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Re: st: RE: Flat or discontinuous region encountered! Help


From   "Prathiba Natesan" <prathibachaj@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: Flat or discontinuous region encountered! Help
Date   Wed, 23 Aug 2006 10:33:57 -0500

Thank you for the suggestions Nick.
    Could you please tell me how I can change my data in such a case?
Is there a way I can look for anamolies/problems? I am running a 2-PL
MLIRT model on 2 datasets, a simulated dataset and a real data (with a
sample size of abt 19,000). Both of them seem to give me the same
problems.
   Also, on #2, even if I let the program run for abt a day or 2, the
program produces about 100-200 iterations of the estimates which look
identical. Sometimes the estimates are identical upto the 3rd or 4th
decimal place. Do you think I should still wait longer for it to
converge?
 On a similar note, when the iterations fail to converge, what can be
done? What does it say abt the data?
I am currently working on my dissertation and these questions are
driving me crazy. I would appreciate any suggestions you might have.
Thanks
Prathiba
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