MQM Re-Annotation: A Technique for Collaborative Evaluation of Machine Translation
Summary
As machine translation systems improve, noise in human evaluation can hide the real quality differences between them. This paper tests a two-pass variant of MQM, called MQM re-annotation. An expert rater opens a document that already contains error spans and can edit, delete or add errors. The prior spans come from the rater's own earlier pass, from a different human, or from an automatic MQM system. The authors used WMT 2023 Metrics Shared Task News data in Chinese-English and English-German, the Anthea interface, and professional translators as raters. Because no true ground truth exists, they judged quality by agreement between disjoint rater groups.
Raters edited their own annotations the least, other humans' annotations more, and automatic output the most. Most of the gain came from catching errors missed the first time. Re-annotating human ratings raised cross-group agreement. Starting from LLM-produced spans also beat annotating from scratch, at no extra human cost. Human-on-human re-annotation was best overall, but it costs roughly twice the labor. The method is especially useful for building reference data to meta-evaluate span-level metrics.
Key points
- Data: Chinese-English has 247 segments, 25 documents, 16 systems and 8 raters. English-German has 100 segments, 29 documents, 13 systems and 10 raters. Each segment received 3 initial human MQM annotations.
- Automatic systems:
- GEMBA-MQM, which prompts GPT-4.
- An AutoMQM variant built by fine-tuning Gemini 1.0 Pro on WMT 2020–2022 MQM data.
- Both work without a reference translation.
- Agreement metrics: Pairwise Ranking Agreement (PRA) and character F1. On segment-level pairwise agreement:
- Single vs. Single scored 0.511 (zh-en) and 0.574 (en-de).
- Self vs. Other re-annotations reached 0.553 and 0.641.
- Auto vs. Auto re-annotations reached 0.546 and 0.631.
- Artificial spans: Fake Major-severity errors were injected to check whether raters over-trust prior spans. Most were removed, but a few raters often kept them unchanged.
- Release and limits: The data is public in the google/wmt-mqm-human-evaluation repository (generalMT2023). The study covers only expert raters, two reasonably strong automatic systems, and the News domain.
Cite
@inproceedings{riley2026mqm,
title = {{MQM Re-Annotation: A Technique for Collaborative Evaluation of Machine Translation}},
author = {Riley, Parker and Deutsch, Daniel and Finkelstein, Mara and DiIanni, Colten and Juraska, Juraj and Freitag, Markus},
booktitle = {Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)},
year = {2026},
doi = {10.18653/v1/2026.acl-long.1553},
url = {https://doi.org/10.18653/v1/2026.acl-long.1553}
}References
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