[R] Contrast in GEE

WWei@mdanderson.org
Fri, 18 Feb 2005 23:08:00 -0000

Hi, List,

I am using the package 'gee' downloaded from CRAN several days ago. I
tried to
do a 2 degree freedom contrast but couldn't get any result. It must be so
obvious but I just couldn't get it. Any hint would be greatly appreciated.
Here
is a sample code:

set.seed(123)
mydf <-
data.frame(trm=rep(letters[1:3],each=9),animal=rep(1:9,each=3),res=sample(c(rep(0,12),rep(1,15))))
mygee <-
gee(res~trm,id=animal,data=mydf,family=binomial,corstr='unstructured',
contrasts=list(trm=matrix(c(1,0,-1,1,-1,0),nrow=3)))

I couldn't find the result of contrasts except this:

> mygee$contrasts
$trm
  [,1] [,2]
a    1    1
b    0   -1
c   -1    0

where can I extract the p-value of this contrast testing though?

Thank you in advance,

Auston


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