Who Judges Matters: Measuring Family-Conditioned Preference in LLM-as-Judge Panels
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Abstract (arXiv)
Who the judge is can affect an LLM-as-judge result, but measuring that effect without confusing it with candidate quality is difficult. We study four open-weight families (Llama 3.1, Qwen 2.5, Gemma 2, and Yi 1.5) in a fully crossed pairwise design with 9,312 judgments. A common per-family statistic is strongly confounded with candidate quality and correlates with Bradley-Terry ability at r = 0.95. We derive a corrected estimator that holds the candidate family fixed and compares judges. All four families then show a positive same-family lift (3.4-8.4 percentage points), with global FPS 0.067 (95% CI [0.053, 0.084], permutation p = 0.0002). The effect remains under panel-based quality controls, an independent human-consensus anchor, and a float16 judging replication. Judge-side likelihood is closely related to the effect: adding likelihood advantage reduces the controlled coefficient by 61%, which we treat as descriptive attenuation rather than causal mediation. Position is a separate failure mode. Across the panel, 55.4% of AB/BA pairs reverse, and reversal above 50% is incompatible with a simple independent content-noise model. Relative to a family-balanced reference, panel composition changes 18.5% of pairwise outcomes. A complete reproducibility archive has been prepared for public release.
Key facts. Cited by 1 paper in the map (data through 7 Oct 2026). Builds on 22 of its 32 references that are in the map. First posted on arXiv 15 Sep 2026.
Builds on
22 of 32 references.
References · 22
- 2023Judging LLM-as-a-Judge with MT-Bench and Chatbot Arenacited by 8,393
- 2023Large Language Models are not Fair Evaluatorscited by 1,050
- 2024Length-Controlled AlpacaEval: A Simple Way to Debias Automatic Evaluatorscited by 865
- 2024LLM Evaluators Recognize and Favor Their Own Generationscited by 651
- 2024Replacing Judges with Juries: Evaluating LLM Generations with a Panel of Diverse Modelscited by 301
- 2024Judging the Judges: A Systematic Study of Position Bias in LLM-as-a-Judgecited by 249
- 2024Self-Preference Bias in LLM-as-a-Judgecited by 248
- 2024WildBench: Benchmarking LLMs with Challenging Tasks from Real Users in the Wildcited by 211
- 2024Large Language Models are Inconsistent and Biased Evaluatorscited by 146
- 2025Preference Leakage: A Contamination Problem in LLM-as-a-judgecited by 119
- 2023LLMs as Narcissistic Evaluators: When Ego Inflates Evaluation Scorescited by 88
- 2025Great Models Think Alike and this Undermines AI Oversightcited by 53
10 more
- 2025Do LLM Evaluators Prefer Themselves for a Reason?cited by 38
- 2025Play Favorites: A Statistical Method to Measure Self-Bias in LLM-as-a-Judgecited by 35
- 2025Beyond the Surface: Measuring Self-Preference in LLM Judgmentscited by 30
- 2026Nine Judges, Two Effective Votes: Correlated Errors Undermine LLM Evaluation Panelscited by 21
- 2026Quantifying and Mitigating Self-Preference Bias of LLM Judgescited by 9
- 2026Judging the Judges: A Systematic Evaluation of Bias Mitigation Strategies in LLM-as-a-Judge Pipelinescited by 7
- 2026LLM Judges Have Dark Current: A Psychometric Datasheet for LLM-as-a-Judge Evaluationcited by 6
- 2026When the Judge Changes, So Does the Measurement: Auditing LLM-as-Judge Reliabilitycited by 6
- 2026QEDBENCH: Quantifying the Alignment Gap in Automated Evaluation of University-Level Mathematical Proofscited by 3
- 2026JudgeArena: A Unified Framework for Reproducible LLM-Judge Evaluationcited by 2
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Citing papers per year: 2026: 1.
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- 2026Opening LLM Judges: Recovering Preference Signals Beyond the Final Verdict
- 2026How Much Do LLM-as-a-Judge Design Choices Matter? A Systematic Comparison of Prompt Designs, Rating Scales, and Models
- 2024JudgeBench: A Benchmark for Evaluating LLM-based Judges
- 2026The Coin Flip Judge? Reliability and Bias in LLM-as-a-Judge Evaluation
- 2026Calibrate, Don't Curate: Label-Efficient Estimation from Noisy LLM Judges
- 2026Rethinking Verbalized Confidence for LLM-as-a-Judge: A Compatibility Shift on Post-2025 Proprietary Models
- 2026The Geometry of LLM-as-Judge: Why Inter-LLM Consensus Is Not Human Alignment