Introduction to Econometrics 3rd Edition by James Stock, Mark Watson

تمرين 11

Suppose that you have the same data as in Exercise 13.7 (panel data with two periods, n observations), but ignore the W regressor. Consider the alternative regression model
Y it , = ß o + ß 1 X it , + ß 2 G i + ß 3 D 1 + u it ,
where Gj = 1 if the individual is in the treatment group and Gj = 0 if the individual is in the control group. Show that the OLS estimator of /T is the differences-in-differences estimator in Equation (13.4).