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Evaluating Retrieval-Augmented Generation Architectures for Single and Multi-Hop Question Answering

Cherevichnik, Stepan

Epubl LTU, 2025

Abstract

Retrieval-Augmented Generation has emerged as a powerful technique for improving the factual accuracy and contextual relevance of large language model outputs. This thesis examines how di!erent RAG pipeline configurations influence performance in general applications, and further evaluates their e!ectiveness in a realistic, domain- specific setting: a university information assistant. A synthetic multi-hop QA dataset was constructed by scraping and semantically linking documents from the Lule˚a University of Technology (LTU) website. Synthetic personas were used to guide the generation of diverse and realistic student-focused queries. Mul- tiple RAG pipeline variants were implemented, di!ering in their retrieval strategies and augmentation techniques, including dense, hybrid, query expansion, and hypothetical document embedding (HyDE) approaches. Each pipeline was evaluated on both single-hop and multi-hop questions using a cus- tom framework that measured document retrieval accuracy (MRR), answer faithfulness, context relevance, and semantic similarity to reference answers. Results show that retrieval quality plays a central role in downstream generation per- formance, particularly for multi-hop queries. The findings o!er practical insights into e!ective RAG design for specialized QA applications, and the dataset and pipeline design can serve as a foundation for future research in academic or institutional information systems.

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