LLM Judges Can Be Too Generous When There Is No Reference Answer
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Abstract (arXiv)
LLM judges are increasingly being used to evaluate open-ended model responses, often in no-reference settings where a ground-truth answer is unavailable. However, can they reliably assess in such evaluation setups? We explore this question in this paper through a two stage pipeline with a) calibration experiments that assess the judge model's knowledge of the task it is evaluating, and b) sensitivity experiments that assess how the judge model's performance is impacted by the presence and positioning of the reference answer in the prompt. Across experiments covering three languages, we show that the judge models we evaluated tend to over-credit incorrect answers in the absence of a reference answer, and adding reference answer information to the prompt flips the judge model's correct/incorrect decisions by as much as 85% in some experimental settings. Comparison with a subset of human annotations shows that these reference-driven changes generally align with human judgments. Our results emphasize the need for calibrating the LLM judges with a sample with reference-aware evaluation before using them in reference-free setups reliably, and our methodology provides a blueprint for researchers and practitioners in doing such calibration of LLM judges for other tasks.
Key facts. Cited by 4 papers in the map (data through 14 Oct 2026). Builds on 34 of its 50 references that are in the map. First posted on arXiv 14 Jul 2026.
Builds on
34 of 50 references.
References · 34
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- 2024JudgeBench: A Benchmark for Evaluating LLM-based Judgescited by 318
22 more
- 2023Evaluating Large Language Models at Evaluating Instruction Followingcited by 302
- 2024Judging the Judges: A Systematic Study of Position Bias in LLM-as-a-Judgecited by 269
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- 2025Does Context Matter? ContextualJudgeBench for Evaluating LLM-based Judges in Contextual Settingscited by 24
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Built on by
Citing papers per year: 2026: 4.
4 papers.
- 2026Commit-first LLM judging inherits the judge's own errorscited by 2
- 2026Maintaining Benchmarks Against Increasingly Capable Agents: Detection and Remediation of Unearned Passescited by 1
- 2026From Migration to Calibration: Aligning Agents with Deployment Requirementscited by 0
- 2026Judges Follow the Reference: The Derivation Gap in Verifying Tool-Call Argumentscited by 0
- 2026Judges Follow the Reference: The Derivation Gap in Verifying Tool-Call Arguments13 Oct 2026
- 2026From Migration to Calibration: Aligning Agents with Deployment Requirements28 Sep 2026
- 2026Maintaining Benchmarks Against Increasingly Capable Agents: Detection and Remediation of Unearned Passes28 Sep 2026
- 2026Commit-first LLM judging inherits the judge's own errors31 Aug 2026