Consider the actual sales shown in Table P-2 along with one-step-ahead forecasts produced by Winters' method and by a regression model.

a. Construct the combined forecasts of sales produced by taking a simple average of the forecasts produced by Winters' method and the regression model.
b. Construct the combined forecasts of sales produced by taking a weighted aver-age of the Winters' forecasts and the regression forecasts with weights w1 = .8 and w2 = 1 €“ w1 = .2.
c. Using the actual sales, determine the MAPEs for the Winters' forecasts and the regression forecasts.
d. Repeat part c using the combined forecasts from parts a and b. Based on the MAPE measure, which set of forecasts do you prefer?

TABLE P2 ActualWinters' Regression Month Sales Forecasts Forecasts 15,502 4,586 5,263 2 6,535 5,944 6,008 3 7390 6,706 6,832 4 4,388 4,530 4886 5 452 5010 4918 6 5,679 6,574 5.630 7 8,578 8,46 7963 8 7.088 6.415 5,942 9 4,839 4457 5.156 10 4,050 4,638 3819