Robust AI Evaluation through Maximal Lotteries

Fuente: arXiv
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Auteurs principaux: Khalaf, Hadi, Wang, Serena L., Halpern, Daniel, Shapira, Itai, Calmon, Flavio du Pin, Procaccia, Ariel D.
Format: Preprint
Publié: 2026
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author Khalaf, Hadi
Wang, Serena L.
Halpern, Daniel
Shapira, Itai
Calmon, Flavio du Pin
Procaccia, Ariel D.
author_facet Khalaf, Hadi
Wang, Serena L.
Halpern, Daniel
Shapira, Itai
Calmon, Flavio du Pin
Procaccia, Ariel D.
contents The standard way to evaluate language models on subjective tasks is through pairwise comparisons: an annotator chooses the "better" of two responses to a prompt. Leaderboards aggregate these comparisons into a single Bradley-Terry (BT) ranking, forcing heterogeneous preferences into a total order and violating basic social-choice desiderata. In contrast, social choice theory provides an alternative approach called maximal lotteries, which aggregates pairwise preferences without imposing any assumptions on their structure. However, we show that maximal lotteries are highly sensitive to preference heterogeneity and can favor models that severely underperform on specific tasks or user subpopulations. We introduce robust lotteries that optimize worst-case performance under plausible shifts in the preference data. On large-scale preference datasets, robust lotteries provide more reliable win rate guarantees across the annotator distribution and recover a stable set of top-performing models. By moving from rankings to pluralistic sets of winners, robust lotteries offer a principled step toward an ecosystem of complementary AI systems that serve the full spectrum of human preferences.
format Preprint
id arxiv_https___arxiv_org_abs_2602_21297
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Robust AI Evaluation through Maximal Lotteries
Khalaf, Hadi
Wang, Serena L.
Halpern, Daniel
Shapira, Itai
Calmon, Flavio du Pin
Procaccia, Ariel D.
Machine Learning
The standard way to evaluate language models on subjective tasks is through pairwise comparisons: an annotator chooses the "better" of two responses to a prompt. Leaderboards aggregate these comparisons into a single Bradley-Terry (BT) ranking, forcing heterogeneous preferences into a total order and violating basic social-choice desiderata. In contrast, social choice theory provides an alternative approach called maximal lotteries, which aggregates pairwise preferences without imposing any assumptions on their structure. However, we show that maximal lotteries are highly sensitive to preference heterogeneity and can favor models that severely underperform on specific tasks or user subpopulations. We introduce robust lotteries that optimize worst-case performance under plausible shifts in the preference data. On large-scale preference datasets, robust lotteries provide more reliable win rate guarantees across the annotator distribution and recover a stable set of top-performing models. By moving from rankings to pluralistic sets of winners, robust lotteries offer a principled step toward an ecosystem of complementary AI systems that serve the full spectrum of human preferences.
title Robust AI Evaluation through Maximal Lotteries
topic Machine Learning
url https://arxiv.org/abs/2602.21297