Investigating Non-Transitivity in LLM-as-a-Judge

Fuente: arXiv
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Main Authors: Xu, Yi, Ruis, Laura, Rocktäschel, Tim, Kirk, Robert
Format: Preprint
Published: 2025
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author Xu, Yi
Ruis, Laura
Rocktäschel, Tim
Kirk, Robert
author_facet Xu, Yi
Ruis, Laura
Rocktäschel, Tim
Kirk, Robert
contents Automatic evaluation methods based on large language models (LLMs) are emerging as the standard tool for assessing the instruction-following abilities of LLM-based agents. The most common method in this paradigm, pairwise comparisons with a baseline model, critically depends on the assumption of transitive preferences. However, the validity of this assumption remains largely unexplored. In this study, we investigate the presence of non-transitivity within the AlpacaEval framework and analyze its effects on model rankings. We find that LLM judges exhibit non-transitive preferences, leading to rankings that are sensitive to the choice of the baseline model. To mitigate this issue, we show that round-robin tournaments combined with Bradley-Terry models of preference can produce more reliable rankings. Notably, our method increases both the Spearman correlation and the Kendall correlation with Chatbot Arena (95.0% -> 96.4% and 82.1% -> 86.3% respectively). To address the computational cost of round-robin tournaments, we propose Swiss-Wise Iterative Matchmaking (Swim) tournaments, using a dynamic matching strategy to capture the benefits of round-robin tournaments while maintaining computational efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2502_14074
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Investigating Non-Transitivity in LLM-as-a-Judge
Xu, Yi
Ruis, Laura
Rocktäschel, Tim
Kirk, Robert
Artificial Intelligence
Computation and Language
Machine Learning
Automatic evaluation methods based on large language models (LLMs) are emerging as the standard tool for assessing the instruction-following abilities of LLM-based agents. The most common method in this paradigm, pairwise comparisons with a baseline model, critically depends on the assumption of transitive preferences. However, the validity of this assumption remains largely unexplored. In this study, we investigate the presence of non-transitivity within the AlpacaEval framework and analyze its effects on model rankings. We find that LLM judges exhibit non-transitive preferences, leading to rankings that are sensitive to the choice of the baseline model. To mitigate this issue, we show that round-robin tournaments combined with Bradley-Terry models of preference can produce more reliable rankings. Notably, our method increases both the Spearman correlation and the Kendall correlation with Chatbot Arena (95.0% -> 96.4% and 82.1% -> 86.3% respectively). To address the computational cost of round-robin tournaments, we propose Swiss-Wise Iterative Matchmaking (Swim) tournaments, using a dynamic matching strategy to capture the benefits of round-robin tournaments while maintaining computational efficiency.
title Investigating Non-Transitivity in LLM-as-a-Judge
topic Artificial Intelligence
Computation and Language
Machine Learning
url https://arxiv.org/abs/2502.14074