Re: st: RE: convergence problems with zinb

[Richard Williams <Richard.A.Williams.5@ND.edu>]

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
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