Colloquium MATH

Davy Paindaveine (ULB): An excursion through statistical depth

Europe/Brussels
CYCL 01 (Marc de Hemptinne)

CYCL 01

Marc de Hemptinne

chemin du Cyclotron 2
Description
Statistical depth aims at measuring centrality of any given location in the d-dimensional Euclidean space with respect to probability distributions over this space. For empirical distributions, depth provides (i) a deepest point, that usually can be seen as a multivariate median, and (ii) a center-outward ordering of the observations. Depth may therefore be considered as a concept of multivariate ranks. In this lecture, we will introduce the main concepts of depth, including Tukey's halfspace depth and Liu's simplicial depth. We will present some well-known properties and discuss Serfling's axiomatic approach. We will then briefly describe some inferential applications of depth. If time permits, the strong relation between depth and multivariate quantiles will be examined, and depth will be extended from (vector-valued) location parameters to (matrix-valued) dispersion ones.
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