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Re: st: Large standard error, Cox PH


From   Steve Samuels <sjsamuels@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Large standard error, Cox PH
Date   Fri, 27 Jul 2012 16:30:14 -0400

To answer your questions, we'd need more detail.  Describe the study and the problem variable in particular.
As the FAQ request, "Say exactly what you typed and exactly what Stata typed (or did) in response". 

Steve
sjsamuels@gmail.com




On Jul 27, 2012, at 2:20 PM, Lee Savage wrote:

I have estimated a Cox PH model using a small sample (n=19, 347 months at risk). For one of my covariates I have found a large hazard ratio (77.01) with a correspondingly large standard error (56.61). I have seen this before but every time the covariate was insignificant, in the current model the covariate is significant (p=.001). I have tested the covariates for collinearity and everything looks fine. I think the probable cause is the small sample size.


So my question is: is this a problem for my model overall model? My inclination is to report the model as it is and just state that the significant effect for the covariate in question should be treated with extreme caution, perhaps even ignored.

I'd appreciate any advice on this.

Thanks.

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