[R] R-equivalent Stata command: poisson or quasipoisson?
Wil M Contreras Arbaje
wil.contreras at gmail.com
Sun Sep 12 03:27:06 CEST 2010
Hello R-help,
According to a research article that covers the topic I'm analyzing,
in Stata, a Poisson pseudo-maximum-likelihood (PPML) estimation can be
obtained with the command
poisson depvar_ij ln(indepvar1_ij) ln(indepvar2_ij) ...
ln(indepvarN_ij), robust
I looked up Stata help for the command, to understand syntax and such:
www.stata.com/help.cgi?poisson
Which simply says that the command fits a Poisson regression of depvar
on indepvars. However, in my google-searching, I noticed that pseudo-
maximum-likelihood estimation is sometimes called 'quasi-maximum,' and
that R has a "quasipoisson" family that seems to allow for
overdispersion. So, am I missing something, or should I specify
"quasipoisson" when implementing this estimation?
Thanks a lot!
Cheers,
Wil
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