Message-ID: <200901121858.n0CIw0g06846@hsrnfs-101.mayo.edu>
Date: 2009-01-12T18:58:00Z
From: Terry Therneau
Subject: rpart with interval censored data crashes R
Thank you for the input on rpart -- I just saw the message today.
1. You are right, it should not crash. Why it crashes rpart is simply that I
(the author) never ever tried using interval censored data in the call. Real
users try the most amazing things....
I'll fix it in my local version, but putting in a "no no no" message. My
local version and the R version, maintained by Brian, have drifted quite far
apart however.
2. Rpart deals with right censored data using the same trick as Cox models, by
thinking of it as observation of a Poisson process; number of events seen over a
given time window. The fact that the number is always 0 or 1 doesn't hinder the
mathematical trick, which is based in counting process theory.
BUT - the trick only works for right censored data.
Using the mid points of your intervals is the only approach that comes readily
to mind.
Terry Therneau