The Department of Transportation wishes to know if states with a larger percentage of urban population have higher automobile and pickup crash death rates. In addition, it wants to know if the variable average speed on rural roads or the variable percentage of rural roads that are surfaced is conditionally related to crash death rates, given percentage of urban population. Data for this study are included in the file Vehicle Travel State; the variables are defined in the Chapter 11 appendix.
a. Prepare a correlation matrix and descriptive statistics for crash deaths and the potential predictor variables.
b. Prepare a multiple regression analysis of crash deaths on the potential predictor variables. Determine which of the variables should be retained in the regression model because they have a conditionally significant relationship.
c. State the results of your analysis in terms of your final regression model. Indicate which variables are conditionally significant.