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Re: st: ztnb model

From   Richard Williams <>
Subject   Re: st: ztnb model
Date   Thu, 27 Oct 2011 13:19:50 -0500

At 11:54 AM 10/27/2011, sara balestri wrote:
Dear Stata users,

I'm running a ztnb model on a sample of count data which, by
construction, excludes the possibility of zero counts. Overdispersion
detected in the data.
I have few questions:
1) does exist a nbvargr equivalent command to be applied for nb and
ztnb comparison?
2) my count data do not include zero counts and observations start
with a minum value of 25 for the dependent variable (by definition of
the event analysed) . I'm wondering if a ztnb is the most appropriate
model and/or if it is possible to fix the truncation at that value.
Any suggestion?

If you have Stata 12, "ztnb has been superseded by tnbreg. tnbreg allows the specification of any nonnegative integer as the left truncation point; thus it does what ztnb can do and more." Whether it is appropriate, in your case, to use a value other than 0, I don't know.

Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME:   (574)289-5227
EMAIL:  Richard.A.Williams.5@ND.Edu

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