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Re: st: xtfrontier

From   Federico Belotti <>
Subject   Re: st: xtfrontier
Date   Mon, 15 Jul 2013 10:48:51 +0200

It seems like your compounded error term is normal. In this case there is no evidence of inefficiency (i.e all firms are technically efficient). Alternatives are: 1) change model specification; 2) try a different SF model (see -ssc describe sfpanel-).

On Jul 13, 2013, at 6:35 PM, wrote:

> Dear Statalist,
> I recently used xtfrontier for my paper and I got some problems. I would like to estimate the technical efficiency of rice farms in some provinces between 1993-2012 using panel data. I have output as a dependent variable and each labor, fertilizer, land, seed and capital as independent variables. What makes me worry is that, for each province I have the same value of the technical efficiency for all the years and all the values are between 0.99-1.0 which is hard to believe.
> I used the following commands
> xtset   province   year
> panel   variable:   province (strongly balanced)
> time   variable:   year, 1993 to 2012
> delta:    1 unit
> xtfrontier  lny  lnx1  lnx2  lnx3  lnx4  lnx5,  tvd
> predict efficiency, te
> Any suggestion please.
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Federico Belotti, PhD
Research Fellow
Centre for Economics and International Studies
University of Rome Tor Vergata
tel/fax: +39 06 7259 5627

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