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Re: st: Inequality constraint with mata -optimize-


From   Richard Williams <richardwilliams.ndu@gmail.com>
To   statalist@hsphsun2.harvard.edu, statalist@hsphsun2.harvard.edu
Subject   Re: st: Inequality constraint with mata -optimize-
Date   Sun, 29 May 2011 19:21:30 -0500

At 06:09 PM 5/29/2011, Dorothy Bridges wrote:
Thanks, Stas.  I am using ML to estimate a disequilibrium model, in
which the likelihood function is set up as in Maddala and Nelson,
"Maximum Likelihood Methods for Models of Markets in Disequilibrium,"
Econometrica, 1974.  I simply want to constrain two of the parameters
-- variances of the error terms in the demand and supply equations --
to be greater than or equal to zero.

Often this is done by estimating the log of the parameter. See, for example, Stata's -hetprob- program.


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