QUORUM: QUality-Optimized Routing Using Multiple annotators

Antonio Purificato, Maria Sofia Bucarelli, Andrea Bacciu, Amin Mantrach, Fabrizio Silvestri


Abstract
Data annotation remains a central bottleneck in natural language processing, requiring human effort to obtain high-quality labels at scale. While Large Language Models (LLMs) offer a fast and cost-effective alternative, their reliability is highly instance-dependent: they perform well on simple inputs but often fail on examples requiring nuanced reasoning or contextual understanding. In this work, we address this challenge with QUORUM (QUality-Optimized Routing Using Multiple annotators), a budget-aware routing framework that dynamically assigns each instance to human or LLM annotators under a fixed annotation budget. Unlike prior approaches relying on model confidence or uncertainty estimates, QUORUM leverages feature-based signals to estimate instance difficulty and supports multiple annotations per instance, combining them through agreement-based rewards to improve reliability. We evaluate QUORUM across diverse closed- and open-ended annotation tasks in English and multilingual settings, and QUORUM improves annotation quality by up to 34.4% while reducing costs by 8.8% over competing methods. Code can be found at https://github.com/amazon-science/QUORUM.
Anthology ID:
2026.emnlp-main.1172
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:
26873–26890
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1172/
DOI:
Bibkey:
Cite (ACL):
Antonio Purificato, Maria Sofia Bucarelli, Andrea Bacciu, Amin Mantrach, and Fabrizio Silvestri. 2026. QUORUM: QUality-Optimized Routing Using Multiple annotators. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 26873–26890, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
QUORUM: QUality-Optimized Routing Using Multiple annotators (Purificato et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1172.pdf