Beyond Relevance: On the Relationship Between Retrieval and RAG Information Coverage

The article presents a systematic study on the relationship between retrieval quality and generation effectiveness in Retrieval-Augmented Generation (RAG) systems. It analyzes 15 text and 10 multimodal retrieval stacks across various RAG pipelines using two text benchmarks (TREC NeuCLIR 2024 and TREC RAG 2024) and one multimodal benchmark (WikiVideo), revealing strong correlations between retrieval metrics and the information coverage of generated responses. This research underscores the importance of aligning retrieval objectives with generation goals, suggesting that retrieval metrics can serve as reliable indicators for RAG performance, which is crucial for practitioners optimizing these systems.