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st: Clarification on biprobit

From   "Alfredo Paloyo" <>
To   <>
Subject   st: Clarification on biprobit
Date   Sat, 26 Feb 2005 11:28:26 +0800


Let me answer some of my own questions.  I'll truncate them into
separate email for brevity.  ;)

> 2.  -mfx- is able to compute the marginal effects of the first 
> specification (with standard errors, too).  However, when I try it on 
> the constrained -biprobit-, it responds with
> "warning:  derivative missing; try rescaling variable p".  
> How could this happen?

I tried this method a few times but it didn't solve the problem.  The
crucial question for me, though, is why -mfx- fails with constraints
(setting the coefficient of one independent variable to zero) but is
successful when simply deleting the variable from the equation.


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