Highway crash data analysis. Researchers at Montana State University have written a tutorial on an empirical method for analyzing before and after highway crash data (Montana Department of Transportation, Research Report, May 2004). The initial step in the methodology is to develop a Safety Performance
Interstate Highways
Noninterstate Highways
- a. Give the least squares prediction equation for the interstate highway model.
- b. Give practical interpretations of the β estimates, part a.
- c. Refer to part a. Find a 99% confidence interval for β1 and interpret the result.
- d. Refer to part a. Find a 99% confidence interval for β2 and interpret the result.
- e. Repeat parts a-d for the noninterstate highway model.
- f. Write a first-order model for E(y) as a function of x1 and x2 that allows the slopes to differ depending on whether the roadway segment is Interstate or non-interstate. [Hint: Create a dummy variable for Interstate/non-interstate.]
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