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st: RE: Constraining Weibull Parameter p


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Constraining Weibull Parameter p
Date   Thu, 5 Dec 2002 19:48:31 -0000

Marita Jacob
> 
> How do I impose the restriction that the shape parameter p 
> of the weibull 
> distribution is less than 1 (i.e. monotonic decreasing 
> hazardfunction) ?
> 
> constraint define 1 [equation_name]coeff_name ??? < 1
> weibull t, dead(dead) hazard constraint(1)
> 

As I understand it, -constraint- only accepts constraints 
definable as equalities. 

Perhaps there is some algebraic 
re-expression of the model which 
would satisfy this inequality indirectly. 

On the other hand: If this 
assumption is realistic, you should 
not need a constraint. If this 
assumption is not realistic, what 
justifies this desire for force? 

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

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