This is the code I have used "xtabond2 ROA l.ROA CR LR2TA MR OR ZIR CE OWN SIZE HHIA NPLTL l.GDPG, gmm (ROA CR LR MR OR ZIR, lag (2 2)) iv(CE OWN SIZE HHIA NPLTL IDIV l.GDPG) small twostep"
Is it necessary that I add robustness? What should I add to make the results better?