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Re: st: GMM with inequality and equality constraints
From
Stas Kolenikov <[email protected]>
To
[email protected]
Subject
Re: st: GMM with inequality and equality constraints
Date
Thu, 15 Mar 2012 10:52:32 -0400
The first one looks like the regular GMM equation to me. The second
one is pretty much impossible to implement directly. You can introduce
a Lagrange multiplier in front of it:
E lambda[ gamma y_i + delta z_i ] = 0
You would probably run into identification problems and/or problems
with the standard errors: if the constraint is active, then gamma and
delta are not identified; if it is not, then lambda is identically
zero, and would have to have a missing standard error.
On Thu, Mar 15, 2012 at 10:40 AM, Marder, Andrew <[email protected]> wrote:
> Dear statalisters,
>
> The generalized method of moments estimation in Stata is great! It was wonderful how easy it is to estimate a nonlinear GMM model. I am trying to replicate part of a paper that estimates a GMM model subject to equality and inequality constraints that look like:
>
> E[ alpha w_i + beta x_i ] = 0
> E[ gamma y_i + delta z_i ] >= 0
>
> How hard would it be to modify Stata's gmm function to accommodate constraints like these?
>
> Thanks, Andrew
>
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--
Stas Kolenikov, also found at http://stas.kolenikov.name
Small print: I use this email account for mailing lists only.
*
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