Does task decomposition improve automatic NLG evaluation?

Sebastian Steindl, Nikos Voskarides, Alberto Gasparin, Diego Marcheggiani


Abstract
The LLM-as-a-judge (LLMaJ) framework has emerged as a promising solution for cheap, reproducible, reference-free Natural Language Generation (NLG) evaluation. Prior work seeks to improve LLMaJ by decomposing evaluation tasks into simpler sub-tasks. In this work, we systematically compare LLMaJ methods with and without decomposition on multiple NLG datasets. We find no evidence that LLMaJ with task decomposition leads to performance gains over a fair baseline that does not use decomposition. Instead, we find that previously reported performance gains in decomposition-based LLMaJ stem from using human labels as training data, and not task decomposition itself. Also, we find that, when human labels are available, LLMaJ without using task decomposition can perform comparably to human annotators.
Anthology ID:
2026.emnlp-main.447
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
10288–10301
Language:
URL:
https://aclanthology.org/2026.emnlp-main.447/
DOI:
Bibkey:
Cite (ACL):
Sebastian Steindl, Nikos Voskarides, Alberto Gasparin, and Diego Marcheggiani. 2026. Does task decomposition improve automatic NLG evaluation?. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 10288–10301, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Does task decomposition improve automatic NLG evaluation? (Steindl et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.447.pdf