提出新损失函数Tube Loss,可精准生成预测区间并自动优化宽窄与覆盖率。
Tube Loss: A Novel Approach for Prediction Interval Estimation
- 用新损失函数同时优化预测区间的上下界,支持灵活调节位置。
- 在多种数据集上实现更高覆盖率与更窄平均宽度的预测区间。
- 兼容梯度下降,适合深度模型,适用于风速等偏态分布场景。
本文提出一种新型损失函数——Tube Loss,用于回归任务中同时估计预测区间(PI)的上下界。基于该损失函数的经验风险最小化所获得的预测区间,在以下方面优于现有方法:第一,渐近地达到预设置信水平 t ∈ (0,1),理论证明成立;第二,通过调整一个参数可上下移动区间,从而捕获响应变量概率分布更密集的区域,有效缩小区间宽度,对条件分布偏斜的情况尤为有益;第三,可通过单一优化问题在覆盖率与平均宽度间进行权衡,并通过再校准进一步压缩平均宽度。与部分现有方法不同,该方法支持使用梯度下降进行优化。大量实验表明,无论是核机器还是神经网络,基于Tube Loss的预测方法均表现优异。此外,在多个基准数据集和风电数据集上,其深度概率预测模型性能超越现有技术。最后,我们在合规预测框架下实证验证了Tube Loss的优势。代码已开源:https://github.com/ltpritamanand/Tube_loss。
原文摘要 · Abstract (English)
This paper proposes a novel loss function, called 'Tube Loss', for simultaneous estimation of bounds of a Prediction Interval (PI) in the regression setup. The PIs obtained by minimizing the empirical risk based on the Tube Loss are shown to be of better quality than the PIs obtained by the existing methods in the following sense. First, it yields intervals that attain the prespecified confidence level t $\in$ (0,1) asymptotically. A theoretical proof of this fact is given. Secondly, the user is allowed to move the interval up or down by controlling the value of a parameter. This helps the user to choose a PI capturing denser regions of the probability distribution of the response variable inside the interval, and thus, sharpening its width. This is shown to be especially useful when the conditional distribution of the response variable is skewed. Further, the Tube Loss based PI estimation method can trade-off between the coverage and the average width by solving a single optimization problem. It enables further reduction of the average width of PI through re-calibration. Also, unlike a few existing PI estimation methods the gradient descent (GD) method can be used for minimization of empirical risk. Through extensive experiments, we demonstrate the effectiveness of Tube Loss-based PI estimation in both kernel machines and neural networks. Additionally, we show that Tube Loss-based deep probabilistic forecasting models achieve superior performance compared to existing probabilistic forecasting techniques across several benchmark and wind datasets. Finally, we empirically validate the advantages of the Tube loss approach within the conformal prediction framework. Codes are available at https://github.com/ltpritamanand/Tube$\_$loss.
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