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Re: st: xtfrontier error

From   Joseph Coveney <>
To   Statalist <>
Subject   Re: st: xtfrontier error
Date   Mon, 14 Nov 2005 18:00:03 +0900

Raiqah Kamil wrote:

I am trying to estimate the producer specific
technical efficiency  (time invariant) using a
firmlevel panel data. When I use the "xtfrontier"
command as outlined in the help, stata is returning an
no observations
I haven't worked with the panels earlier. Can anyone
suggest what is the nature of problem here? I would
appreciate any help on this.


I don't know anything about frontier models or how to use -xtfrontier-, but
that same error message appears whenever I forget to -encode- string
variables before using -anova-.

Are any of your variables string ?  (For example, categories for a
predictor.)  If so, then try -encode- (or -destring-, if appropriate) to see
if this helps.

Joseph Coveney

. use, clear

. xtfrontier lnwidgets lnworkers lnmachines, i(id) t(t) tvd nolog

[successfully fit--output deleted]

. tostring lnwidgets, replace force
lnwidgets was float now str12
lnwidgets was forced to string; some loss of information

. xtfrontier lnwidgets lnworkers lnmachines, i(id) t(t) tvd nolog
no observations

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