1. What order of differencing is chosen? Does this result agree with your previous conclusions?  2. What model was chosen by AIC? 3. Which goodness-of-fit criterion is being used here?  4. Change the...

1. What order of differencing is chosen? Does this result agree with your previous conclusions?

 2. What model was chosen by AIC?

3. Which goodness-of-fit criterion is being used here?

 4. Change the criterion to BIC. Does the best-fitting model then change?

 5. Carefully express the fitted model chosen by the BIC criterion in mathematical notation.

Finally, refit the best-fitting model with the following code, and check for any residual autocorrelation. You will need to replace the three question marks by the appropriate numerical values for the best-fitting model.