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st: Using the maximum likelihood heckman - in the presence of missing variables


From   "georg wernicke" <georg.wernicke@googlemail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Using the maximum likelihood heckman - in the presence of missing variables
Date   Wed, 8 Aug 2007 13:00:54 +0100

Hello,

I tried to use the maximum likelihood heckman and got the error term
r(504) saying that the hessian matrix has become unstable. most likely
that error term evolved since i, for some years, miss some independent
variables.

Do i have to use the heckman two step instead?

Thank you very much,

regards


georg wernicke
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