Re: [R] C-index and Cox model

2010-04-09 Thread Terry Therneau
Bessy wrote: > Dear all R users, > > I am building a Cox PH model on a small dataset. I am wondering how to > measure the predictive power of my cox model? Normally the ROC curve or Gini > value are used in logistic regression model. Is there any similar > measurement suitable for Cox model? > >

Re: [R] C-index and Cox model

2010-04-08 Thread Frank E Harrell Jr
Bessy wrote: Dear all R users, I am building a Cox PH model on a small dataset. I am wondering how to measure the predictive power of my cox model? Normally the ROC curve or Gini value are used in logistic regression model. Is there any similar measurement suitable for Cox model? Also if I use

Re: [R] c-index validation from Design library

2009-07-17 Thread Frank E Harrell Jr
Juliet Hannah wrote: Hi Group, I have a question about obtaining the bias-corrected c-index using validate from the Design library. As an example, consider the example from help page: library(Design) ?validate.lrm n <- 1000 age<- rnorm(n, 50, 10) blood.pressure <- rnorm(n, 120, 15

Re: [R] C-index for models fitted using start, stop in Surv?

2009-02-26 Thread Terry Therneau
One of my colleagues has written a technical report on how to do this, but I have not yet implemented it in the survival package. Terry Therneau http://mayoresearch.mayo.edu/mayo/research/biostat/techreports.cfm #80 Concordance for Survival Time Data: Fixed and Time-Depende

Re: [R] C-index for models fitted using start, stop in Surv?

2009-02-25 Thread Eleni Rapsomaniki
223 740273 Strangeways Research Laboratory Department of Public Health and Primary Care University of Cambridge -Original Message- From: Frank E Harrell Jr [mailto:f.harr...@vanderbilt.edu] Sent: 25 February 2009 17:50 To: Eleni Rapsomaniki Cc: r-help@r-project.org Subject: Re: [R] C-index

Re: [R] C-index for models fitted using start, stop in Surv?

2009-02-25 Thread Frank E Harrell Jr
Eleni Rapsomaniki wrote: Dear R-users, One can use the rcorr.cens function in Design to compute the C index when only the stop time is indicated (I think implicitely start=0 in that case). When the start and stop times are used in a Surv object, e.g. library(Design) S=with(heart, Surv(start,s

Re: [R] C-index

2008-02-05 Thread Frank E Harrell Jr
bereket weldeslassie wrote: > Hi > > I am using Cox regression to identify at risk groups. How can I get the > C-index in R? > > Thanks, > > Bereket library(Hmisc) ?rcorr.cens # assumes no overfitting Also: library(Design) ?validate # penalizes for overfitting Frank > <'[EMAIL PROTECTED]'>

Re: [R] C-index

2008-02-05 Thread bereket weldeslassie
Hi > > I am using Cox PH regression using the coxph function to identify at risk > groups. How can I get the C-index (area under ROC curve) statistic in R? > > Thanks, > > Bereket > [[alternative HTML version deleted]] __ R-help@r-project.org