Safe Fairness Guarantees Without Demographics in Classification: Spectral Uncertainty Set Perspective

Fuente: arXiv
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Autores principales: Barrainkua, Ainhize, Mazuelas, Santiago, Quadrianto, Novi, Lozano, Jose A.
Formato: Preprint
Publicado: 2026
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author Barrainkua, Ainhize
Mazuelas, Santiago
Quadrianto, Novi
Lozano, Jose A.
author_facet Barrainkua, Ainhize
Mazuelas, Santiago
Quadrianto, Novi
Lozano, Jose A.
contents As automated classification systems become increasingly prevalent, concerns have emerged over their potential to reinforce and amplify existing societal biases. In the light of this issue, many methods have been proposed to enhance the fairness guarantees of classifiers. Most of the existing interventions assume access to group information for all instances, a requirement rarely met in practice. Fairness without access to demographic information has often been approached through robust optimization techniques,which target worst-case outcomes over a set of plausible distributions known as the uncertainty set. However, their effectiveness is strongly influenced by the chosen uncertainty set. In fact, existing approaches often overemphasize outliers or overly pessimistic scenarios, compromising both overall performance and fairness. To overcome these limitations, we introduce SPECTRE, a minimax-fair method that adjusts the spectrum of a simple Fourier feature mapping and constrains the extent to which the worst-case distribution can deviate from the empirical distribution. We perform extensive experiments on the American Community Survey datasets involving 20 states. The safeness of SPECTRE comes as it provides the highest average values on fairness guarantees together with the smallest interquartile range in comparison to state-of-the-art approaches, even compared to those with access to demographic group information. In addition, we provide a theoretical analysis that derives computable bounds on the worst-case error for both individual groups and the overall population, as well as characterizes the worst-case distributions responsible for these extremal performances
format Preprint
id arxiv_https___arxiv_org_abs_2602_11785
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Safe Fairness Guarantees Without Demographics in Classification: Spectral Uncertainty Set Perspective
Barrainkua, Ainhize
Mazuelas, Santiago
Quadrianto, Novi
Lozano, Jose A.
Machine Learning
Artificial Intelligence
As automated classification systems become increasingly prevalent, concerns have emerged over their potential to reinforce and amplify existing societal biases. In the light of this issue, many methods have been proposed to enhance the fairness guarantees of classifiers. Most of the existing interventions assume access to group information for all instances, a requirement rarely met in practice. Fairness without access to demographic information has often been approached through robust optimization techniques,which target worst-case outcomes over a set of plausible distributions known as the uncertainty set. However, their effectiveness is strongly influenced by the chosen uncertainty set. In fact, existing approaches often overemphasize outliers or overly pessimistic scenarios, compromising both overall performance and fairness. To overcome these limitations, we introduce SPECTRE, a minimax-fair method that adjusts the spectrum of a simple Fourier feature mapping and constrains the extent to which the worst-case distribution can deviate from the empirical distribution. We perform extensive experiments on the American Community Survey datasets involving 20 states. The safeness of SPECTRE comes as it provides the highest average values on fairness guarantees together with the smallest interquartile range in comparison to state-of-the-art approaches, even compared to those with access to demographic group information. In addition, we provide a theoretical analysis that derives computable bounds on the worst-case error for both individual groups and the overall population, as well as characterizes the worst-case distributions responsible for these extremal performances
title Safe Fairness Guarantees Without Demographics in Classification: Spectral Uncertainty Set Perspective
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2602.11785