Training an LLM-as-a-Judge Model: Pipeline, Insights, and Practical Lessons

Fuente: arXiv
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Autores principales: Hu, Renjun, Cheng, Yi, Meng, Libin, Xia, Jiaxin, Zong, Yi, Shi, Xing, Lin, Wei
Formato: Preprint
Publicado: 2025
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author Hu, Renjun
Cheng, Yi
Meng, Libin
Xia, Jiaxin
Zong, Yi
Shi, Xing
Lin, Wei
author_facet Hu, Renjun
Cheng, Yi
Meng, Libin
Xia, Jiaxin
Zong, Yi
Shi, Xing
Lin, Wei
contents The rapid advancement of large language models (LLMs) has opened new possibilities for their adoption as evaluative judges. This paper introduces Themis, a fine-tuned LLM judge that delivers sophisticated context-aware evaluations. We provide a comprehensive overview of the development pipeline for Themis, highlighting its scenario-dependent evaluation prompts and two novel methods for controlled instruction generation. These designs enable Themis to effectively distill evaluative skills from teacher models, while retaining flexibility for continuous development. We introduce two human-labeled benchmarks for meta-evaluation, demonstrating that Themis can achieve high alignment with human preferences in an economical manner. Additionally, we explore insights into the LLM-as-a-judge paradigm, revealing nuances in performance and the varied effects of reference answers. Notably, we observe that pure knowledge distillation from strong LLMs, though common, does not guarantee performance improvement through scaling. We propose a mitigation strategy based on instruction-following difficulty. Furthermore, we provide practical guidelines covering data balancing, prompt customization, multi-objective training, and metric aggregation. We aim for our method and findings, along with the fine-tuning data, benchmarks, and model checkpoints, to support future research and development in this area.
format Preprint
id arxiv_https___arxiv_org_abs_2502_02988
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Training an LLM-as-a-Judge Model: Pipeline, Insights, and Practical Lessons
Hu, Renjun
Cheng, Yi
Meng, Libin
Xia, Jiaxin
Zong, Yi
Shi, Xing
Lin, Wei
Computation and Language
Artificial Intelligence
Machine Learning
The rapid advancement of large language models (LLMs) has opened new possibilities for their adoption as evaluative judges. This paper introduces Themis, a fine-tuned LLM judge that delivers sophisticated context-aware evaluations. We provide a comprehensive overview of the development pipeline for Themis, highlighting its scenario-dependent evaluation prompts and two novel methods for controlled instruction generation. These designs enable Themis to effectively distill evaluative skills from teacher models, while retaining flexibility for continuous development. We introduce two human-labeled benchmarks for meta-evaluation, demonstrating that Themis can achieve high alignment with human preferences in an economical manner. Additionally, we explore insights into the LLM-as-a-judge paradigm, revealing nuances in performance and the varied effects of reference answers. Notably, we observe that pure knowledge distillation from strong LLMs, though common, does not guarantee performance improvement through scaling. We propose a mitigation strategy based on instruction-following difficulty. Furthermore, we provide practical guidelines covering data balancing, prompt customization, multi-objective training, and metric aggregation. We aim for our method and findings, along with the fine-tuning data, benchmarks, and model checkpoints, to support future research and development in this area.
title Training an LLM-as-a-Judge Model: Pipeline, Insights, and Practical Lessons
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2502.02988