Re: [R] Problem with coxme

From: Terry Therneau <therneau_at_mayo.edu>
Date: Thu 06 Jul 2006 - 01:11:23 EST

Date: Wed, 5 Jul 2006 09:09:14 -0500 (CDT) From: Terry Therneau <therneau@mayo.edu> Subject: RE: Problem with coxme
To: jhz22@medschl.cam.ac.uk
Cc: R-help@stat.mat.ethz.ch, liulei@virginia.edu, spencer.graves@pdf.com Content-MD5: BXKVsHtW/1I9mIUqrXBU0g==

  The original question involved a strange error message from coxme when trying to fit a random slopes model:

     coxme(Surv(time, status) ~ rx+x2, data=rats2, random=~ (1+x2)|litter)
     
 Synopsis
   	a. coxme does not yet support random slopes models
  	b. it should recognize the request and print a sensible error, instead
 it just dies further down in the routine after it has gotton thoroughly  confused.

        c. the actual error message is interesting, as an example of just how  odd the error message from a confused routine can be; but has no other  use.  

   Thanks to Jing Zhao who forwarded the message on to me, as I prefer Splus (blasphemy!) and don't monitor the r-help list, and also to Spencer Graves and others who tried to further identify the bug.

		Terry Therneau
		Mayo Clinic
		(author of coxme)

PS
  Random slopes are on my "to do" list, and in fact most of the infrastructure for them is already built into the underlying C code. Unfortunately it's been on the list for 3 years now and may stay there until a data set crosses my own desk that requires it (or there is sufficient clamor from without). In my defense, I was first sidetracked by trying to understand and support pdMat structures, something I've since abandoned all hope of. They are great examples of object-oriented programming: elegant, short, code resuse, and incomprehensible (see www.netfunny.com/rhf/jokes/98/May/stroustrup.html).


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