Re: [R] Treatment-response analysis along time

From: Peter Dalgaard <p.dalgaard_at_biostat.ku.dk>
Date: Wed 10 Aug 2005 - 19:15:58 EST

"Felix Royo" <z319112@hotmail.com> writes:

> Dear R people,
> I wonder if you could give me a hand with some of my data. I have a very
> typical analysis in biology, however it is difficult for me to find the
> right way to analyse. I had a group of animals, I gave them a treatment, and
> I measure a variable along time -one´s per day- along 5 days,for
> example(fake data):
> Animals Time1 Time2 Time3 Time4
> 1 1 5 3 1
> 2 2 7 4 1
> 3 5 5 3 1
> 4 1 3 7 2
> 5 2 7 7 1
> Please, notice that all the animals get the same treatment, and there are no
> control -animals which has no received any treatment.
> Normally I handle this kind of data with SPSS and Repeated Measurement
> analysis. That tell me if there is a change along the time, but no
> information about when the treatment start to be effective, when the effect
> has pass. Besides, i would like to be able to handle this data with R.
> I have been looking at Crawley's S-plus book, and I cannot find similar
> example as I have, not either in the Dalgaard´s introduction to R, because
> he uses an example where different animals are measured as each time -using
> time as a factor in a one way anova (I am hope I am right).
> Thanks for your help and time.
> Best regards
> Felix

ISwR is hardly an extensive treatise on repeated measurements, but two-way ANOVA *is* in there (Section 6.3 and 10.6 for the replicated case). Notice that you need a different data layout for that, basically the result of a reshape(...direction="long").

Also, the capabilities of the newer mlm methods are relevant for this kind of data (see ?anova.mlm, and the examples).

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)                  FAX: (+45) 35327907

______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Received on Wed Aug 10 19:20:32 2005

This archive was generated by hypermail 2.1.8 : Sun 23 Oct 2005 - 15:12:02 EST