Bookmark and Share

Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down on April 23, and its replacement, is already up and running.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

st: unequal constraints

From   Sirak <>
Subject   st: unequal constraints
Date   Wed, 14 Jul 2010 11:40:16 +0200

Hello all stata list memebers,
In estimating an econometric cost function and associated share
equations (using Stata 10.1), I have tried to estimate an equation
with constraints that three of the parameters sum to one. While these
constraints held when estimating the equations for the cost function
with the -sureg- command, the estimates of the parameters (input
shares) took on values less than zero and greater than one, which are
not possible in practice.

I tried to define inequality constraints like this.

eg. constraint 1 _b[y3x1] = 1 - _b[y2:x1] - _b[y1:x1],
    sureg (y1 x1 x2 x3)    ///
      (y2 x1 x2)              ///
      (y3 x1 x2), constraints (1)         ///
the constraint 1 _b[y3x1] = 1 - _b[y2:x1] - _b[y1:x1], this is to get
the sum of input shares is equal to one.
What about if I want to make constraints for the coefficients to be
greater than one. In other ways how do I make inequality constraints
in regeression???
I appreciate your help.

*   For searches and help try:

© Copyright 1996–2015 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   Site index