arXiv Machine Learning By Saman Jayasinghe, Sean Walton, Alma Rahat, Andy Gray, Chris Wheadon

Alternative Strategies for Active Learning with Bayesian Bradley Terry Model

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The paper introduces a Bayesian Bradley‑Terry model (BBTM) that employs Polya‑Gamma data augmentation for efficient Gibbs sampling and quantifies uncertainty in latent abilities and ranks. Three active‑learning strategies based on the knowledge‑gradient principle are proposed, using Kendall’s tau distance, posterior rank entropy, and posterior separation as acquisition functions, with approximate one‑step updates to reduce computational cost. The authors also present Posterior Separation Reliability (PSR) as an internal indicator of ranking reliability, and demonstrate through synthetic experiments that BBTM outperforms preference‑based Bayesian comparative judgement, with the entropy‑based strategy excelling at low‑to‑moderate noise and the posterior‑separation strategy at high noise levels.

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arXiv Statistics ML
Sep 4

Low Rank for Rank: Uncertainty-Aware Task-Specific LLM Ranking under Sparse Pairwise Comparisons

The paper introduces a low‑rank framework for ranking large language models (LLMs) on task‑specific benchmarks using sparse pairwise comparisons. By modeling the task‑by‑model ability matrix as low rank, the method shares information across related tasks while preserving task‑specific differences, and it provides uncertainty‑aware ranking through debiased estimators and simultaneous confidence sets. Experiments on synthetic data and the Chatbot Arena benchmark demonstrate improved sample efficiency and tighter, better‑calibrated ranking certificates, especially in the sparse comparison regime typical of real LLM evaluations.

By Jiachun Li, David Simchi-Levi, Will Wei Sun