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RE: st: Perfect predictors of an occurrence (survival analysis)


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   RE: st: Perfect predictors of an occurrence (survival analysis)
Date   Thu, 13 Mar 2008 14:48:02 +0000 (GMT)

--- Luis Ortiz <luis.ortiz@upf.edu> wrote:
> > The problem is that some of my covariates, seemingly, do not change
> > their value during t. The type of contract does not change while
> > the individual holds a job for which s/he is over-educated.
> > 
> > In other words, the type of contract perfectly predicts my outcome
> > 
> > As you'll see next, whenever I run the model with sex and age
> > dummies, everything is OK. Yet, if I add to the model the 
> > type-of-contract dummies....

--- Maarten buis <maartenbuis@yahoo.co.uk> wrote:
> I don't know the answer, but I think I can eliminate one potential
> cause, which I hope is sorta helpful. You claim the the prolem is
> that the contract doesn't change over time. This can't be  the
> problem, because you report that the model works OK when you add sex,
> and this presumably doesn't change over time either. 

Maybe the final record of each spell already records the type of
contract for the next job. I can imagine how a process of generating
spells would result in that, and how such a structure could lead to
perfect predictions (though I am not sure).

-- Maarten

-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


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