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Re: st: RE: convergence problems with zinb


From   Richard Williams <Richard.A.Williams.5@ND.edu>
To   statalist@hsphsun2.harvard.edu, <statalist@hsphsun2.harvard.edu>
Subject   Re: st: RE: convergence problems with zinb
Date   Wed, 13 Aug 2008 20:25:50 -0500

At 07:03 PM 8/13/2008, Kieran McCaul wrote:
Hi Margaret,

You might like to look at the various maximize options that you can
tinker with.

Type - help maximize

There are four different algorithms used by ml and Stata follows a rule
for stepping though these when fitting a model.  There is an option
called - difficult - which tells the ml program to use a different
stepping rule.  You could try this.
The difficult option is definitely worth a try. I've occasionally seen it make a dramatic difference.

Beyond that, I think it is usually a good idea to start with a simpler model and then build it up. There might be one or two variables that are creating havoc. Or, maybe you are just spreading the data too thin.


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Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
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EMAIL: Richard.A.Williams.5@ND.Edu
WWW: http://www.nd.edu/~rwilliam

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