Dev.to
7/18/2026

The original title is: "Retrieval-Augmented Self-Recall — Part 4: Benchmarking Retrieval *and* Honesty"
Original: Retrieval-Augmented Self-Recall — Part 4: Benchmarking Retrieval *and* Honesty
Short summary
The author builds a custom RAG evaluation harness that scores both ranking quality (MRR, nDCG) and honesty (False-Confident Rate) — the fraction of unanswerable queries where the system fails to abstain. Ablation results show hybrid fusion and cross-encoder reranking provide large gains on weak embedders but zero benefit when a strong embedder already achieves perfect ranking. The key engineering takeaway: measure before stacking pipeline stages, and benchmark abstention behavior alongside retrieval accuracy.
- •Custom harness evaluates both ranking quality and abstention honesty (FCR) — a metric almost nobody reports
- •Hybrid + rerank buys the most on weak embedders; redundant on strong embedders with easy corpora
- •All benchmarks run against live pgvector in CI with 49 integration tests, ensuring reproducibility
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