Reasoning Model Is Superior LLM-Judge, Yet Suffers from Biases

Fuente: arXiv
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Auteurs principaux: Huang, Hui, Wu, Xuanxin, Yang, Muyun, Arase, Yuki
Format: Preprint
Publié: 2026
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author Huang, Hui
Wu, Xuanxin
Yang, Muyun
Arase, Yuki
author_facet Huang, Hui
Wu, Xuanxin
Yang, Muyun
Arase, Yuki
contents This paper presents the first systematic comparison investigating whether Large Reasoning Models (LRMs) are superior judges to non-reasoning LLMs. Our empirical analysis yields four key findings: 1) LRMs outperform non-reasoning LLMs in terms of judgment accuracy, particularly on reasoning-intensive tasks; 2) LRMs demonstrate superior evaluation instruction-following capabilities; 3) LRMs exhibit enhanced robustness against adversarial attacks targeting judgment tasks; 4) However, LRMs still exhibit strong evaluation biases. To mitigate this bias vulnerability, we propose PlanJudge, a lightweight evaluation strategy that prompts the model to generate an explicit evaluation plan before executing the judgment. Despite its simplicity, our experiments demonstrate that PlanJudge significantly mitigates biases in LLM-as-a-Judge while preserving overall judgment accuracy.
format Preprint
id arxiv_https___arxiv_org_abs_2601_03630
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Reasoning Model Is Superior LLM-Judge, Yet Suffers from Biases
Huang, Hui
Wu, Xuanxin
Yang, Muyun
Arase, Yuki
Computation and Language
This paper presents the first systematic comparison investigating whether Large Reasoning Models (LRMs) are superior judges to non-reasoning LLMs. Our empirical analysis yields four key findings: 1) LRMs outperform non-reasoning LLMs in terms of judgment accuracy, particularly on reasoning-intensive tasks; 2) LRMs demonstrate superior evaluation instruction-following capabilities; 3) LRMs exhibit enhanced robustness against adversarial attacks targeting judgment tasks; 4) However, LRMs still exhibit strong evaluation biases. To mitigate this bias vulnerability, we propose PlanJudge, a lightweight evaluation strategy that prompts the model to generate an explicit evaluation plan before executing the judgment. Despite its simplicity, our experiments demonstrate that PlanJudge significantly mitigates biases in LLM-as-a-Judge while preserving overall judgment accuracy.
title Reasoning Model Is Superior LLM-Judge, Yet Suffers from Biases
topic Computation and Language
url https://arxiv.org/abs/2601.03630