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RE: st: xtmelogit model not converging


From   "Hardy, Dale S" <Dale.S.Hardy@uth.tmc.edu>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   RE: st: xtmelogit model not converging
Date   Wed, 3 Feb 2010 09:26:38 -0600

Maarten,

It seems that I have multicollinearity with some of the variables; so I made dummy variables for these variables and include these instead of the original variables in the model. It seems to be working thus far.


Thanks for replying back.

Dale


Dale Hardy, PhD RD CDE CHES
Research Associate
University of Texas School of Public Health
Houston, TX 77030
Phone: (713) 500-9221
Fax: (713) 500-9264
Email: dale.s.hardy@uth.tmc.edu



________________________________________
From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten buis [maartenbuis@yahoo.co.uk]
Sent: Wednesday, February 03, 2010 9:01 AM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: xtmelogit model not converging

--- On Tue, 2/2/10, Hardy, Dale S wrote:
> I am running a logistic mixed model and the performing
> gradient-based optimization iterations are not concave, so
> the model is not converging. Can you tell me what can be
> wrong? How can I fix it?

The standard advise is to simplify the model, so remove the
random coeficient for race, if that model converges you can
try a model with random coefficient for race, if that model
converges you can try to relax the covariance between the
random coefficients by adding the -covariance(unstructured)-
option.

-- Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------




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