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Re: st: Cox Regression


From   Marcello Pagano <pagano@hsph.harvard.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Cox Regression
Date   Fri, 19 Aug 2005 13:19:10 -0400

I would not think so. You are basing your decision of non-significance on a test whose
validity is based on an assumption. If the assumption is not valid, then neither is the test.
Think of a simple analogy with linear models. Suppose the relation between y and x is a
V-shaped one. The coefficient of x in a linear model may well test out to zero. That would
not mean that the relationship is linear.

m.p.

Timothy.Mak@iop.kcl.ac.uk wrote:


Hi when performing a Cox regression with or without a time dependent covariate, is a non-significant result in a -stphtest- generally enough evidence for the assumption of proportional hazard?
If I have multiple covariates, but I'm only interested in one, is it enough to check only the proportional hazard assumption of the variable I'm interested in? ie using the stphtest, detail, rather than stphtest?
Lastly, is it better to use stphtest log, or one of the other option rather than stphtest if hazard increases over time and most of my participants 'died' early during the observation period?
Thanks a lot for any answer.
Tim
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