[Eeglablist] How many clusters to choose for a STUDY?

[Joaquin Rapela]

Dear Aleksandra,

I select the number of clusters in such a way that (ideally) each cluster has one component from every cluster. That is if my study contains 27 subjects, I select the number of subjects so that each cluster contains 27 components from 27 subjects. Of course, this is only an ideal scenario, but one that could guide you to a good number of clusters.

After you have decided on a number of clusters, and analyzed your data with these number of clusters, it is a good practice to repeat the analysis with a slightly different number of clusters, to get an idea of the robustness of your conclusions.

Cordially, Joaquin

On Mon, Mar 05, 2012 at 09:41:08PM +0000, Aleksandra Vuckovic wrote:
> Dear all,
> I’m clustering ICAs of three groups in a STUDY and was just wondering what would be the best indicator for how many clusters are just right (apart for experimentally testing different numbers). I’ve noticed that some cluster contain more than 100 components while some other 20-30 IC . Does it mean that this with 100 component is too large so I should go for larger number of clusters to separate this cluster in two, or 20-30 CI is too small number and I should reduce the total number of clusters?
> Many thanks,
> Aleksandra

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-- 
Joaquin Rapela, PhD
Swartz Center for Computational Neuroscience
University of California San Diego
9500 Gilman Drive,
San Diego, CA 92093-0559
tel: (858) 822-7536
fax: (858) 822-7556
http://sccn.ucsd.edu/~rapela
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