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Re: st: RE: convergence problems with zinb

From   Richard Williams <>
To, <>
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.

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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