When Audit Quality Fails to Predict Downstream Utility: Synthetic-Data Selection for Low-Resource Classification

Xuan-Bach Le, Phat T. Tran-Truong, Son Ha Xuan


Abstract
Quality-aware synthetic-data selection assumes that examples rated highly by an LLM judge will help downstream learning. We test this assumption in a controlled replay across two low-resource African-language classification tasks, four languages, and seven selectors. Six selectors retain 64 examples per task-language cell. CoSDA-V2 yields the highest judged label correctness (0.904 versus 0.767 for naive) and the lowest measured shortcut score, but AlpaGasus leads CoSDA-V2 on downstream Macro-F1 in both the main replay (0.202 versus 0.163) and the three-seed refit (0.193 versus 0.157).

Adding the audit’s strict gate to AlpaGasus reduces Macro-F1 by 0.029, driven by one cell where only 31 of 64 candidates survive. Because the gate changes pool composition and training-set size, this comparison measures their joint effect. LESS also falls below naive when unconstrained top-k collapses label balance, but recovers with quotas. At this budget, retention constraints account for more of the observed differences than a consistent ranking advantage. In this replay, audit scores do not reliably predict downstream utility. We therefore recommend reporting both metrics for the same retained sets.
Anthology ID:
2026.findings-emnlp.1184
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
25027–25045
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1184/
DOI:
Bibkey:
Cite (ACL):
Xuan-Bach Le, Phat T. Tran-Truong, and Son Ha Xuan. 2026. When Audit Quality Fails to Predict Downstream Utility: Synthetic-Data Selection for Low-Resource Classification. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 25027–25045, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
When Audit Quality Fails to Predict Downstream Utility: Synthetic-Data Selection for Low-Resource Classification (Le et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.1184.pdf