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Re: st: constrained linear least-squares problems without using ML
From
Steven Samuels <[email protected]>
To
[email protected]
Subject
Re: st: constrained linear least-squares problems without using ML
Date
Wed, 29 Jun 2011 17:38:12 -0400
Ali,
you need to use -nl-. See the example at:
http://www.stata.com/statalist/archive/2011-06/msg00110.html
Steve
[email protected]
On Jun 28, 2011, at 9:51 PM, ali hashemi wrote:
Dear list members,
I would like to estimate an OLS model (y=b1*x1+b2*x2) with proportionate
coefficients which means considering the following constraints:
b1>0
b2>0
b1+b2=1
I tried to estimate this using ML (for more details: findit inequality
constraints)
It works for some cases. Unfortunately, for many other cases it keeps giving
this message: "flat or discontinuous region encountered"
I'm told that ML is not the best option to estimate constrained linear
least-squares models. lsqlin in MATLAB and quadratic programming in R are
solutions that I have found in other packages. However, I'm not aware of any
alternative method in Stata? Does anyone have any idea how constrained
linear least-squares models can be estimated without using ML?
Your help is greatly appreciated.
Best,
Ali
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