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st: checking and correcting proportional hazard assumption with categorical and time dependent variables
From
Dorean Nabukalu <[email protected]>
To
[email protected]
Subject
st: checking and correcting proportional hazard assumption with categorical and time dependent variables
Date
Wed, 23 Mar 2011 07:23:05 -0700 (PDT)
Dear all,
I have one or two questions.
I understand that one can use the stphtest to test for proportionality in a
cox model and if violated can add an interaction term with time using the tvc
and texp command for continous variables.
My question is
how do you approach that similar problem with categorical variables (having more
than 2 levels)?
If one of the variables (categorical) changes with time, how do I handle it in
the model?
Stratifying does not help much because I have more than one variable varying
with time and also would like to estimate the effect of the stratifying
variable.
I will be grateful for any assistance rendered
Dorean
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