Introductory Econometrics 4th Edition by Jeffrey Wooldridge

تمرين 10

Use the data in MINWAGE.DTA for sector 232 to answer the following questions.
(i) Confirm that lwage232t and lemp232t are best characterized as processes. Use the augmented DF test with one lag of gwage232 and gemp232, respectively, and a linear time trend. Is there any doubt that these series should be assumed to have unit roots (ii) Regress lemp232t on lwage232t and test for cointegration, both with and without a time trend, allowing for two lags in the augmented Engle-Granger test. What do you conclude
(iii) Now regress lemp232t on log of the real wage rate, lrwage232t = lwage232t -lcpit, and a time trend. Do you find cointegration Are they "closer" to being cointegrated when you use real wages than nominal wages
(iv) What are some factors that might be missing from the cointegrating regression in part (iii)