arXiv:2605.17160cs.LGcs.AI2026-05

量化压缩可能让可操作建议失效,本文提出新方法保障决策可纠正性。

When Bits Break Recourse: Counterfactual-Faithful Quantization

论文配图:When Bits Break Recourse: Counterfactual-Faithful Quantization
图 1 · 摘自论文原文
  • 提出量化后反事实敏感度框架,评估压缩对可操作建议的影响
  • 引入有效性下降率与反事实成本差距两个指标,量化建议失效程度
  • 设计量化感知训练方法,使低精度模型仍能保持有效建议

模型量化广泛用于降低内存、延迟和部署成本,通常以预测准确率是否保留为评判标准。但在提供算法可操作建议的决策系统中,仅保留准确率并不足够:一个在全精度模型下能改变决策的小幅度可行动操作,在量化后可能失效或需大幅调整。本文研究此部署不一致问题,提出量化下的反事实敏感性框架,用于衡量压缩如何改变可操作行为。我们定义两个指标:有效性下降率(VD),衡量全精度模型下可操作建议在量化后无法达成目标结果的比例;反事实可操作差距(CRG),衡量量化模型下最小可操作成本的增加量。为缓解此问题,我们提出反事实忠实量化(CFQ),一种量化感知训练方法,联合学习量化参数与混合精度比特分配,同时在教师生成的可操作点上保持目标预测。CFQ兼容标准的LSQ/PACT型量化器和混合精度策略,也可作为训练后量化的免训练校准方案。在Adult、German Credit和COMPAS数据集上的实验表明,标准量化训练与混合精度基线可在保持准确率的同时显著恶化可操作稳定性。在匹配准确率和比特预算下,CFQ始终降低VD与CRG;例如在Adult数据集上,将VD/CRG从0.121/0.162降至0.061/0.071。

原文摘要 · Abstract (English)

Model quantization is widely used to reduce memory, latency, and deployment cost, and is typically judged by whether predictive accuracy is preserved. In decision systems that provide algorithmic recourse, however, accuracy preservation is not sufficient: a small actionable change that flips the decision of a full-precision model may fail after quantization, or require a substantially larger intervention. This paper studies this deployment mismatch and introduces counterfactual sensitivity under quantization, a framework for measuring how compression changes recourse behavior. We propose two metrics: Validity Drop (VD), which measures the fraction of full-precision recourse actions that no longer achieve the target outcome after quantization, and Counterfactual Recourse Gap (CRG), which measures the increase in minimal recourse cost under the quantized model. To mitigate this failure mode, we introduce Counterfactual-Faithful Quantization (CFQ), a quantization-aware training method that jointly learns quantizer parameters and mixed-precision bit allocation while preserving the target prediction at teacher-generated recourse points. CFQ is compatible with standard LSQ/PACT-style quantizers and mixed-precision policies, and can also be instantiated as a training-free calibration procedure for post-training quantization. Experiments on Adult, German Credit, and COMPAS show that standard QAT and mixed-precision baselines can preserve accuracy while substantially degrading recourse stability. At matched accuracy and bit budget, CFQ consistently reduces VD and CRG; for example, on Adult, CFQ reduces VD/CRG from $0.121/0.162$ for an accuracy-centric mixed-precision baseline to $0.061/0.071$.

模型量化可解释性公平性反事实

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