hi,

I agree, mixture modelling can handle your specific data.
for mixure modelling, try MCLUST
http://www.stat.washington.edu/fraley/software.html/

There are also some good papers and reports on the site.

regards,
jacco
-------------------------------------------
J.C. Noordam
Agrotechnological Research Institute (ATO)
Department Production & Control Systems
P.O.Box 17,6700 AA Wageningen, the Netherlands
http://www.ato.wageningen-ur.nl
email : [log in to unmask]
tel: +31.317.475139
fax: +31.317.475347


> -----Original Message-----
> From: shannon [mailto:[log in to unmask]]
> Sent: woensdag 23 oktober 2002 13:32
> To: [log in to unmask]
> Subject: Re: Clustering question
>
>
> Hi
>
> I would think this could occur only in a special case where a mixture
> model approach can be used. The data would need to be from
> three different
> multivariate normal distributions, each with the same
> covariance matrix.
> If you do a web search on 'mixture models' you will come up with the
> information you need.
>
> I don't know of and can't imagine any type of hierarchical or scaling
> approach that could be used.
>
>
> Bill
> ---
>
> William D. Shannon, Ph.D.
>
> Assistant Professor of Biostatistics in Medicine
> Division of General Medical Sciences and Biostatistics
>
> Washington University School of Medicine
> Campus Box 8005, 660 S. Euclid
> St. Louis, MO   63110
>
> Phone: 314-454-8356
> Fax: 314-454-5113
> e-mail: [log in to unmask]
> web page: http://ilya.wustl.edu/~shannon
>
>
> On Wed, 23 Oct 2002, Marinucci, Max (MB Ergo) wrote:
>
> > Dear all
> >
> >
> > I would like to know if there is some clustering provedure
> which does the
> > following.Given a data set with n observations on k variables with
> > correlations matrix R (k x k) I would like to obtain 3 cluster of
> > approximatively equal size n1=n2=n3 that satisfy the
> following condition.
> >
> >
> > The correlations matrix of each of the three subgroups
> should be as close as
> > possible each other and with respect to the pooled
> correlation matrix, That
> > is R1=R2=R3=R
> >
> >
> > Do you have any suggestions or ideas on how to proceed to
> obtain such
> > partitions?
> >
> >
> > Thanx a lot
> >
> >
> > Massimiliano Marinucci
> >
> >
> > Phd candidate
> >
> >
> > Universidad Complutense Madrid
> >
> >
> >
> >
> >
> >
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