what is the difference in ltfp to gmm what is the lag in systems dtfp why is it necessary to add lag to lag gmm what is the lag of the difference and the system gmm in a stata why is the lag in xtabond gmm significant what is the statistical significance of the difference and system gmm? what is the lag in gmm what is the difference and system gmm in stata how can i use xtabond2 for difference what is the lag of system and difference if tfp is statistically significant in gmm then what is the difference? lag in xtabond is lags in a regression statistically significant what is the difference between xtabond and system gmm ltfp is statistically significant whereas tfp level is not. what is the lag of xtabond difference system and system gmm test xtabond dtfp lag(ltfp) iv what is the statistical significance of dtfp ltfp what is the lag in a gmm