Hi list, I want to use the p-value from the survdiff function (package survival) to reuse within a function in a Kaplan-Meier plot. The p-value is somehow not a component of the value list ?! Thanks in advance -- A. Goralczyk G?ttingen, Ger.
If sdf <- survdiff(...) is your survdiff object, the p-value can be computed as follows: p.val <- 1 - pchisq(sdf$chisq, length(sdf$n) - 1) and then use it in your K-M plot. -Christos Christos Hatzis, Ph.D. Nuvera Biosciences, Inc. 400 West Cummings Park Suite 5350 Woburn, MA 01801 Tel: 781-938-3830 www.nuverabio.com> -----Original Message----- > From: r-help-bounces at stat.math.ethz.ch > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Armin Goralczyk > Sent: Thursday, April 26, 2007 3:03 PM > To: R-help at stat.math.ethz.ch > Subject: [R] Extract p-value from survdiff function > > Hi list, > I want to use the p-value from the survdiff function (package > survival) to reuse within a function in a Kaplan-Meier plot. > The p-value is somehow not a component of the value list ?! > > Thanks in advance > -- > A. Goralczyk > G?ttingen, Ger. > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >
You have the Chi^2 statistic and you know that it is on 1 degree of freedom with a 2-sample test. So sdf <- survdiff(...) pchisq(sdf$chisq, df=1, lower=FALSE) might help in quite a common case. Generally you'll have to look at the printing function and make a modified copy to save the p-value: getAnywhere(print.survdiff) hth Petr Armin Goralczyk napsal(a):> Hi list,I want to use the p-value from the survdiff function (packagesurvival) to reuse within a function in a Kaplan-Meier plot. Thep-value is somehow not a component of the value list ?! > Thanks in advance-- A. GoralczykG?ttingen, Ger. > ______________________________________________R-help at stat.math.ethz.ch mailing listhttps://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code. >-- Petr Klasterecky Dept. of Probability and Statistics Charles University in Prague Czech Republic