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RE: st: which -cmp- option to use for poisson model with count data?
From
"David Roodman ([email protected])" <[email protected]>
To
"[email protected]" <[email protected]>
Subject
RE: st: which -cmp- option to use for poisson model with count data?
Date
Mon, 30 Apr 2012 02:55:21 +0000
Laura, I'm afraid cmp is probably not appropriate. Unless the counts are high, count data can't be realistically modeled as the outcome of a single underlying process consisting of a linear functional plus a normally distributed error.
The truncated regression model is intended for the same kinds of outcomes as Stata's truncreg command--one's with a continuous but truncated outcome.
--David
------------------
From "Laura R." <[email protected]>
To [email protected]
Subject st: which -cmp- option to use for poisson model with count data?
Date Fri, 27 Apr 2012 20:16:46 +0200
Dear Stata users
Can -cmp- be used with count data, which would normally be estimated
using -poisson- in Stata? For example, the number of experts, ranging
from 0 to 5 in the data (but theoretically limited to >0) .
As this variable would be truncated (at 0, right truncated), I suppose
I should use the option -indicator($cmp_trunc)- when using -cmp-?
For example
*---------------------------- Stata example begin---------------------
cmp (experts=x1 x2 x3, trunc(0 .)), indicators($cmp_trunc)
*------------------------- Stata example end------------------------
would this be correct?
Thank you very much for your consideration.
Laura
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