Using the data for Problem 16.17 on page 646 concerning the number of passenger cars produced in the United States from 1999 to 2012 (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 2013?