1) The case suggests that promotional activities (consumer packs and dealer allowances, among others) affect overall demand, and may be felt over an extended period. As a result, the effects of promotional activities are felt during the month of the promotion and up to two months after the promotion. Create columns showing one-month and two-month lags of consumer packs and dealer allowances.
2) Create a trend variable indicating the month of the time series (month 1 for January 1984 thru month 48 for December 1987).

                                                                                                                                                               Order Now