U.S. unemployment 2017, part 2.

Using the data from Exercise 49 develop and compare the following models:

a) Fit a regression model with just Year as the predictor.

b) Add a lag1 component to the model of part

a. How does it change the coefficient of Year?

c) Add lag2 and lag3 components to the model. How do the coefficients change?

d) Can you account for these changes? (Hint: Find the correlations among the Rate and lagged versions of the Rate.)