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. The Bureau of Labor Statistics tracks national unemployment rates on a monthly and annual basis. Use statistical software to analyze annual unemployment rates from 1948 to 2007.18

(a) Make a time series plot of the unemployment rate time series.

(b) Describe any important features of the time series. Is there evidence of a trend in the series over the long run? How would you best describe the time behavior of the series?

(c) Make a lagged time series plot of the unemployment rate time series. Does this plot suggest that an AR(1) model is appropriate for this time series? Why or why not?