From Benchmarking to Failure Diagnosis: Diagnosing Classical Chinese Understanding in LLMs via IRT and Error Attribution

Jiong Wang, Tengju Li, Shengquan Yu


Abstract
Literary Chinese reading comprehension is a challenging task for large language models (LLMs), requiring understanding of implicit meanings, contextual reasoning, and discourse-level integration in a low-resource setting. However, existing evaluations rely primarily on aggregate accuracy, which provides limited insight into model capabilities, error sources, and reliability under uncertainty. We propose DELit, a diagnostic evaluation framework that moves beyond aggregate metrics by introducing a hierarchical capability–error taxonomy, a Deep-MIRT-based ability estimation model, and a capability-decoupled residual analysis for behavioral diagnosis. Together, these components enable fine-grained interpretation of model performance at both capability and error-type levels. Experiments on mainstream LLMs reveal that (i) discourse-level understanding remains a consistent bottleneck despite strong performance on local semantic tasks; (ii) similar overall accuracy can correspond to substantially different capability profiles; and (iii) overconfident errors on difficult items concentrate on logically constrained reasoning, highlighting reliability risks that are not captured by standard evaluation metrics.
Anthology ID:
2026.findings-emnlp.618
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
12991–13005
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.618/
DOI:
10.18653/2026.findings-emnlp.618
Bibkey:
Cite (ACL):
Jiong Wang, Tengju Li, and Shengquan Yu. 2026. From Benchmarking to Failure Diagnosis: Diagnosing Classical Chinese Understanding in LLMs via IRT and Error Attribution. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 12991–13005, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
From Benchmarking to Failure Diagnosis: Diagnosing Classical Chinese Understanding in LLMs via IRT and Error Attribution (Wang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.618.pdf