[Marco Astori]

Sure Sebastian Kripfganz it was so simple, I got confused, thank you

[Marco Astori]

If you are estimating the model by system GMM, it is sufficient to include time dummies as instruments for the level model only, i.e. iv(i.year, eq(level)).

Of course it should be possible to use them without suboption, right?

[Sebastian Kripfganz]

I am not a fan of not specifying the eq() suboption, but you can do it.

[Marco Astori]

Thank you Sebastian Kripfganz