Refer to the data given in Problem 16.12 on page 681 that represent the number of stores open for Bed Bath & Beyond from 1993 through 2010 (stored in Bed & Bath).
a. Fit a third-order autoregressive model to the number of stores and test for the significance of the third-order autoregressive parameter. (Use α = 0.05.)
b. If necessary, fit a second-order autoregressive model to the number of stores and test for the significance of the second-order autoregressive parameter. (Use α = 0.05.)
c. If necessary, fit a first-order autoregressive model to the number of stores and test for the significance of the first-order autoregressive parameter. (Use α = 0.05.)
d. If appropriate, forecast the number of stores open in 2011 and 2012.