English

Selection of the Best Policy under Fairness Constraints for Subpopulations

Machine Learning 2026-05-12 v1

Abstract

Many high-stakes decisions in health care, public policy, and clinical development require committing to a single policy that will be applied uniformly across a heterogeneous population. Regulatory and fairness standards sometime requires that the chosen policy performs adequately in every pre-specified subpopulation, not only on average. We formalize this as a Selection of the Best with Fairness Constraints (SBFC) problem, in order to identify the policy with the highest average performance among those policies that meet a minimum per-subpopulation threshold. We establish an instance-specific lower bound on sample complexity of the SBFC problem. We then develop a Track-and-Stop with Constraints on Subpopulation (T-a-S-CS) algorithm that achieves the lower bound asymptotically. We extend the framework to general closed-set and penalty-based fairness specifications with matching guarantees. Numerical experiments and a case study using the International Stroke Trial demonstrate substantial efficiency gains over policy-level allocation baselines.

Keywords

Cite

@article{arxiv.2605.09945,
  title  = {Selection of the Best Policy under Fairness Constraints for Subpopulations},
  author = {Tingyu Zhu and Yuhang Wu and Zeyu Zheng},
  journal= {arXiv preprint arXiv:2605.09945},
  year   = {2026}
}