[R] Statistical MAYDAY request. (fwd)
Adaikalavan Ramasamy
ramasamy at stats.ox.ac.uk
Fri Aug 9 13:10:38 CEST 2002
I have been asked to forward this. Please reply directly or include the
people who have been CC-ed in this e-mail. Thank you.
> forwarded message from "Timothy Waters"
<timothy.waters at plant-sciences.oxford.ac.uk> -----
>
> Consider the following problem. You have a dataset with approx 190
> datapoints. Each datapoint has between 7 and 16 dimensions known: most
have
> 7, a few have 16, many have 14. The ones that have seven are divided into
> two categories, such that the vast bulk fall into a category with
dimensions
> 1,2,3,4,5,6,7 known, and the others have dimensions 8,9,10,11,12,13,14
> known.
>
> So, a fairly difficult dataset, but anyway.
>
> Now, on to the analysis. You wish to look for the presence of any form of
> multivariate structuring to the data, specifically, discrete clusters
> identified by combinations of one or more variables. Clearly you have a
> couple of options. You can just get it to produce a dendrogram (strictly
a
> phenogram in biological terms), or you can ask it to cluster the data into
> some number n of sets, where 1 =< n =< 10 (for present purposes) . You
can
> then look at each possible solution (i.e. each value of n) and examine
what
> discriminant function analysis tells you about the ease of separation of
the
> clusters you have identified.
>
> BUT, can you give a program a dataset (i.e., this dataset) and say "Find
n,
> where n is the number of clusters that the data is structured into, such
> that the statistical differences between clusters are maximally
> significant."
>
> Thanks for any help,
>
> Tim.
>
>
>
>
> -----End of forwarded message from "Timothy Waters"
<timothy.waters at plant-sciences.oxford.ac.uk> -----
>
>
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