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Knowledge Base Scope Matters: A Comparative Study of Retrieval-Augmented Generation in Academic Library Collection Development

Zhang K, Jiang B, Guo Y, Liu X

2026

Abstract

Abstract As academic libraries explore large language models (LLMs) for collection development, the impact of knowledge base scope in Retrieval-Augmented Generation (RAG) remains underexamined. This study compares three configurations—NoRAG baseline, a broad geoscience knowledge base (RAG-Geo), and a specialized remote sensing subfield knowledge base (RAG-RS)—using 525 monographs in astronomy and geosciences (CLC class P). Results show that RAG-based configurations reduce score standard deviation from 21.36 (NoRAG) to 17.68 (RAG-Geo) and 18.67 (RAG-RS), while median scores drop from 75 to 70 and 65, respectively. Citation markers appear in 77.1% (RAG-Geo) and 73.5% (RAG-RS) of scoring rationales at higher score levels, indicating increased evidence grounding. The specialized knowledge base (RAG-RS) leads to score reductions of 9–11 points in subfields closely related to its focus (surveying, geophysics, atmospheric sciences), whereas the broad knowledge base (RAG-Geo) yields smaller reductions of 5–7 points and more uniform adjustments across disciplines. These findings demonstrate that knowledge base scope actively modulates RAG evaluation patterns. The study provides empirical guidance for academic libraries in selecting knowledge bases and introduces a quantitative proxy—citation proportion—for evidence grounding.

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