Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: constraints


From   "Kobes, Deborah" <[email protected]>
To   "'[email protected]'" <[email protected]>
Subject   st: constraints
Date   Thu, 3 Oct 2002 10:28:03 -0400

I would like to use the constraints:

constraint define 1 [eq1]pnsdif =
[eq2]pnselig98_hat*[eq1]earndif/[eq2]earn98_hat;
constraint define 2 [eq1]matchdif =
[eq2]pnsmatches98_hat*[eq1]earndif/[eq2]earn98_hat

for a maximum likelihood estimator.  

When I try to do this, I get the error:

Constraints invalid:
not possible with test
r(131);

Is there any way I can set up constraints that define one coefficient in
terms of multiple other coefficients?  It works when I try to define one in
terms of only one other.

I am doing this because the ml model has two equations, each with a
different error term.  I'd like to constrain the coefficients for each part
to be equal to each other, but this has to take into consideration those
error terms.  

Thanks!
Deborah.
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index