Use the data set BARIUM.

This shows imports of Barium Chloride into the United States from China [chnimp] for the period Feb 1977 to December 1987 (131 observations)

1. Carry out a regression of chnimp on time period t using only the first 119 observations (up to the end of 1986). Hence estimate the Linear trend.
2. Carry out regression of chnimp_t on chnimp_t-1 using only the first 119 observations (up to the end of 1986). Hence estimate an AR(1) model.
3. Use the estimated equations from parts (1) and (2) to forecast the imports for 1987 and compare these with the actual figures.
4. Comment critically on the value of the models created for forecasting.