Si avvisa che in data 21-11-2018, alle ore 14:30 precise, presso l'Aula
Seminari "F. Saleri" VI piano, Dipartimento di Matematica, Politecnico di
Milano, si svolgerà il seguente seminario:
Relatore
Eva Fiserova, Palacky University Olomouc, Czech Republic
Titolo
Working with compositional data in coordinates
Abstract
Compositional data are multivariate observations carrying only relative
information, popularly expressed in percentages, proportions, mg/kg, etc.
Because of features inherent to compositional data, such as scale invariance
and the relative scale, the statistical analysis of raw compositional data
often leads to spurious results. Natural principles of compositional data
are followed by the Aitchison geometry on a simplex, the sample space of
compositional data (Aitchison, 1986; Pawlowsky-Glahn et al., 2015). However,
because most standard statistical methods rely on the Euclidean geometry in
real space, compositional data need to be converted to this space prior to
statistical processing. In the lecture, we will present the log ratio
methodology for dealing with compositional data and several types of their
coordinate representations, such as orthonormal log-ratio coordinates, pivot
coordinates, weighted pivot coordinates (Hron et al., 2017), or symmetric
balances (Kynvclova et al., 2017). Their usage will be demonstrated on
examples.
Tutti gli interessati sono invitati a partecipare.
Cordiali saluti,
Alessandra Menafoglio
--
Alessandra Menafoglio
MOX - Dept. of Mathematics
Politecnico di Milano
Piazza Leonardo da Vinci, 32,
20133, Milan Italy
Phone: +39 02 2399 4642
Email: <mailto:alessandra.menafoglio@polimi.it>
alessandra.menafoglio(a)polimi.it