Adding Chocolate to Mint: Mitigating Metric Interference in Machine Translation

Fuente: arXiv
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Main Authors: Pombal, José, Guerreiro, Nuno M., Rei, Ricardo, Martins, André F. T.
Format: Preprint
Published: 2025
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author Pombal, José
Guerreiro, Nuno M.
Rei, Ricardo
Martins, André F. T.
author_facet Pombal, José
Guerreiro, Nuno M.
Rei, Ricardo
Martins, André F. T.
contents As automatic metrics become increasingly stronger and widely adopted, the risk of unintentionally "gaming the metric" during model development rises. This issue is caused by metric interference (MINT), i.e., the use of the same or related metrics for both model tuning and evaluation. MINT can misguide practitioners into being overoptimistic about the performance of their systems: as system outputs become a function of the interfering metric, their estimated quality loses correlation with human judgments. In this work, we analyze two common cases of MINT in machine translation-related tasks: filtering of training data, and decoding with quality signals. Importantly, we find that MINT strongly distorts instance-level metric scores, even when metrics are not directly optimized for-questioning the common strategy of leveraging a different, yet related metric for evaluation that is not used for tuning. To address this problem, we propose MINTADJUST, a method for more reliable evaluation under MINT. On the WMT24 MT shared task test set, MINTADJUST ranks translations and systems more accurately than state-of-the-art metrics across a majority of language pairs, especially for high-quality systems. Furthermore, MINTADJUST outperforms AUTORANK, the ensembling method used by the organizers.
format Preprint
id arxiv_https___arxiv_org_abs_2503_08327
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Adding Chocolate to Mint: Mitigating Metric Interference in Machine Translation
Pombal, José
Guerreiro, Nuno M.
Rei, Ricardo
Martins, André F. T.
Computation and Language
Artificial Intelligence
As automatic metrics become increasingly stronger and widely adopted, the risk of unintentionally "gaming the metric" during model development rises. This issue is caused by metric interference (MINT), i.e., the use of the same or related metrics for both model tuning and evaluation. MINT can misguide practitioners into being overoptimistic about the performance of their systems: as system outputs become a function of the interfering metric, their estimated quality loses correlation with human judgments. In this work, we analyze two common cases of MINT in machine translation-related tasks: filtering of training data, and decoding with quality signals. Importantly, we find that MINT strongly distorts instance-level metric scores, even when metrics are not directly optimized for-questioning the common strategy of leveraging a different, yet related metric for evaluation that is not used for tuning. To address this problem, we propose MINTADJUST, a method for more reliable evaluation under MINT. On the WMT24 MT shared task test set, MINTADJUST ranks translations and systems more accurately than state-of-the-art metrics across a majority of language pairs, especially for high-quality systems. Furthermore, MINTADJUST outperforms AUTORANK, the ensembling method used by the organizers.
title Adding Chocolate to Mint: Mitigating Metric Interference in Machine Translation
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2503.08327