st: no convergence

[demariaf@unical.it]

Dear Alls,

I have a big database in which the number of rows is equal to 2188934  
and the number of  column is approximate to 190 (including fixed  
effects), and I have 4 years.

I have estimated my model using both pooled and cross-section data by  
a Poisson.

While the pooled estimation converges, I have a problem when I run the  
cross-section data: The poisson is not concave. I did several proofs  
using different maximize options but the results do not change.  what  
can I do?

Thanks


Federica




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