Q1) Owner of Original Italian Pizza restaurant chain would like to forecast sales of his speciality, deep-dish pizza. He has collected data on monthly sales of deep-dish pizzas at his restaurants and observations on other potentially applicable variables for each of his 15 outlets in central Pennsylvania. 

a) Evaluate the multiple regression model between quantity sold (Y) and following explanatory variables: average price of deep-dish pizzas, monthly advertising expenditures, and disposable income per household in areas surrounding outlets.

b) Which of the variables in this model have regression coefficients which are statistically different from 0 at the 5% significance level?

c) Based on your findings in part c, which variables, if any, would you select to remove from model estimated in part a? Describe your decision.