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Re: st: predict with xtfrontier


From   nicola.baldini2@unibo.it
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: predict with xtfrontier
Date   Thu, 02 Aug 2007 18:32:31 +0200

The answer is: E(inverse te_scores)
However, please note that the output in the interval [1; infinity) is common for cost function models (see e.g. the package Frontier, which uses such interval for cost functions, and the interval [0, 1) for production functions). Also, some authors (e.g. in Research Policy 31, 109124) inverted the program's output in order to obtain efficiencies in the interval [1; infinity) 

Nicola

At 02.33 31/07/2007 -0400, "Dascha Orlova" wrote:
>Hi,
>
>I'm estimating a cost function with xtfrontier. After the estimation I predict the efficiency scores using predict te_scores,te.
>
>The predicted scores are in the intervall (1;eternity) and hard to interprete though. 
>
>The subject has been discussed here already and I've read:
>http://www.stata.com/statalist/archive/2005-06/msg00578.html
>and
>http://www.stata.com/statalist/archive/2007-06/msg00926.html.
>
>However these threads don't really solve my problem: which way do I compute the MEAN efficiency to make it comparable to other studies? Invertation affects the distribution of the scores, so the results vary between:
>E(inverse te_scores)
>and 
>1/(E(originally predicted te_scores))
>
>I hope, I managed to explain my problem :-) 

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