Who Gets Annotated? Impact-Aware Active Learning for Robust Humanitarian Text Classification

Divyajot Singh


Abstract
Humanitarian organizations must adapt text classifiers to new crises with small annotation budgets, yet conventional active learning optimizes model uncertainty without representing operational criticality or coverage across disaster events. We study an impact-aware batch acquisition policy that combines expected criticality, uncertainty, representation-space diversity, and event balance. Our evaluation crosses three recent open embedding backbones, three representation treatments, five acquisition strategies, five paired seeds, and total budgets of 50–500 labels. We separate exploratory development, event-held-out robustness on HumAID, and an untouched cross-dataset confirmation on CrisisMMD. On CrisisMMD, impact-aware selection with a conservative residual adapter improves Qwen’s area under the learning curve over random sampling by 0.089 for critical-category recall, 0.026 for macro-F1, and 0.032 for worst-event macro-F1. It raises the critical share of the 500-example labeled set from 3.4% to 26.8% and allocates annotations more evenly across events. Critical-recall gains also hold for Harrier and EmbeddingGemma on CrisisMMD and transfer to unseen HumAID events for Harrier, but not Qwen, exposing a consequential representation–dataset interaction. No configuration dominates every operational objective. Finally, 512-dimensional Qwen halves embedding storage while remaining within 0.009 AULC of its full representation across primary outcomes and both test settings. These results support impact-aware acquisition as a useful, but not always-on, policy and motivate reporting Pareto trade-offs rather than a single aggregate score.
Anthology ID:
2026.nlp4pi-1.44
Volume:
Proceedings of the Fifth Workshop on NLP for Positive Impact (NLP4PI)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Katherine Atwell, Angana Borah, Daryna Dementieva, Elisa Kreiss, Neema Kotonya, Jiarui Liu, Liz Olson, Ruyuan Wan, Jieyu Zhao
Venues:
NLP4PI | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
605–614
Language:
URL:
https://aclanthology.org/2026.nlp4pi-1.44/
DOI:
Bibkey:
Cite (ACL):
Divyajot Singh. 2026. Who Gets Annotated? Impact-Aware Active Learning for Robust Humanitarian Text Classification. In Proceedings of the Fifth Workshop on NLP for Positive Impact (NLP4PI), pages 605–614, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Who Gets Annotated? Impact-Aware Active Learning for Robust Humanitarian Text Classification (Singh, NLP4PI 2026)
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PDF:
https://aclanthology.org/2026.nlp4pi-1.44.pdf