MetaDocEval: A Contrastive Framework for Evaluating Machine Translation Metrics at the Document-Level

Nicolas Dahan, Rachel Bawden, François Yvon


Abstract
Recent advances in neural machine translation (MT) have spurred increased interest in evaluating translations beyond the sentence level, making it possible to assess discourse-level phenomena related to coherence and consistency. While existing metrics can be applied to multi-sentence spans, it remains unclear whether their scores truly capture document-level quality. We introduce MetaDocEval, an automatic contrastive test set for evaluating MT metrics across three language pairs (en–fr, en–es, en–de) when applied at the document-level. It targets a range of discourse-level phenomena and potential problems linked to translation at the document level. To evaluate how metrics behave as a function of context size, we apply them under a sliding-window protocol, varying the input from single sentences up to full documents. Our experiments show that no current metric genuinely captures document-level coherence: reference-based metrics overfit lexical overlap, reference+source metrics gain little from added context, reference-free encoders show brief context sensitivity before degrading on longer spans, and LLM-based scorers collapse beyond short inputs. A key finding is that reference access can be actively harmful for detecting discourse-level errors. Using short windows (≈ 3 sentences) offers the best trade-off between discourse error detection and score dilution.
Anthology ID:
2026.eamt-1.19
Volume:
Proceedings of the 26th Annual Conference of the European Association for Machine Translation (Volume 1)
Month:
June
Year:
2026
Address:
Tilburg, The Netherlands
Editors:
Dimitar Shterionov, Eva Vanmassenhove, Mirella De Sisto, Fred Blain, Javad Pourmostafa Roshan Sharami, Lisa Lepp, Chiara Manna, Argentina Anna Rescigno, Alina Karakanta, Ayla Rigouts Terryn, Manuel Lardelli, Natalia Resende, Elena Murgolo, Janiça Hackenbuchner, Anna Zaretskaya, Miquel Esplà-Gomis, Thierry Etchegoyhen, Dagmar Gromann, Rachel Bawden, Barry Haddow, Sara Szoc, Mikel Forcada, Helena Moniz
Venue:
EAMT
SIG:
Publisher:
European Association for Machine Translation
Note:
Pages:
268–303
Language:
URL:
https://aclanthology.org/2026.eamt-1.19/
DOI:
Bibkey:
Cite (ACL):
Nicolas Dahan, Rachel Bawden, and François Yvon. 2026. MetaDocEval: A Contrastive Framework for Evaluating Machine Translation Metrics at the Document-Level. In Proceedings of the 26th Annual Conference of the European Association for Machine Translation (Volume 1), pages 268–303, Tilburg, The Netherlands. European Association for Machine Translation.
Cite (Informal):
MetaDocEval: A Contrastive Framework for Evaluating Machine Translation Metrics at the Document-Level (Dahan et al., EAMT 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.eamt-1.19.pdf