Introductory Econometrics 4th Edition by Jeffrey Wooldridge

تمرين 6

Estimate equation (10.2) using all the data in PHILLIPS.RAW and report the results in the usual form. How many observations do you have now
(ii) Compare the estimates from part (i) with those in equation (10.14). In particular, does adding the extra years help in obtaining an estimated tradeoff between inflation and unemployment Explain.
(iii) Now run the regression using only the years 1997 through 2003. How do these estimates differ from those in equation (10.14) Are the estimates using the most recent seven years precise enough to draw any firm conclusions Explain.
(iv) Consider a simple regression setup in which we start with n time series observations and then split them into an early time period and a later time period. In the first time period we have n1 observations and in the second period n2 observations. Draw on the previous parts of this exercise to evaluate the following statement: "Generally, we can expect the slope estimate using all n observations to be roughly equal to a weighted average of the slope estimates on the early and later subsamples, where the weights are n1/n and n2/n, respectively."