Validity-Aware Assessment of LLM Value Orientation via Subset Item Response Theory

Qinlin Zhao, Xiaoyuan Yi, Jing Yao, Muhua Huang, Defu Lian, Xing Xie


Abstract
Measuring the value orientations of LLMs is helpful for diagnosing model risk and understanding their misalignment behavior. However, existing value benchmarks are often AI-generated and lack validity verification, leading to noisy and unreliable results. Inspired by Psychometrics, we propose a novel Subset Item Response Theory (S-IRT) model for assessing LLMs’ values under any value theories. S-IRT directly models the subset of values jointly expressed in each LLM response, rather than reducing responses to binary outcomes as in traditional IRT-based ability assessment. Meanwhile, it jointly estimates the LLM’s latent values and captures the relative priorities among them. Based on it, we further design a tailored information reward that estimates the information gain of each item in reducing uncertainty about the evaluated model’s value, and thus helps select a small set of high-quality items from existing benchmarks. Extensive experiments on 23 popular LLMs and three value systems (21 value dimensions) demonstrate S-IRT can be applied to multiple value systems simultaneously and improve evaluation reliability and validity. The information reward also helps reduce the number of questions to as few as 200 while preserving comparable evaluation effectiveness.
Anthology ID:
2026.emnlp-main.2578
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
58592–58615
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2578/
DOI:
Bibkey:
Cite (ACL):
Qinlin Zhao, Xiaoyuan Yi, Jing Yao, Muhua Huang, Defu Lian, and Xing Xie. 2026. Validity-Aware Assessment of LLM Value Orientation via Subset Item Response Theory. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 58592–58615, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Validity-Aware Assessment of LLM Value Orientation via Subset Item Response Theory (Zhao et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.2578.pdf