提出误差量化共形推断,提升时间序列预测置信集精度与稳定性。
Error-quantified Conformal Inference for Time Series
- 通过平滑分位数损失函数,引入连续自适应反馈机制。
- 在任意依赖和分布漂移下实现长期覆盖率保证,置信集更紧凑。
- 适合需要可靠不确定性评估的时间序列建模场景。
时间序列预测中的不确定性量化因时序依赖和分布漂移而困难。共形推断通过预测集为机器学习模型提供灵活的不确定性评估。近期在线共形推断方法通过在线梯度下降更新预测集阈值,但仅利用误覆盖指示器中的非符合性分数信息,忽略误差量化(即非符合性分数与当前阈值的距离)。为准确捕捉误覆盖误差动态,我们提出误差量化共形推断(ECI),通过平滑分位数损失函数实现连续自适应反馈,而非现有方法的二元反馈。在任意依赖和分布漂移条件下,建立了ECI的长期覆盖率保证。大量实验表明,ECI能实现有效的误覆盖控制,并生成比基线更紧致的预测集。
原文摘要 · Abstract (English)
Uncertainty quantification in time series prediction is challenging due to the temporal dependence and distribution shift on sequential data. Conformal inference provides a pivotal and flexible instrument for assessing the uncertainty of machine learning models through prediction sets. Recently, a series of online conformal inference methods updated thresholds of prediction sets by performing online gradient descent on a sequence of quantile loss functions. A drawback of such methods is that they only use the information of revealed non-conformity scores via miscoverage indicators but ignore error quantification, namely the distance between the non-conformity score and the current threshold. To accurately leverage the dynamic of miscoverage error, we propose \textit{Error-quantified Conformal Inference} (ECI) by smoothing the quantile loss function. ECI introduces a continuous and adaptive feedback scale with the miscoverage error, rather than simple binary feedback in existing methods. We establish a long-term coverage guarantee for ECI under arbitrary dependence and distribution shift. The extensive experimental results show that ECI can achieve valid miscoverage control and output tighter prediction sets than other baselines.
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