How Correct Is Your Answer? A Semantic Correctness Framework for Open QA Evaluation

Elitsa Yotkova, Violeta Kastreva, Petar Velkov, Hristo Boyanov, Dimitar Iliyanov Dimitrov, Preslav Nakov, Ivan Koychev


Abstract
Reliable evaluation of open-ended question answering remains a bottleneck for measuring answer correctness of modern LLMs. Unlike multiple-choice tasks, free-form answers may be correct in many surface forms and may fail in qualitatively different ways, including incompleteness, contradiction, overgeneration, and endorsement of false premises. Existing judgment-based and similarity-based metrics often collapse these distinctions. We address this gap with three reusable contributions. First, we introduce a semantic correctness taxonomy that assigns open-ended answers to eight ordered classes, separating verbose-but-correct answers from those contaminated by hallucinated content. Second, we release CAP-Correctness, an 8.8k-example benchmark spanning widely used QA datasets, and CAP-Statements, an 11k-example dataset for converting question-answer pairs into declarative statements for natural language inference (NLI) training and statement-based evaluation. Third, we introduce CAP (Context-Aware Precision), a reference-based metric that scores question-conditioned statements using bidirectional NLI. Under a monotonicity protocol testing whether metrics respect the taxonomy’s intended ordering, CAP outperforms established baselines.
Anthology ID:
2026.findings-emnlp.1858
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:
39666–39685
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1858/
DOI:
10.18653/2026.findings-emnlp.1858
Bibkey:
Cite (ACL):
Elitsa Yotkova, Violeta Kastreva, Petar Velkov, Hristo Boyanov, Dimitar Iliyanov Dimitrov, Preslav Nakov, and Ivan Koychev. 2026. How Correct Is Your Answer? A Semantic Correctness Framework for Open QA Evaluation. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 39666–39685, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
How Correct Is Your Answer? A Semantic Correctness Framework for Open QA Evaluation (Yotkova et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1858.pdf