The file S11_44.xlsx contains data on pork sales. Price is in dollars per hundred pounds sold, quantity sold is in billions of pounds, per capita income is in dollars, U.S. population is in millions, and GDP is in billions of dollars.
a. Use these data to develop a regression equation that can be used to predict the quantity of pork sold during future periods. Is autocorrelation of residuals a problem?
b. Suppose that during each of the next two quarters, price is $45, U.S. population is 240, GDP is 2620, and per capita income is $10,000. Predict the quantity of pork sold during each of the next two quarters.
c. Use Winters’ method to develop a forecast of pork sales during the next two quarters. Does it appear to provide better (or different) predictions than the multiple regression in part a?