R help - Feb 2012 - Hotelling T2 test extension for multigroup data

Hi all,
I've got the following matrix :
?
mat <- matrix(rnorm(700), ncol=5, dimnames=list( paste("f",
c(1:140), sep="_"), c("A", "B", "C",
"D", "E")))

I can see that currently most of the multivariate Hotelling T2 tests are limited
for application on two groups/samples.

I wud appreciate if someone can provide me a suggestion how to implement the
same for multiple groups.


Thx,
- Vickie

On Feb 9, 2012, at 12:11 , Vickie S wrote:
> 
> Hi all,
> I've got the following matrix :
>  
> mat <- matrix(rnorm(700), ncol=5, dimnames=list( paste("f",
c(1:140), sep="_"), c("A", "B", "C",
"D", "E")))
> 
> I can see that currently most of the multivariate Hotelling T2 tests are
limited for application on two groups/samples.
> 
> I wud appreciate if someone can provide me a suggestion how to implement
the same for multiple groups.
> 
Please don't start up a new thread, cloning the same misconceptions as an
earlier one! It doesn't help, you will only get people misunderstanding you
in the same way...

Apparently, you have rows and columns reversed relative to the common layout in
multivariate analysis. Also, you have only one observation for each of your
"groups" (species)?

What makes you think that T^2 would work for you if you had only "A"
and "B" species? I don't think anything will work unless you have
either replication or some sort of additional assumptions on the covariance
structure of your 140-dimensional response.

-- 
Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com