做RAG系统优化的团队终于有了一个能精确控制风险与检索成本的校准工具——BalanceRAG 用联合阈值替代逐级保守校准，在保证准确率的同时减少不必要的检索调用，建议做问答系统的开发者点开看看。
BalanceRAG 提出了一种针对级联检索增强生成（RAG）系统的联合风险校准方法。传统级联RAG会先尝试仅用大模型回答，不确定时再启用RAG，但各阶段独立校准可能过于保守。BalanceRAG 将阈值对视为二维网格上的操作点，通过序贯图形测试识别安全操作点，实现系统级错误率控制。该方法支持多风险校准，能在保证风险水平的同时保留更多样本，减少不必要的检索调用。在多个开放域问答基准测试中，BalanceRAG 在满足预设风险水平的前提下，提高了覆盖率和正确样本接受数。
BalanceRAG: Joint Risk Calibration for Cascaded Retrieval-Augmented Generation
Large language models (LLMs) can enhance factuality via retrieval-augmented generation (RAG), but applying RAG to every query is unnecessary when the model-only answer is reliable. This motivates cascaded RAG: each query is first handled by an LLM-only branch, escalated to a RAG fallback only if the primary branch is uncertain, and abstained from when neither branch is sufficiently trustworthy. However, calibrating such cascades stage by stage may be conservative, since the final utility depends on joint uncertainty thresholding of LLM-only and RAG. In this work, we develop BalanceRAG to certify threshold pairs at a target risk level. Given uncertainty scores from the two branches, BalanceRAG frames each threshold pair as an operating point on a two-dimensional lattice and identifies safe operating points using sequential graphical testing. This enables risk-adaptive threshold calibration, controlling the system-level error rate among accepted points, while retaining more examples. Furthermore, BalanceRAG extends to multi-risk calibration, allowing retrieval usage to be bounded together with the selection-conditioned risk. Experiments on three open-domain question answering (QA) benchmarks across multiple LLM backbones demonstrate that BalanceRAG meets prescribed risk levels, preserves higher coverage and more accepted correct examples, and reduces unnecessary retrieval calls compared with always-on RAG.