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st: Re: RE: Re: Initial values not feasible and -ufrom()- option.


From   Weihua Guan <wguan@stata.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Re: RE: Re: Initial values not feasible and -ufrom()- option.
Date   Thu, 10 Jul 2003 11:24:59 -0500

--"Wu, Xun" <WuX@wharton.upenn.edu> wrote,

> Thanks for Scott's information and David's method, I solve the initial value
> problem in Frontier with the -from()- option . 
> 
> http://www.stata.com/statalist/archive/2003-05/msg00650.html
> 
> However, when I was trying to fit a truncated-normal model, I still have a
> problem with option -ufrom()-.
> 
> I follow David Drucker's method to feed my own initial values:
> 1. Run OLS
> 2. matrix b0 = e(b), ln(e(rmse)^2), .1
> 3. I add option to the frontier command: distribution(tnormal) ufrom(b0,
> copy)
> 
> However, I always got a message "ufrom() must specify a matrix".
> 
> Is there anything different with -ufrom()- option?

The -ufrom()- option is a little different from the regular -from()-.  Unlike
-from()-, -ufrom()- only takes a matrix.  The syntax is like:

. frontier ..., ufrom(matname) ...

Xun should not specify ", copy" in his command. 


Weihua Guan <wguan@stata.com> 
Stata Corp.

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