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Re: st: "testing" a cluster analysis
On 7 Feabh 2007, at 14:45, Adam Seth Litwin wrote:
Hi, Ronán. Your point is well-taken, and conventional hypothesis
test might not be the best tool. I have already analyzed the data
more formally with OLS, but one of my advisors suggested I see how
the observations cluster with respect to these seven binary
indicators.
If they cluster well, then the clusters will make sense. Don't forget
that clustering is an exploratory technique—it doesn't have a
dependent variable. Try to characterise the people in your clusters
and see does it make scientific sense. If the clusters are useful,
you can come up with short descriptive labels for the type of person
they contain. If not, I wonder if the process tells you anything.
Remember that cluster structures need not be simple. A cluster may be
made up of component clusters. It's worth exploring solutions with
smaller numbers of clusters to see if this happens. I'm working on a
similar problem (though clustering variables, not observations) where
there are clear clusters-within-clusters which make scientific sense.
And above all, harass your supervisor. These people can make airy,
partly-thought out suggestions that cause their students endless work!
=========
Ronán Conroy
Royal College of Surgeons in Ireland
[email protected]
+353 (0) 1 402 2431
+353 (0) 87 799 97 95
http://www.flickr.com/photos/ronanconroy
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