The owner of the Original Italian Pizza restaurant chain would like to predict the sales of his specialty, deep-dish pizza. He has gathered data on the monthly sales of deep-dish pizzas at his restaurants and observations on other potentially relevant variables for each of his 15 outlets in central Indiana. These data are provided in the file P10_04.xlsx.
a. Estimate a multiple regression model between the quantities sold (Y) and the explanatory variables in columns C–E.
b. Is there evidence of any violations of the key assumptions of regression analysis?
c. Which of the variables in this equation have regression coefficients that are statistically different from zero at the 5% significance level?
d. Given your findings in part c, which variables, if any, would you choose to remove from the equation estimated in part a? Why?