[R-sig-eco] repeated measures with multivariate data

[Rafael Maia]

Interesting that you ask; I was currently thinking about the same thing. Once a reviewer required us to do a Doubly Repeated Measures ANOVA "Doubly because the multiple variables and the repeated measures parts are both multivariate dimensions." At the time, I did not find how to do it in R, and was wondering just this week if something similar could be done using a mixed model...


Abraços,
Rafael Maia
---
"A little learning is a dangerous thing; drink deep, or taste not the Pierian spring." (A. Pope)
Graduate Student - Integrated Bioscience
University of Akron
http://gozips.uakron.edu/~shawkey/

On Jul 23, 2010, at 7:08 PM, Peter Solymos wrote:

> Kay,
> 
> using strata (restricting permutations within time points, and not
> within locations) in adonis makes some sense, given that permutation
> tests assume independence. But that does not solve the problem of
> dependence, but it is a good starter. If you have a before-after
> control-treatment design, you might want to use the absolute
> difference between observations and do the adonis on the matrix of
> differences (the dissimilarity then will represent distance in terms
> of absolute deviation between time points). However, this won't show
> the sign of the change, which might be of interest. If you have larger
> number of repeated observations, the MARSS package is just appeared on
> CRAN to fit multivariate autoregressive state-space models using a
> Kalman-filter approach.
> 
> Cheers,
> 
> Peter
> 
> Péter Sólymos
> Alberta Biodiversity Monitoring Institute
> and Boreal Avian Modelling project
> Department of Biological Sciences
> CW 405, Biological Sciences Bldg
> University of Alberta
> Edmonton, Alberta, T6G 2E9, Canada
> Phone: 780.492.8534
> Fax: 780.492.7635
> email <- paste("solymos", "ualberta.ca", sep = "@")
> http://www.abmi.ca
> http://sites.google.com/site/psolymos
> 
> 
> 
> On Fri, Jul 23, 2010 at 1:02 PM, Kay Cichini <Kay.Cichini at uibk.ac.at> wrote:
>> 
>> dear list,
>> 
>> i searched though the archives and the question of repeated measure analysis
>> with species data was often brought up but, as far as i found, never clearly
>> worked out.
>> 
>> if i have, say two time points at wich i sampled replicated plots and thus
>> had replicated paired mutivariate obervations, how to deal with them
>> properly.
>> 
>> if i used adonis, to restrict permutations on the pairs of plots (as this
>> would be done in an univariate permutation test for paired observations)
>> does not make sense to me but i'm also dubious about neglecting the
>> dependence of the pairing.
>> 
>> any ideas would be highly appreciated,
>> kay
>> 
>> -----
>> ------------------------
>> Kay Cichini
>> Postgraduate student
>> Institute of Botany
>> Univ. of Innsbruck
>> ------------------------
>> 
>> --
>> View this message in context: http://r-sig-ecology.471788.n2.nabble.com/repeated-measures-with-multivariate-data-tp5330819p5330819.html
>> Sent from the r-sig-ecology mailing list archive at Nabble.com.
>> 
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