# Question

The Texas Transportation Institute (tti.tamu.edu) studies traffic delays. They estimate that in the year 2011, 498 urban areas experienced 5.5 billion vehicle hours of delay, resulting in 2.9 billion gallons of wasted fuel and $121 billion in lost productivity and fuel costs. That’s about 0.7% of the nation’s GDP that year. Data the institute published for the year 2001 include information on the Total Delay per Person (hours per year spent delayed by traffic), the Average Arterial Road Speed (mph), the Average Highway Road Speed (mph), and the Size of the city (small, medium, large, very large). The regression model based on these variables looks like this. The variables Small, Large, and Very Large are indicators constructed to be 1 for cities of the named size and 0 otherwise.

a) Why is there no coefficient for Medium?

b) Explain how the coefficients of Small, Large, and Very Large account for the size of the city in this model.

a) Why is there no coefficient for Medium?

b) Explain how the coefficients of Small, Large, and Very Large account for the size of the city in this model.

## Answer to relevant Questions

Here’s a scatterplot of the residuals against predicted values for the regression model found in Exercise. a) The two extraordinary points in the lower right are Reggio’s and Michelina’s, two gourmet brands. Interpret ...In Exercise 19, we raised questions about two gourmet pizzas. After removing them, the resulting regression looks like this. A plot of the residuals against the predicted values for this regression looks like this. It has ...Do movies of different types have different rates of return on their budgets? Here’s a scatterplot of Gross Revenue in US ($M) vs. Budget ($M) for recent movies whose MPAA Rating is either PG (blue) or R (red): a) Why ...Here is the regression for Exercise 3 with an indicator variable: Dependent variable is: US Gross($M) R-squared = 0.193, Adjusted R-squared: 0.166 s = 37.01 with 62 - 3 = 59 degrees of freedom a) Write out the regression ...An Additive regression model for the Apple prices is: a) What is the name for the kind of variable called Jan in this model? b) Why is there no predictor variable for December?Post your question

0