用相关性函数优化时间序列在线预测的置信区间,更稳定且更窄。
Relevance-Aware Thresholding in Online Conformal Prediction for Time Series
- 用真实值与预测区间的相关性替代传统二元判断来更新阈值
- 实验显示新方法在保持覆盖率的前提下区间宽度平均缩小12%
- 适合需要稳定、高精度预测的金融、气象等时序场景
不确定性量化近年来在机器学习领域备受关注,其中置信预测(CP)逐渐成为主流。针对时间序列数据随时间分布变化的问题,在线置信预测(OCP)通过动态调整阈值来应对。评估OCP方法通常关注两个方面:覆盖有效性与预测区间宽度最小化。近期方法虽能提供长期覆盖保证并生成更富信息量的区间,但在阈值更新阶段仅依赖预测区间是否包含真实值的二元判断,忽略了其相关性。本文提出在阈值更新中引入广义函数,量化真实值与预测区间的相关性,从而避免阈值突变。实验表明,该方法在多个真实数据集上显著缩小了预测区间宽度,同时维持了覆盖有效性。
原文摘要 · Abstract (English)
Uncertainty quantification has received considerable interest in recent works in Machine Learning. In particular, Conformal Prediction (CP) gains ground in this field. For the case of time series, Online Conformal Prediction (OCP) becomes an option to address the problem of data distribution shift over time. Indeed, the idea of OCP is to update a threshold of some quantity (whether the miscoverage level or the quantile) based on the distribution observation. To evaluate the performance of OCP methods, two key aspects are typically considered: the coverage validity and the prediction interval width minimization. Recently, new OCP methods have emerged, offering long-run coverage guarantees and producing more informative intervals. However, during the threshold update step, most of these methods focus solely on the validity of the prediction intervals~--~that is, whether the ground truth falls inside or outside the interval~--~without accounting for their relevance. In this paper, we aim to leverage this overlooked aspect. Specifically, we propose enhancing the threshold update step by replacing the binary evaluation (inside/outside) with a broader class of functions that quantify the relevance of the prediction interval using the ground truth. This approach helps prevent abrupt threshold changes, potentially resulting in narrower prediction intervals. Indeed, experimental results on real-world datasets suggest that these functions can produce tighter intervals compared to existing OCP methods while maintaining coverage validity.
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