The Excel file Autos.xlsx provides quarterly U.S. auto sales in thousands of cars, GNP in billions of dollars, and the corresponding quarterly unemployment rate (Unemp) and quarterly interest rate (Int).In addition, 3 quarterly dummy variables are also included.

a)Run a multiple (linear) regression using the following functional form:

Salest = f(GNPt-1, Unempt-1, Intt-1, Q1, Q2, Q3)

(3 Points)

b)Does your regression model exhibit autocorrelation, non-normality of errors, or heteroscedasticity? (12 Points)