Determine whether a two-period lag for Direct Mail would model Sales better than the one-period lag model. 1. First, create a variable Direct Mail Lagged 2. 2. Then, fit a regression model for Sales and Direct Mail Lagged 2. 3. Compare the p-values, RSquare, RMSE, the predicted value, and the prediction interval. 4. Which, of the two, is the better model? 5. Why would it be unwise to consider higher-order lags, say, a 10-week lag for Direct Mail