Using the data for Problem 16.17 on page 626 concerning the number of passenger cars produced in the United States from 1999 to 2011 (stored in Car Production).
a. Fit a third-order autoregressive model to the number of passenger cars produced in the United States and test for the significance of the third-order autoregressive parameter. (Use a = 0.05.)
b. If necessary, fit a second-order autoregressive model to the number of passenger cars produced in the United States and test for the significance of the second-order autoregressive parameter. (Use a = 0.05.)
c. If necessary, fit a first-order autoregressive model to the number of passenger cars produced in the United States and test for the significance of the first-order autoregressive parameter. (Use a - 0.05.)
d. forecast the U.S. car production for 2012.