Multivariate outlier explanations using Shapley values and Mahalanobis distances

Fuente: arXiv
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Main Authors: Mayrhofer, Marcus, Filzmoser, Peter
Format: Preprint
Published: 2022
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author Mayrhofer, Marcus
Filzmoser, Peter
author_facet Mayrhofer, Marcus
Filzmoser, Peter
contents For the purpose of explaining multivariate outlyingness, it is shown that the squared Mahalanobis distance of an observation can be decomposed into outlyingness contributions originating from single variables. The decomposition is obtained using the Shapley value, a well-known concept from game theory that became popular in the context of Explainable AI. In addition to outlier explanation, this concept also relates to the recent formulation of cellwise outlyingness, where Shapley values can be employed to obtain variable contributions for outlying observations with respect to their "expected" position given the multivariate data structure. In combination with squared Mahalanobis distances, Shapley values can be calculated at a low numerical cost, making them even more attractive for outlier interpretation. Simulations and real-world data examples demonstrate the usefulness of these concepts.
format Preprint
id arxiv_https___arxiv_org_abs_2210_10063
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Multivariate outlier explanations using Shapley values and Mahalanobis distances
Mayrhofer, Marcus
Filzmoser, Peter
Methodology
Machine Learning
For the purpose of explaining multivariate outlyingness, it is shown that the squared Mahalanobis distance of an observation can be decomposed into outlyingness contributions originating from single variables. The decomposition is obtained using the Shapley value, a well-known concept from game theory that became popular in the context of Explainable AI. In addition to outlier explanation, this concept also relates to the recent formulation of cellwise outlyingness, where Shapley values can be employed to obtain variable contributions for outlying observations with respect to their "expected" position given the multivariate data structure. In combination with squared Mahalanobis distances, Shapley values can be calculated at a low numerical cost, making them even more attractive for outlier interpretation. Simulations and real-world data examples demonstrate the usefulness of these concepts.
title Multivariate outlier explanations using Shapley values and Mahalanobis distances
topic Methodology
Machine Learning
url https://arxiv.org/abs/2210.10063