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
Treatment-response analysis along time
3 messages · Felix Royo, Dimitris Rizopoulos, Peter Dalgaard
you haven't told us what kind of variable you measure, but either way look at lmer() function in lme4 package which fits both linear and generalized linear mixed-effects models. I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/16/336899 Fax: +32/16/337015 Web: http://www.med.kuleuven.be/biostat/ http://www.student.kuleuven.be/~m0390867/dimitris.htm ----- Original Message ----- From: "Felix Royo" <z319112 at hotmail.com> To: <r-help at stat.math.ethz.ch> Sent: Wednesday, August 10, 2005 9:09 AM Subject: [R] Treatment-response analysis along time 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 ______________________________________________ R-help at 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
"Felix Royo" <z319112 at 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 ??ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907