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st: RE: Weibull syntax in Stata 8


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Weibull syntax in Stata 8
Date   Mon, 24 Feb 2003 20:00:14 -0000

Sarah Hamilton
> 
> In Stata 8, there is a new command called nlcom where you can 
> define your parameters for a given distribution.  I have the 
> following code for defining the Weibull distribution and I 
> haven't been able to decipher from help files or online how to 
> interpret it.  Does anyone know what the code following each 
> parameter (theta and beta) means in Stata 8?  I would like to 
> know how it relates back to the pdf of the Weibull 
> distribution.  Thanks for any help. 
> 
> nlcom (theta:exp([ln_p]_b[_cons])) (beta:exp(-_b[_cons]))
> 

Bobby Gutierrez's recent posting applies. 

theta and beta are just parameter names supplied, 
more or less conventional. The rest 
are just expressions in Stata syntax 
defining those in terms of stuff already 
calculated. 

_b[_cons] is always Stata jargon for the 
intercept of an equation. 

exp() is the exponential function. 

[ln_p] in front specifies the equation 
being used. 


Nick 
n.j.cox@durham.ac.uk 
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