and the predictor variables. In addition, indicate any potential multicollinearity problems between the predictor variables.
b. Prepare a multiple regression analysis of crash deaths on the potential predictor variables. Remove any nonsignificant predictor variables, one at a time, from the regression model. Indicate your best final model.
c. State the conclusions from your analysis and discuss the conditional importance of the variables in terms of their relationship to crash deaths.