Justice in Judgment: Unveiling (Hidden) Bias in LLM-assisted Peer Reviews

• URL: http://arxiv.org/abs/2509.13400v4
• Date: Fri, 26 Sep 2025 11:58:54 GMT
• Title: Justice in Judgment: Unveiling (Hidden) Bias in LLM-assisted Peer Reviews
• Authors: Sai Suresh Macharla Vasu, Ivaxi Sheth, Hui-Po Wang, Ruta Binkyte, Mario Fritz,
• Abstract summary: We investigate bias in large language models (LLMs)-generated peer reviews by conducting experiments on sensitive metadata.<n>Our analysis consistently shows affiliation bias favoring institutions highly ranked on common academic rankings.<n>We uncover implicit biases that become more evident with token-based soft ratings.
• Score: 38.50822587716282
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The adoption of large language models (LLMs) is transforming the peer review process, from assisting reviewers in writing more detailed evaluations to generating entire reviews automatically. While these capabilities offer exciting opportunities, they also raise critical concerns about fairness and reliability. In this paper, we investigate bias in LLM-generated peer reviews by conducting controlled experiments on sensitive metadata, including author affiliation and gender. Our analysis consistently shows affiliation bias favoring institutions highly ranked on common academic rankings. Additionally, we find some gender preferences, which, even though subtle in magnitude, have the potential to compound over time. Notably, we uncover implicit biases that become more evident with token-based soft ratings.

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