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What is fair? Proxy discrimination vs. demographic disparities in insurance pricing

Lindholm, M., Richman, R., Tsanakas, A. ORCID: 0000-0003-4552-5532 & Wüthrich, M. V. (2024). What is fair? Proxy discrimination vs. demographic disparities in insurance pricing. Scandinavian Actuarial Journal, 2024(9), pp. 935-970. doi: 10.1080/03461238.2024.2364741

Abstract

Discrimination and fairness are major concerns in algorithmic models. This is particularly true in insurance, where protected policyholder attributes are not allowed to be used for insurance pricing. Simply disregarding protected policyholder attributes is not an appropriate solution, as this still allows for the possibility of inferring protected attributes from non-protected covariates, leading to the phenomenon of proxy discrimination. Though proxy discrimination is qualitatively different from the group fairness concepts discussed in the machine learning and actuarial literatures, group fairness criteria have been proposed to control the impact of protected attributes on the calculation of insurance prices. The purpose of this paper is to discuss the relationship between, on the one hand, direct and proxy discrimination in insurance and, on the other, the most popular group fairness axioms. We provide a technical definition of proxy discrimination and derive incompatibility results, showing that avoiding proxy discrimination does not imply satisfying group fairness and vice versa. This shows that the two concepts are materially different. Furthermore, we discuss input data pre-processing and model post-processing methods that achieve group fairness in the sense of demographic parity, using as a main tool the theory of optimal transport. As these methods induce transformations that explicitly depend on policyholders’ protected attributes, it becomes ambiguous whether they can be said to avoid direct and proxy discrimination.

Publication Type: Article
Additional Information: This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.
Publisher Keywords: Discrimination, indirect discrimination, proxy discrimination, fairness, protected attributes, discrimination-free, unawareness, group fairness, demographic parity, statistical parity, independence axiom, equalized odds, separation axiom, predictive parity, sufficiency axiom, input pre-processing, output post-processing, optimal transport, Wasserstein distance.
Subjects: H Social Sciences > HF Commerce
H Social Sciences > HG Finance
H Social Sciences > HN Social history and conditions. Social problems. Social reform
Departments: Bayes Business School
Bayes Business School > Actuarial Science & Insurance
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