Hello everyone,
i am doing my first regression analysis with STATA and i now want to control for self-selection bias.
My panel data set contains observations for firms in Ghana on real log output per worker, real log capital per worker, log unskilled workers, log skilled workers, years (1991-2002), and a dummy variable if they exported in a year.
I now want to control for the self-selection bias according to literature:
"To test whether today’s export starters were more productive than today’s non-exporters several years back when all of them did not export, select all firms that did not export between year t − 3 and t − 1, and compute the average difference in labour productivity in year t − 3 between those firms who did export in year t and those who did not. More formally, estimate the empirical model: ln LP_it−3 = a + β Export_it + c Control_it−3 + e_it." (Wagner, 2007)
I am unsure if this code produces the results i am looking for.
Thank you in advance for your support!
All the best,
Colin
i am doing my first regression analysis with STATA and i now want to control for self-selection bias.
My panel data set contains observations for firms in Ghana on real log output per worker, real log capital per worker, log unskilled workers, log skilled workers, years (1991-2002), and a dummy variable if they exported in a year.
I now want to control for the self-selection bias according to literature:
"To test whether today’s export starters were more productive than today’s non-exporters several years back when all of them did not export, select all firms that did not export between year t − 3 and t − 1, and compute the average difference in labour productivity in year t − 3 between those firms who did export in year t and those who did not. More formally, estimate the empirical model: ln LP_it−3 = a + β Export_it + c Control_it−3 + e_it." (Wagner, 2007)
Code:
gen export_control = exports egen export_num = total(exports == 1 & year >= 1991 & year <= 1993), by( firm) replace export_control = . if export_num >= 1 & year == 1991 replace export_control = . if export_num >= 1 & year == 1992 replace export_control = . if export_num >= 1 & year == 1993 drop export_num //generating lags for our controls variables gen lag_lrcapnpc = l3.lrcapnpc gen lag_lskill = l3.lskill gen lag_lunsk = l3.lunsk gen lag_lroutputpc = l3.lroutputpc gen lag_export = l1.export_control global controls = "lag_export lag_lrcapnpc lag_lskill lag_lunsk" xtreg lag_lroutputpc $controls i.year, fe
Thank you in advance for your support!
All the best,
Colin
