EpiQAL: Benchmarking Large Language Models in Epidemiological Question Answering and Reasoning

Mingyang Wei, Dehai Min, Zewen Liu, Yuzhang Xie, Guanchen Wu, Ziyang Zhang, Carl Yang, Max SY Lau, Qi He, Lu Cheng, Wei Jin


Abstract
Reliable epidemiological reasoning requires synthesizing study evidence to infer disease burden, transmission dynamics, and intervention effects at the population level. Existing medical question answering benchmarks primarily emphasize clinical knowledge or patient-level reasoning, yet few systematically evaluate evidence-grounded epidemiological inference. We present EpiQAL, to our knowledge the first diagnostic benchmark for epidemiological question answering over research literature, comprising three subsets built from open-access articles across diverse diseases. The three subsets progressively test factual recall, multi-step inference, and conclusion reconstruction under incomplete information, and are constructed through a quality-controlled pipeline combining taxonomy guidance, multi-model verification, and difficulty screening. Experiments on fifteen models spanning open-source and proprietary systems reveal that current LLMs show limited performance on epidemiological reasoning, with multi-step inference posing the greatest challenge. Model rankings shift across subsets, and scale alone does not predict success. Chain-of-Thought prompting benefits multi-step inference but yields mixed results elsewhere. EpiQAL provides fine-grained diagnostic signals for evidence-grounding, inferential reasoning, and conclusion reconstruction.
Anthology ID:
2026.emnlp-main.2103
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:
47858–47892
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2103/
DOI:
Bibkey:
Cite (ACL):
Mingyang Wei, Dehai Min, Zewen Liu, Yuzhang Xie, Guanchen Wu, Ziyang Zhang, Carl Yang, Max SY Lau, Qi He, Lu Cheng, and Wei Jin. 2026. EpiQAL: Benchmarking Large Language Models in Epidemiological Question Answering and Reasoning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 47858–47892, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
EpiQAL: Benchmarking Large Language Models in Epidemiological Question Answering and Reasoning (Wei et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2103.pdf