[Forum SIS] Seminar of Prof. C. Hennig

[Claudio Agostinelli]

Apologies for cross-posting

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DIPARTIMENTO DI SCIENZE AMBIENTALI, INFORMATICA E STATISTICA
Universita' Ca' Foscari
VENEZIA
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Seminar

Prof. Christian Hennig
Department of Statistical Science
University College London

HOW TO FIND THE BEST CLUSTER ANALYSIS
METHOD (IN A SETUP WITH MIXED TYPE VARIABLES)

Friday October 28th, 2011 at 2.30pm
Aula Consiglio - Ala 2C, S. Giobbe, Venezia

Anyone interested is invited to participate

Abstract:
This presentation will treat two issues.
1. A general approach for the decision about the ``best'' cluster
analysis method will be sketched. This is based on the idea that a
subjective decision is needed about the cluster concept required in a
particular application, and that there is no such thing as an
objectively true clustering determined by the data alone. For
example, even if data can be perfectly fitted by a Gaussian mixture,
this does not necessarily mean that the mixture components correspond to
the "true" clusters, because in a given application unimodal mixtures of
more than one Gaussian may be considered as a single cluster (see Hennig
2010). On the other hand, large within-cluster dissimilarities may not
be admissible, in which case certain Gaussian components need to be
split up.
2. The general philosophy is applied to the problem of defining social
strata from data with mixed continuous, ordinal and categorical
variables. Clusterings as obtained from a mixture/latent class approach
(as for example fitted by the LatentGOLD software, Vermunt and Magidson,
2005) are compared with clusterings obtained from applying k-medoids
(Kaufman and Rousseeuw, 1990) to dissimilarities balancing the different
types of variables in a sensible user-specified way.

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Claudio Agostinelli
Department of Environmental Sciences, Informatics and Statistics
Ca' Foscari University
San Giobbe, Cannaregio 873
30121 Venezia
Tel: 041 2347446, Fax: 041 2347444
email: claudio at unive.it, www: www.dst.unive.it/~claudio
skype: claudio.agostinelli
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20 Ottobre 2011
Giornata Italiana della Statistica
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