Use the 4-8Cyl data set to calculate the regression line Price = 0 + 1(Mileage) + 3(Cadillac)

Question:

Use the 4-8Cyl data set to calculate the regression line Price = β0 + β1(Mileage) + β3(Cadillac) + β4(SAAB). You will need to create indicator variables for Make before calculating the regression line.
a. Create a scatterplot with Mileage as the explanatory variable and Price as the response. Overlay a second graph with Mileage as the explanatory variable and y n as the response. The predicted values (the y values) form two separate lines. Do the parallel lines (no interaction model) look appropriate?
b. Conduct one extra sum of squares test to determine if interaction terms (MileCadillac and MileSAAB) are important to the model (i. e., test the hypothesis H0: β5 = β6 = 0 versus Ha: at least one of the coefficients is not 0, where b5 and b6 are the coefficients for the two interaction terms). Create a scatterplot with the full regression model to explain the results of the hypothesis test.