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Causal Evidence Extraction and Triangulation in Crisis Reports using Large Language Models: A ReliefWeb-based Study

Paper · 2026 · Yuanjun Zhang and Mourad Oussalah

Summary

Humanitarian situation reports are long and cover many topics at once, so it is hard to pull out comparable evidence about which interventions help and in which contexts. The authors build a two-stage LLM pipeline for ReliefWeb reports (2000–2024) retrieved with the query "cash assistance". The first stage is query-conditioned: it keeps only interventions of the requested class and collects outcome mentions with supporting snippets. The second stage uses those snippets to label each pair's direction (increase, decrease, no change) and evidence strength. This design counters the noise that recall-oriented keyword retrieval brings in. On an expert-annotated benchmark, Qwen-Plus gave the best closed-source result, and a LoRA-distilled Llama-3.1-8B-Instruct did better still. The authors also introduce context-preserving triangulation, which aggregates evidence within disaster×source cells rather than pooling raw counts and summarises cross-context agreement as a Level-of-Evidence (LoE) score. Applied to cash assistance, it shows consistently positive effects on food-related outcomes. The work matters because it offers auditable, scalable evidence synthesis for humanitarian decision support.

Key points

  • Corpus: 8,029 English ReliefWeb reports covering 4 disaster types (flood, drought, epidemic, earthquake) and 5 source types. The evaluation set has 100 expert-annotated reports with 220 relations, matched using BERTScore at a 0.8 threshold.
  • Query conditioning sharply reduces over-extraction. For Qwen-Plus, the average drops from 13.76 to 2.79 relations per document, against a ground truth of 2.20.
  • Qwen-Plus with two-step QC + SG reached 90.73% weighted F1 and had the best cost-efficiency of the three API models; the other two were GPT-4o-mini and DeepSeek-V3.
  • Llama-3.1-8B-Instruct, fine-tuned with LoRA on the teacher's outputs (one adapter per stage), improved from 75.12% to 94.15% weighted F1.
  • Triangulation used 19,568 extracted records and kept 19 of 20 disaster×source cells. For food outcomes it gave P_P = 0.91 and LoE = 0.865, with the cumulative LoE peaking in 2017 at 0.929.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

Also on the byline: Lappeenranta-Lahti University of Technology.

 Fields, topics and concepts

Cite

Cite as Yuanjun Zhang and Mourad Oussalah. 2026. Causal Evidence Extraction and Triangulation in Crisis Reports using Large Language Models: A ReliefWeb-based Study. Findings of the Association for Computational Linguistics: ACL 2026.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.findings-acl.1626

@inproceedings{zhang2026causal,
  title = {{Causal Evidence Extraction and Triangulation in Crisis Reports using Large Language Models: A ReliefWeb-based Study}},
  author = {Yuanjun Zhang and Mourad Oussalah},
  booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
  year = {2026},
  doi = {10.18653/v1/2026.findings-acl.1626},
  url = {https://doi.org/10.18653/v1/2026.findings-acl.1626}
}

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