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Re: st: What should I do if stata can not show the result of nbreg

 From "Justina Fischer" To statalist@hsphsun2.harvard.edu Subject Re: st: What should I do if stata can not show the result of nbreg Date Sun, 08 Jan 2012 16:32:10 +0100

```Hi Yes Sun,

usually (from my experience), nbreg needs about 7 iterations to converge.

One reason for non-convergence could be
a high collinearity among variables.

So try with a more parsimonous model and find out which independent variable causes the problem.

Justina
-------- Original-Nachricht --------
> Datum: Sun, 8 Jan 2012 21:25:56 +0800
> Von: Ye SUN <sunye74stata@gmail.com>
> An: statalist@hsphsun2.harvard.edu
> Betreff: Re: st: What should I do if stata can not show the result of nbreg

> Thanks for reminding.
> I use stata 11. My dependent variable is the number of boards that a
> director serves in.(Nboards) My test independent variable is the
> gender of the director, dummy variable (FD).
> So I want to run the following regression:  nbreg  Nboards  FD  (other
> control variables)
>
> I input the above command in stata, but it runs for hours and keeps
> showing
>
> Iteration 50:  log likelihood = -58271.444  (backed up)
> numerical derivatives are approximate
> flat or discontinuous region encountered
> Iteration 51:  log likelihood = -58271.444  (backed up)
> numerical derivatives are approximate
> flat or discontinuous region encountered
> Iteration 52:  log likelihood = -58271.444  (backed up)
> numerical derivatives are approximate
> flat or discontinuous region encountered
> Iteration 53:  log likelihood = -58271.444  (backed up)
>
> I want to know how to solve this problem if it still can not show the
> final results.
>
> I also want to know what is the difference between the command -nbreg-
> and -nbinreg-, please? It seems both of them are used for negative
> binomial regression.
>
> Thanks a lot
>
> SUN Ye
>
>
> On Sun, Jan 8, 2012 at 4:36 PM, Muhammad Anees <anees@aneconomist.com>
> wrote:
> > A little picture of what you really did with -nbreg- will help us
> > understand your problem and also indicate what version of Stata is
> > used.
> >
> > On Sun, Jan 8, 2012 at 1:24 PM, Ye SUN <sunye74stata@gmail.com> wrote:
> >> Dear all
> >> My dependent variable is count number: the number of boards that a
> >> director serves in (this kind of data seems not fit to poisson)
> >>
> >>  I first try poisson regression and get the results and then I  try
> >> -estat gof-  to test whether there is overdispersion problem, it is
> >> insignificant indicating no overdispersion problem I think.
> >> I also try -zip- and get similar results, and vuong test indicates
> >> there is no excess zero problems I think.
> >>
> >> I also want to try negative binomial regression,(  nbreg  and zinb ),
> >> but stata run for quite a long time and still run without showing any
> >> results. What does that mean? Dose it mean that nbreg is inappropriate
> >> here?
> >>
> >> I want to ask, if -estat gof- after -poisson- shows the insignificant
> >> results, can I say this poisson model is OK and do not need to provide
> >> negative binomial regression results?
> >>
> >> Thanks for your help!
> >>
> >> SUN Ye
> >> *
> >> *   For searches and help try:
> >> *   http://www.stata.com/help.cgi?search
> >> *   http://www.stata.com/support/statalist/faq
> >> *   http://www.ats.ucla.edu/stat/stata/
> >
> >
> >
> > --
> >
> > Best
> > ---------------------------
> > Assistant Professor/Programme Coordinator
> > COMSATS Institute of Information Technology
> > Attock 43600, Pakistan
> > http://www.aneconomist.com
> >
> > *
> > *   For searches and help try:
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> > *   http://www.stata.com/support/statalist/faq
> > *   http://www.ats.ucla.edu/stat/stata/
>
> *
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--
Justina AV Fischer, PhD
COFIT Fellow
University of Bern

homepage: http://www.justinaavfischer.de/
e-mail: javfischer@gmx.de. justina.fischer@wti.org
papers: http://ideas.repec.org/e/pfi55.html

*
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*   http://www.stata.com/help.cgi?search
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```