st: Gmm for panel with selection

[ncdcta00@uniroma2.it]

Dear All,
I have need to understand how I can to estimade in stata a panel  
unbalanced, with unobserved heterogenety and Where I have selection,  
with gmm.
I have my equation of wage for female that participate in labor  
market, I possible estimated this by porobit year by year and after  
calculated the lambda and put its in  a regression ols, but if I want  
to aplly gmm how you do ?
thanks a lot for your help


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