On Aug 16, 2011, at 6:36 AM, Jim Trabas wrote:
Dear R help gurus,
I have the following problem and I would be delighted if you could
help me.
From a large (1500) cohort of patients we have been taking some
measurements
(ECG measurements, but its not important). The measurements are
ordinal in 4
grades (Grade I-IV, grade IV being the most severe form). Every
patients has
been measured several times (usually once per year). The follow-ups
are
different for each patient (ranging from days to several years),
thus some
patients have only 1 measurement and some have several. A patient
can shift
from Grade to Grade, that is a patient can be measured now as Grade
I and
later as Grade II and then at then next measurement he can return to
Grade
I.
This should probably be followed up on the mixed models SIG list.
(Using Baron's RSiteSearch page.)
Search results with : repeated "proportional odds logistic"
http://finzi.psych.upenn.edu/R/library/repolr/html/00Index.html
http://finzi.psych.upenn.edu/R/Rhelp02/archive/99576.html
Search results with: repeated "ordered logit"
http://finzi.psych.upenn.edu/R/library/ordinal/doc/primer.pdf
That last one has citations to Agresti articles, which means it may
have useful termininogy to be used in searching the very informative
Thompson/Agresti compendium of R methods:
https://home.comcast.net/~lthompson221/Splusdiscrete2.pdf
The mixed-models SIG would seem to be a natural place to look and for
that I use the advanced search panel fpr google to construct this
search of its archives:
http://www.google.com/search?hl=en&lr=&q=repeated+logit+site%3Ahttps%3A%2F%2Fstat.ethz.ch%2Fpipermail%2Fr-sig-mixed-models
(I did trim some of the trailing bits that seemsed superfluous.)
--
David.
My data are in the following format
Patient ID, Time of Measurement, Grade
I would like to model the probability of being in each of the Grades
(I-V)
as a function of time. I guess i require a repeated measure
cumulative logit
mixed model with random slope and intercept (for each patient).
Could anyone pin point me at any information that would help me
accomplish
this in R? Packages? Books?
Information about categorical data analysis with R seems to be poor
in the
Internet.
Thank you very much on advance
JT
--
View this message in context:
http://r.789695.n4.nabble.com/Repeated-measures-cummulative-logit-mixed-model-tp3746845p3746845.html
Sent from the R help mailing list archive at Nabble.com.
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David Winsemius, MD
West Hartford, CT
______________________________________________
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