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st: RE: Flat or discontinuous region encountered! Help


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Flat or discontinuous region encountered! Help
Date   Wed, 23 Aug 2006 15:47:31 +0100

On #1, the likelihood depends on the model 
and the data. Therefore, you must
change one or both of those to make
any difference here. 

On #2, the estimates may look identical
to the precision printed, but -ml- 
may still be climbing, or trying to climb. 

Nick 
n.j.cox@durham.ac.uk 

Prathiba Natesan

>       I am evaluating a polytomous IRT model in Stata using GLLAMM and
> frequently encounter the following errors. Can someone help?
> 1. Often I get a msg that says, flat or discontinuous region
> encountered. What can I do to fix this?
> 2. Sometimes, the log likelihood produces identical estimates as the
> previos estimate and still continues to run. Does this mean that it
> has gotten into an unconditional looping or does it mean that there is
> some problem with the data?

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