  Evaluating Large Language Models (LLMs) in open-ended scenarios is
challenging because existing benchmarks and metrics can not measure them
comprehensively. To address this problem, we propose to fine-tune LLMs as
scalable judges (JudgeLM) to evaluate LLMs efficiently and effectively in
open-ended benchmarks. We first propose a comprehensive, large-scale,
high-quality dataset containing task seeds, LLMs-generated answers, and
GPT-4-generated judgments for fine-tuning high-performance judges, as well as a
new benchmark for evaluating the judges. We train JudgeLM at different scales
from 7B, 13B, to 33B parameters, and conduct a systematic analysis of its
capabilities and behaviors. We then analyze the key biases in fine-tuning LLM
as a judge and consider them as position bias, knowledge bias, and format bias.
To address these issues, JudgeLM introduces a bag of techniques including swap
augmentation, reference support, and reference drop, which clearly enhance the
judge's performance. JudgeLM obtains the state-of-the-art judge performance on
both the existing PandaLM benchmark and our proposed new benchmark. Our JudgeLM
is efficient and the JudgeLM-7B only needs 3 minutes to judge 5K samples with 8
A100 GPUs. JudgeLM obtains high agreement with the teacher judge, achieving an
agreement exceeding 90% that even surpasses human-to-human agreement. JudgeLM
also demonstrates extended capabilities in being judges of the single answer,
multimodal models, multiple answers, and multi-turn chat.
