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Re: st: R: compare median survival times? (flag: Stata 9.2/SE)


From   Ronan Conroy <rconroy@rcsi.ie>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: R: compare median survival times? (flag: Stata 9.2/SE)
Date   Fri, 11 Jun 2010 18:44:21 +0100

On 11 Meith 2010, at 15:48, Martin X wrote:

Thanks for your input, Carlo and Ronan. I agree with Ronan that the code below will only compare survival functions with defined median survival times. The hypothesis itself is motivated by my desire to be able to say that half of group A survived 30 months and half of group B survived 20 months, and the 10 month difference between A and B is statistically significant. I've already used cox reg to compare the survival functions (and logistic reg to compare survival at a given time endpoint). Now, I just want to be able to provide some "common language" results (i.e. months of survival for half the group).


I agree with your desire to present the results as an effect size. However, picking just one point on the function may be misleading. The hazard ratio is a useful global measure of effect, as is Harrell's c.


Ronan Conroy
=================================

rconroy@rcsi.ie
Royal College of Surgeons in Ireland
Epidemiology Department,
Beaux Lane House, Dublin 2, Ireland
+353 (0)1 402 2431
+353 (0)87 799 97 95
+353 (0)1 402 2764 (Fax - remember them?)
http://rcsi.academia.edu/RonanConroy

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