提升贝叶斯辅助置信预测的鲁棒性,让预测区间在分布偏移时更紧凑可靠。
Robust Bayes-Assisted Conformal Prediction
- 设计两种鲁棒非相似度评分:重尾先验与经验贝叶斯收缩
- 在分布偏移时预测区间宽度显著缩小,性能优于传统方法
- 适合数据分布不一致但测试数据可交换的场景,如迁移学习
贝叶斯辅助置信预测结合了贝叶斯建模的优势与严格、无需分布假设的频率覆盖保证。尽管当贝叶斯工作模型(BWM)误设时仍能保持置信有效性,但若先验与观测数据不匹配,预测集大小可能严重恶化。本文提出RoBAS(鲁棒贝叶斯辅助收缩)框架,构建稳健的非相似度评分,包含两种实现:基于重尾先验的版本和闭式经验贝叶斯收缩评分。所提评分能自适应先验信息质量:当先验可靠时高效利用其信息生成紧凑预测集;当先验弱或错误时则退化为稳健的无信息基准——距离平均值(DTA)评分。我们在表格与图像回归任务上评估该方法,训练分布可能与校准及测试分布不同,而校准与测试数据仍满足可交换性。结果表明,在无分布偏移时性能与常用评分相当,而在分布偏移情况下显著缩小预测区间宽度。
原文摘要 · Abstract (English)
Bayes-assisted conformal prediction combines the strengths of Bayesian modelling with exact, distribution-free frequentist coverage guarantees. Although conformal validity is preserved even when the Bayesian working model (BWM) is misspecified, the size of the resulting prediction sets can degrade substantially when the prior is poorly aligned with the observed data. We address this limitation by introducing RoBAS (Robust Bayes-Assisted Shrinkage): a Bayes-assisted framework for constructing robust nonconformity scores, with two instantiations: one induced by a heavy-tailed BWM, and a closed-form empirical Bayes shrinkage score. The resulting scores adapt to the quality of the working information encoded in the prior: when this information is reliable, they exploit it to produce efficient prediction sets; when it is weak or inaccurate, they revert to the Distance-To-Average (DTA) score, a robust non-informative baseline. We evaluate the proposed scores on tabular and image regression tasks where the training distribution may differ from the calibration and test distributions, while the calibration and test data themselves remain exchangeable. We find that they are competitive with widely used scores in the absence of such shift, while substantially reducing interval widths in shifted settings.
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