Re: st: cluster analysis: differences between clusters

[Brendan Halpin <brendan.halpin@ul.ie>]

On Fri, Mar 07 2014, Andrea Jaberg wrote:

> I performed optimal matching for all sequences in the dataset against
> all others using -sqom- and the option -full-. Afterwards I grouped
> them using cluster analysis. Now I'd like to test whether the clusters
> are reliably different. My first thought was using ANOVA. However,
> this seems not possible since I compared all sequences against each
> other which results in a distance matrix.
> What do you suggest in order to test whether the differences between
> clusters are significant?

See Studer et al "Discrepancy Analysis of State Sequences", Sociological
Methods Research August 2011 vol. 40 no. 3 471-510

This proposes a method that uses average distance to the centre of the
pairwise distance matrix, compared with the distance to the centre of
the partitions, to create an analogue of R-squared. It also does a
pseudo-F test, with bootstrapped significance.

It naturally fits with what you are trying to do. 


There is a reference implementation in R, written by Studer, but I have
implemented it in Stata.

I will submit this to SSC, but for the moment you can download it from
http://teaching.sociology.ul.ie/bhalpin/discrepancy.zip


Regards,

Brendan
-- 
Brendan Halpin, Head of Department, Sociology, University of Limerick, Ireland
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