Measuring Fairness Under Unawareness of Sensitive Attributes: A Quantification-Based Approach

TL;DR

This paper proposes a novel quantification-based method to measure group fairness in models without access to sensitive attributes, addressing privacy and legal constraints while maintaining robustness to distribution shifts.

Contribution

It introduces a quantification approach to assess fairness under unawareness, decoupling sensitive attribute inference from fairness measurement and outperforming previous methods.

Findings

Quantification methods effectively measure demographic parity without sensitive attributes.

The approach is robust to distribution shifts in five experimental protocols.

Outperforms previous fairness measurement techniques in unawareness scenarios.

Abstract

Algorithms and models are increasingly deployed to inform decisions about people, inevitably affecting their lives. As a consequence, those in charge of developing these models must carefully evaluate their impact on different groups of people and favour group fairness, that is, ensure that groups determined by sensitive demographic attributes, such as race or sex, are not treated unjustly. To achieve this goal, the availability (awareness) of these demographic attributes to those evaluating the impact of these models is fundamental. Unfortunately, collecting and storing these attributes is often in conflict with industry practices and legislation on data minimisation and privacy. For this reason, it can be hard to measure the group fairness of trained models, even from within the companies developing them. In this work, we tackle the problem of measuring group fairness under unawareness of sensitive attributes, by using techniques from quantification, a supervised learning task concerned with directly providing group-level prevalence estimates (rather than individual-level class labels). We show that quantification approaches are particularly suited to tackle the fairness-under-unawareness problem, as they are robust to inevitable distribution shifts while at the same time decoupling the (desirable) objective of measuring group fairness from the (undesirable) side effect of allowing the inference of sensitive attributes of individuals. More in detail, we show that fairness under unawareness can be cast as a quantification problem and solved with proven methods from the quantification literature. We show that these methods outperform previous approaches to measure demographic parity in five experimental protocols, corresponding to important challenges that complicate the estimation of classifier fairness under unawareness.