I think you are looking for a multivariate measure of association, analogous to R^2 for a univariate linear model. If so, there are
extensions of eta^2 from univariate ANOVAs for each of the multivariate
test statistics, e.g.,

for Pillai (-Bartlett) trace and Hotelling-Lawley trace and a given effect tested on p response measures

eta2(Pillai) = Pillai / s
eta2(HLT) = HLT / (HLT+s)
where s = min(df_h, p)

Alternatively, you could look at the candisc package which, for an s-dimensional effect, gives a breakdown of the variance reflected in
each dimension of the latents roots of HE^{-1}


Sam Brown wrote:
Hello everybody

After doing a MANOVA on a bunch of data, I want to be able to make some comment 
on the amount of variation in the data that is explained by the factor of 
interest. I want to say this in the following way: XX% of the data is explained 
by A.

I can acheive something like what I want by doing the following:
X <- structure(c(9, 6, 9, 3, 2, 7), .Dim = as.integer(c(3, 2)))
Y <- structure(c(0, 2, 4, 0), .Dim = as.integer(c(2, 2)))
Z <- structure(c(3, 1, 2, 8, 9, 7), .Dim = as.integer(c(3, 2)))

U <- rbind(X,Y,Z)
m <- manova(U~as.factor(rep(1:3, c(3, 2, 3))))

summary(m,test="Wilks")

SS<-summary(m)$SS

(a<-mean(SS[[1]]/(SS[[1]]+SS[[2]])))

and concluding that 94% of variation is explained.

Is my desire misguided? If it is a worthy aim, is this a valid way of acheiving 
it?

Thanks a lot!

Sam

Samuel Brown

Research assistant

Bio-Protection Research Centre

PO Box 84

Lincoln University

Lincoln 7647

Canterbury

New Zealand

sam.br...@lincolnuni.ac.nz

http://www.the-praise-of-insects.blogspot.com

_________________________________________________________________

ws Live
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Professor, Psychology Dept.
York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
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