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

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

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.

Computation and Language (cs.CL)

arXiv:2609.01369 [cs.CL]

(or arXiv:2609.01369v1 [cs.CL] for this version)

https://doi.org/10.48550/arXiv.2609.01369 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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