Dear Statalists,

I am doing two-step system GMM xtabond2

the dependent variable is rgdpg

endogenous variables are rgdpg ihs_inigdppc fdxstwo

exegnouse varaibles are ihs_inf ihs_gfcf ihs_gov ihs_trd ihs_lbor

the command that I used:

xtabond2 rgdpg rgdpg_lag1 ihs_inigdppc fdxstwo ihs_inf ihs_gfcf ihs_gov ihs_trd ihs_lbor y*, gmm(rgdpg ihs_inigdppc fdxstwo , lag(2 5) collapse eq(diff)) iv(ihs_inf ihs_gfcf ihs_gov ihs_trd ihs_lbor, eq(diff)) gmm(rgdpg ihs_inigdppc fdxstwo, lag(1 .) collapse eq(level)) twostep robust

I have read Roodman (2009). However, I still confused

1- Is this command correct?
2- Can I increase the number of lags in gmm(rgdpg ihs_inigdppc fdxstwo, lag(1 .) collapse eq(level))
3- I put the time variable y* at the beginning of the command but not in gmm () eq(level) is that ok!

I will be very grateful for any help

Thank you

Badiah