Hi,
You can use `model.matrix' to create the apropriate design matrix for factor
variables.
set.seed(10)
ftime <- rexp(200)
fstatus <- sample(0:2,200,replace=TRUE)
gg <- factor(sample(1:3,200,replace=TRUE),1:3, c('a','b','c'))
cov <- matrix(runif(600),nrow=200)
dimnames(cov)[[2]] <- c('x1','x2','x3')
cov2 = model.matrix( ~ cov + gg)
print(z <- crr(ftime,fstatus,cov2[, -1])) # you shouldn't have intercept in
the FG model
Hope this helps,
Ravi.
____________________________________________________________________
Ravi Varadhan, Ph.D.
Assistant Professor,
Division of Geriatric Medicine and Gerontology
School of Medicine
Johns Hopkins University
Ph. (410) 502-2619
email: rvarad...@jhmi.edu
----- Original Message -----
From: kende jan <kende...@yahoo.fr>
Date: Sunday, August 2, 2009 6:01 am
Subject: [R] Competing Risks Regression with qualitative predictor with more
than 2 categories
To: r-help@r-project.org
> Hello,
> I have a question regarding competing risk regression using cmprsk
> package (function crr()). I am using R2.9.1. How can I do to assess
> the effect of qualitative predictor (gg) with more than two categories
> (a,b,c) categorie c is the reference category. See above results, gg
[[elided Yahoo spam]]
> Thank you for your help
> Jan
>
> > # simulated data to test
> > set.seed(10)
> > ftime <- rexp(200)
> > fstatus <- sample(0:2,200,replace=TRUE)
> > gg <- factor(sample(1:3,200,replace=TRUE),1:3,c('a','b','c'))
> > cov <- matrix(runif(600),nrow=200)
> > dimnames(cov)[[2]] <- c('x1','x2','x3')
> > cov2=cbind(cov,gg)
> > print(z <- crr(ftime,fstatus,cov2))
>
> convergence: TRUE
> coefficients:
> x1 x2 x3 gg
> 0.2624 0.6515 -0.8745 -0.1144
> standard errors:
> [1] 0.3839 0.3964 0.4559 0.1452
> two-sided p-values:
> x1 x2 x3 gg
> 0.490 0.100 0.055 0.430
> > summary(z)
> Competing Risks Regression
>
> Call:
> crr(ftime = ftime, fstatus = fstatus, cov1 = cov2)
>
> coef exp(coef) se(coef) z p-value
> x1 0.262 1.300 0.384 0.683 0.490
> x2 0.652 1.918 0.396 1.643 0.100
> x3 -0.874 0.417 0.456 -1.918 0.055
> gg -0.114 0.892 0.145 -0.788 0.430
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
>
> PLEASE do read the posting guide
> and provide commented, minimal, self-contained, reproducible code.
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