Suppose the median weekly earnings for recent college graduates in a large city by quarter for the years 2004 to 2011 are as follows:

a. Prepare a line chart of the median earnings by quarter.
b. Estimate a linear trend line for this set of data.
c. Produce a forecast for each quarter using the linear trend line you estimated in part b.
d. Calculate the error for each period.
e. Calculate the Durbin-Watson statistic and test for positive autocorrelation. Use a level of significance of 0.05.