Hi Terry, Greg, and Marc,
Thanks for your advice about this. I think I have a pretty good starting point
now for the analysis.
Appreciate your help.
Paul
--- On Wed, 7/18/12, Terry Therneau wrote:
From: Terry Therneau
Subject: Re: [R] Power analysis for Cox regression with a time
Marc gave the referencer for Schoenfeld's article. It's actually quite
simple.
Sample size for a Cox model has two parts:
1. Easy part: how many deaths to I need
d = (za + zb)^2 / [var(x) * coef^2]
za = cutoff for your alpah, usually 1.96 (.05 two-sided)
zb = cutoff for pow
o the actual analysis itself, I'll start out
>> using the steps you've listed and see where that takes me.
>>
>> Paul
>>
>> --- On *Fri, 7/13/12, Greg Snow <538...@gmail.com>* wrote:
>>
>>
>> From: Greg Snow <538...@gmail.com&g
where that takes me.
>
> Paul
>
> --- On *Fri, 7/13/12, Greg Snow <538...@gmail.com>* wrote:
>
>
> From: Greg Snow <538...@gmail.com>
> Subject: Re: [R] Power analysis for Cox regression with a time-varying
> covariate
> To: "Paul Miller"
> Cc:
he actual analysis itself, I'll start out using the steps
you've listed and see where that takes me.
Paul
--- On Fri, 7/13/12, Greg Snow <538...@gmail.com> wrote:
From: Greg Snow <538...@gmail.com>
Subject: Re: [R] Power analysis for Cox regression with a time-varying covari
For something like this the best (and possibly only reasonable) option
is to use simulation. I have posted on the general steps for using
simulation for power studies in this list and elsewhere before, but
probably never with coxph.
The general steps still hold, but the complicated part here will
Hello All,
Does anyone know where I can find information about how to do a power analysis
for Cox regression with a time-varying covariate using R or some other readily
available software? I've done some searching online but haven't found anything.
Thanks,
Paul
_
7 matches
Mail list logo
