Same Question, Different Source, Different Answer: Auditing Source-Dependence in Medical Multi-Source RAG
On the map: Retrieval-augmented generation → Medical and biomedical RAG
Abstract (arXiv)
A retrieval-augmented generation (RAG) system deployed over a multi-author institutional corpus can give a different answer to the same question depending on which source it retrieves -- a failure mode the dominant single-gold-answer paradigm cannot diagnose. We argue that source-dependence is a missing axis of NLP evaluation, and that auditing it means shifting the unit of evaluation from answer correctness to the inter-source relationship. We make this concrete in transplant patient education, where institutional sources demonstrably disagree, releasing three artefacts: TransplantQA, a benchmark of real patient questions, each answered by grounding generation in multiple institutional handbooks as candidate sources; HERO-QA, a hierarchical retrieval strategy that grounds and audits each answer; and a structured-output judge that scores inter-source relationships on a validated 5-label taxonomy. At scale, better retrieval reveals far more disagreement than prior estimates suggested -- understating its prevalence, not its intensity. The framework is domain-agnostic and transfers to legal and educational RAG: measuring source-dependence is a responsibility for deployed multi-source NLP generally.
Key facts. No citing papers in the map yet (data through 14 Oct 2026). Placed in Medical and biomedical RAG, one of 15 directions in Retrieval-augmented generation. Builds on 13 of its 23 references that are in the map. First posted on arXiv 27 May 2026.
Builds on
13 of 23 references.
References · 13
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- 2023G-Eval: NLG Evaluation using GPT-4 with Better Human Alignmentcited by 2,276
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- 2020What Disease does this Patient Have? A Large-scale Open Domain Question Answering Dataset from Medical Examscited by 1,356
- 2019PubMedQA: A Dataset for Biomedical Research Question Answeringcited by 1,288
- 2023FActScore: Fine-grained Atomic Evaluation of Factual Precision in Long Form Text Generationcited by 1,282
- 2023C-Pack: Packed Resources For General Chinese Embeddingscited by 578
- 2024Prometheus 2: An Open Source Language Model Specialized in Evaluating Other Language Modelscited by 446
- 2023RAGTruth: A Hallucination Corpus for Developing Trustworthy Retrieval-Augmented Language Modelscited by 283
- 2020MedDialog: Two Large-scale Medical Dialogue Datasetscited by 161
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- 2026When Documents Disagree: Measuring Institutional Variation in Transplant Guidance with Retrieval-Augmented Language Models
- 2025Contradictions in Context: Challenges for Retrieval-Augmented Generation in Healthcare
- 2026When Retrieval Doesn't Help: A Large-Scale Study of Biomedical RAG
- 2025M-Eval: A Heterogeneity-Based Framework for Multi-evidence Validation in Medical RAG Systems
- 2025Rethinking Retrieval-Augmented Generation for Medicine: A Large-Scale, Systematic Expert Evaluation and Practical Insights
- 2024How well do LLMs cite relevant medical references? An evaluation framework and analyses
- 2025Evaluating the Robustness of Retrieval-Augmented Generation to Adversarial Evidence in the Health Domain
- 2024Enhancing Large Language Models with Domain-specific Retrieval Augment Generation: A Case Study on Long-form Consumer Health Question Answering in Ophthalmology