[Forum SIS] Seminario 13 Giugno 2012 - DAIS - Ca' Foscari, Venezia

[Claudio Agostinelli]

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AVVISO DI SEMINARIO
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Mercoledi' 13 GIUGNO 2012 alle ore 15.30, nell'aula E del plesso di
Santa Marta, Dipartimento di Scienze Ambientali, Informatica e
Statistica, Universita' Ca' Foscari, Venezia

Prof. *PETER FILZMOSER*
Department of Statistics and Probability Theory
Vienna University of Technology

terra' un seminario dal titolo:

*Compositional data analysis: Challenges for environmental sciences*

Abstract:
Many practical data sets in environmental sciences are in fact
compositional data because only the ratios between the variables are
informative. Compositional data are represented in the Aitchison
geometry on the simplex, and for applying statistical methods designed
for the Euclidean geometry they need to be transformed first.
The isometric logratio transformation has the best geometrical
properties, and it avoids the singularity problem introduced by the
centered logratio transformation. Since real environmental data also
often contain outlying observations, robust statistical procedures need
to be employed. We show for different multivariate methods how
robustness can be managed for compositional data, provide algorithms
for the computation, and apply the methods on real data sets from
geochemistry.
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