On Feb 23, 2012, at 11:12 AM, R-girl wrote:
Hei,
I have a one simple question which does not seem to be that simple
as I
cannot find any solution/answer:
Is it possible to compare multiple survival curves in R with
survdiff-function when there is interaction term involved in predictor
variables (and this interaction is significant)?
I've never had a problem with survival failing to construct an
interaction term.
Example:
survdiff(Surv(death,status)~treatment*gapsize)
R is making "problems" with it ie.e. it does not want to perform the
test.
Is 'gapsize' a numeric vector rather than a factor?
And all the examples I have found so far, may involve multiple
predictor
variables but in additive format (e.g. treatment+gapsize).
If survdiff is not the way to go, are there any other solutions in
order to
compare statistically the curves i.e. if they differ significantly
from each
other?
Without a better description of the data layout (say using hte str()
function) and the code you have used so far, the words "the curves",
the indefinite pronoun "they" and the phrase "each other" will remain
far too nebulous for further comment.
I would really appreciate if someone can answer!
Only if "someone" can provide the information requested in the Posting
Guide.
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org 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.
