Using the data file Product Sales, estimate autoregressive models of orders 1-4 for product sales. Using the

Question:

Using the data file Product Sales, estimate autoregressive models of orders 1-4 for product sales. Using the procedure of Section 16.4 for testing the hypothesis that the autoregressive order is p - 1 against the alternative that the order is p, with a significance level of 10%, choose one of these models.
Compute forecasts for the next 3 years from the chosen model.