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A Benchmark for Client-level Fairness in Federated Learning
Proceedings of Fourth European Workshop on Algorithmic Fairness, PMLR 294:434-438, 2025.
Abstract
Federated Learning (FL) enables collaborative model training while preserving participating clients’ local data privacy. However, the diverse data distributions across different clients can exacerbate fairness issues, as biases in client data may propagate across the Federation. Although various approaches have been proposed to enhance fairness in FL, they typically focus on mitigating the bias of a single binary-sensitive attribute. This narrow focus often overlooks the complexity introduced by clients with conflicting or diverse fairness objectives. Such clients may contribute to the Federation without experiencing any improvement in their model’s performance or fairness regarding their specific sensitive attributes. To evaluate Fair FL methods for global and individual client fairness in a reproducible and reliable manner, the need for standardized datasets becomes apparent. In this paper, we propose a preliminary framework to create benchmarking datasets that allow researchers and developers to evaluate Fair FL methods. These benchmarking datasets include various heterogeneous client settings with regard to data bias of sensitive attributes for assessing fairness at the global and individual level. Additionally, we provide information on how to evaluate results obtained with these benchmarking datasets.