st: Frontier,stata 8 & stata 9

["Gauri Khanna" <gwkhanna@hotmail.com>]

Dear Statalist,

I am running the following frontier regression and insert covariates in the 
one sided error term U that captures inefficiency effects.

I thus run the following

frontier logoutput logcorarea  loglabour logmanure logfertiliserval logtrac 
logox logirrigation cropdum, uhet(experience age corarea, noconstant).

1. In stata SE 8.1 I confront an error with the noconstant option. It gives 
me an error- noconstant invalid. This is a syntax problem and I have looked 
at the stata 8 manuals and as far I understand this is the correct way. Does 
anyone know better?

2. I am also running into convergence problems with my frontier iterations. 
I decided to assign a lower tolerance level  of ltolerance(1e-4) which works 
in stata SE8.1 but refuses to converge when I use stata 9 in the office.  I 
tried 1e-7 for stata 9 but it did not work either in stata 9. Does anyone 
have a solution to the convergence problem in stata 9?

Thank you in advance.

Gauri

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