Refer to the Lincolnville School District bus data. First, add a variable to change the type of engine (diesel or gasoline) to a qualitative variable. If the engine type is diesel, then set the qualitative variable to 0. If the engine type is gasoline, then set the qualitative variable to 1. Develop a regression equation using statistical software with maintenance cost as the dependent variable and age, odometer miles, miles since last maintenance, and engine type as the independent variables.

picture Click here for the Excel Data File

a-1. Develop a correlation matrix. (Negative amounts should be indicated by a minus sign. Round your answers to 4 decimal places.)



a-2. Which independent variables have strong or weak correlations with the dependent variable?



a-3. Do you see any problems with multicollinearity?

multiple choice 1
Yes
No


b-1. Use a statistical software package to determine the multiple regression equation.



Use a statistical software package to determine the multiple regression equation. (Negative amounts should be indicated by a minus sign. Round your answers to 3 decimal places.)



b-2. What is the value of R2. (Round your answer to 1 decimal place.)



c-1. Develop a histogram of the residuals from the final regression equation. Which histogram is correct?



Histogram of the residuals 1 Histogram of the residuals 2 Histogram of the residuals 3
3 histograms, Histogram of the residuals 1, Histogram of the residuals 2, Histogram of the residuals 3. Histogram of the residuals 1: The vertical axis plots Frequency ranging from 0 to 35 in increments of 5. The horizontal axis plots Bin ranging from -1375 to 1975 in increments of 550. The values are as follow: (-1375, 3), (-825, 3), (-275, 20), (325, 35), (875, 10), (1425, 4), (1975, 5). All values approximated. 3 histograms, Histogram of the residuals 1, Histogram of the residuals 2, Histogram of the residuals 3. Histogram of the residuals 2: The vertical axis plots Frequency ranging from 0 to 30 in increments of 5. The horizontal axis plots Bin ranging from -1375 to 1975 in increments of 550. The values are as follow: (-1375, 5), (-825, 6), (-275, 15), (325, 25), (875, 16), (1425, 10), (1975, 4). All values approximated. 3 histograms, Histogram of the residuals 1, Histogram of the residuals 2, Histogram of the residuals 3. Histogram of the residuals 3: The vertical axis plots Frequency ranging from 0 to 40 in increments of 5. The horizontal axis plots Bin ranging from -1375 to 1975 in increments of 550. The values are as follow: (-1375, 3), (-825, 4), (-275, 20), (325, 35), (875, 12.5), (1425, 4), (1975, 3). All values approximated.
multiple choice 2
Histogram of the residuals 1
Histogram of the residuals 2
Histogram of the residuals 3


c-2. Is it reasonable to conclude that the normality assumption has been met?

multiple choice 3
Yes
No


d. Plot the residuals against the fitted values from the final regression equation with the residuals on the vertical axis and the fitted values on the horizontal axis. Which plot is correct?

Residuals vs Fits 1 Residuals vs Fits 2 Residuals vs Fits 3
3 scatter plots, 3 scatter plots, Residual versus Fits 1, Residual versus Fits 2, Residual versus Fits 3. Residual versus Fits 1 is titled Residuals. The vertical axis ranges from -4000 to 6000 in increments of 1000. The horizontal axis ranges from 0 to 9000 in increments of 1000. The data is scattered forming vertical lines at values 2000, 3000, 4200, 4900, 5500, 7800, 8200 along the horizontal axis. All values approximated. 3 scatter plots, 3 scatter plots, Residual versus Fits 1, Residual versus Fits 2, Residual versus Fits 3. Residual versus Fits 1 is titled Residuals. The vertical axis ranges from -4000 to 6000 in increments of 1000. The horizontal axis ranges from 0 to 9000 in increments of 1000. The data is scattered forming vertical lines at values 2000, 3000, 3600, 4200, 4900, 5500, 6000, 7800 along the horizontal axis. All values approximated. 3 scatter plots, 3 scatter plots, Residual versus Fits 1, Residual versus Fits 2, Residual versus Fits 3.Residual versus Fits 1 is titled Residuals. The vertical axis ranges from -3000 to 6000 in increments of 2000. The horizontal axis ranges from 0 to 10000 in increments of 1000. The data is scattered forming vertical lines at values 1500, 3000, 3500, 4200, 5000, 5500, 6100, 8000, 8500 along the horizontal axis. All values approximated.

multiple choice 4
Residuals vs Fits 1
Residuals vs Fits 2
Residuals vs Fits 3