Hello
Can you help me to explain the difference between OLS (robust or (clusters) and PPML ( Poisson Psedo- Maximum Like hood)?
I saw in some theses which including zero trade bilateral, the authors applied PPML and they said the results of the PPML are similar in sign with standard OLS, just the magnitude of coefficient estimates varies .
And for PPLM
( Poisson Psedo- Maximum Like hood), how can I do it in stata?