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RE: st: c-statistic in Cox models


From   Ashwin Ananthakrishnan <ashwinna@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   RE: st: c-statistic in Cox models
Date   Tue, 10 Oct 2006 07:16:11 -0700 (PDT)

Thanks for the suggestion.

I installed the somersd package, but am not sure how
to interpret the results or what represents the
c-statistic. 

I input the dependent variable and the independent
variables, but it doesn't ask me for a specific time
I'm looking at (for example failure at 12 months or at
24 months). It outputs coefficients for each of the
variables I input, but doesn't give me a c-statistic
or overall fit. 

Am I not using it correctly?

I'm also not able to use the 'estat concordance'
command suggested by another user because it doesn't
seem to run on Stata 8.0 which is the version I have
at my workplace (which I cannot upgrade to 9.0 due to
some policy reasons in the workroom).

Thanks,
Ashwin

 


--- "Newson, Roger B" <r.newson@imperial.ac.uk> wrote:

> The -somersd- package, downloadable from SSC using
> the -ssc- command,,
> also calculates general Harrell c-indices, and also
> Somers' D and
> Kendall's tau-a. There is an example in the manual
> -somersd.pdf-, which
> is distributed with the package as an ancillary
> file.
> 
> I hope this helps.
> 
> Roger
> 
> 
> Roger Newson
> Lecturer in Medical Statistics
> Respiratory Epidemiology and Public Health Group
> National Heart and Lung Institute
> Imperial College London
> Royal Brompton campus
> Room 33, Emmanuel Kaye Building
> 1B Manresa Road
> London SW3 6LR
> UNITED KINGDOM
> Tel: +44 (0)20 7352 8121 ext 3381
> Fax: +44 (0)20 7351 8322
> Email: r.newson@imperial.ac.uk 
> www.imperial.ac.uk/nhli/r.newson/
> 
> Opinions expressed are those of the author, not of
> the institution.
> 
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On
> Behalf Of Jacki Buros
> Sent: 08 October 2006 02:29
> To: statalist@hsphsun2.harvard.edu
> Subject: Re: st: c-statistic in Cox models
> 
> Hi Ashwin,
> 
> Try the stcox postestimation command -estat
> concordance-, which
> calculates Harrell's C. This may be what you want
> for the survival
> analysis, so long as you do not have time-varying
> covariate effects.
> 
> I don't know whether there is a similar command for
> svy regress.
> 
> Jacki
> 
> On 10/7/06, Ashwin Ananthakrishnan
> <ashwinna@yahoo.com> wrote:
> > Hi,
> >
> > Is there a command in stata where I can calculate
> the
> > c-statistic for predictive models in Cox
> regression
> > survival analysis?
> >
> > I tried the stcstat program that I found online
> but
> > that doesn't seem to be working. Are there other
> > commands?
> >
> > Is there a similar c-statistic command for use in
> > survey analysis also? (following a .svylogit or a
> > .svyregress command) ?
> >
> > Thanks.
> >
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