R help - Sep 2010 - repeated measurements ANOVA

Dear list,

i am setting up a GLM for a repeated measurement ANOVA using the lm and 
ANOVA function. my design contains four factors with 5, 5, 2 and 2 (= 
14) levels, respectively. the data are stored in a data.frame with six 
columns, one for the data themselves and the remainings for the factors 
where strings indicate the factor levels in each row. now i would like 
to restructure this data.frame using cbind which yields a 100 x 14 
array. so far i only included two subjects in the analysis and the 100 
rows emerge because each subject contributes 50 values. for the ANOVA 
however, it seems to me that i should create a multi-dimensional array 
where each dimension accounts for one specific factor and its levels. is 
it possible to do this in R? if so, does the lm or ANOVA function 
necessitates this type of array or is there yet another way to continue?


Best

Alex

Hi Alex,

I'm slightly unclear as to why you would want to restructure your nice 
six-column data.frame (why six? One column for the data and four for the 
factors should make five, shouldn't it? I guess you have a subject ID in 
one column?) into some monstrosity which I assume you would fill with 
lots of indicator variables. R does all this for you, just do something like

library(nlme)
lme(response~factor1+factor2+factor3+factor4,random=~1|ID,data=dataset)

assuming that your data.frame is called dataset with column names 
response, factor1, ..., factor4 and ID (and that the above is the model 
you want). Take a look at the help page for lme() and the Orthodont data 
set, which is used as an example in the lme() help page. And next time, 
send along a snippet of your data.frame, that would help us help you.

HTH
Stephan


Am 07.09.2010 20:19, schrieb Walther, Alexander:
> Dear list,
>
> i am setting up a GLM for a repeated measurement ANOVA using the lm and
> ANOVA function. my design contains four factors with 5, 5, 2 and 2 (>
14) levels, respectively. the data are stored in a data.frame with six
> columns, one for the data themselves and the remainings for the factors
> where strings indicate the factor levels in each row. now i would like
> to restructure this data.frame using cbind which yields a 100 x 14
> array. so far i only included two subjects in the analysis and the 100
> rows emerge because each subject contributes 50 values. for the ANOVA
> however, it seems to me that i should create a multi-dimensional array
> where each dimension accounts for one specific factor and its levels. is
> it possible to do this in R? if so, does the lm or ANOVA function
> necessitates this type of array or is there yet another way to continue?
>
>
> Best
>
> Alex
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

You can find the layout of data for repeated measuremnt ANOVA in examples
from UCLA computing page:

http://www.ats.ucla.edu/stat/R/seminars/Repeated_Measures/repeated_measures.htm
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