Monge–Kantorovich depth, quantiles, ranks and signs

We propose new concepts of statistical depth, multivariate quantiles, vector quantiles and ranks, ranks and signs, based on canonical transportation maps between a distribution of interest on Rd and a reference distribution on the d-dimensional unit ball. The new depth concept, called Monge- Kantoro...

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Bibliographic Details
Main Authors: Galichon, Alfred, Hallin, Marc, Henry, Marc, Chernozhukov, Victor V
Other Authors: Massachusetts Institute of Technology. Department of Economics
Format: Article
Published: Institute of Mathematical Statistics 2018
Online Access:http://hdl.handle.net/1721.1/113890
https://orcid.org/0000-0002-3250-6714
Description
Summary:We propose new concepts of statistical depth, multivariate quantiles, vector quantiles and ranks, ranks and signs, based on canonical transportation maps between a distribution of interest on Rd and a reference distribution on the d-dimensional unit ball. The new depth concept, called Monge- Kantorovich depth, specializes to halfspace depth for d = 1 and in the case of spherical distributions, but for more general distributions, differs from the latter in the ability for its contours to account for non-convex features of the distribution of interest. We propose empirical counterparts to the population versions of those Monge-Kantorovich depth contours, quantiles, ranks, signs and vector quantiles and ranks, and show their consistency by establishing a uniform convergence property for empirical (forward and reverse) transport maps, which is the main theoretical result of this paper.