用注意力机制提升监督学习的个性化预测能力
Supervised learning pays attention
- 基于注意力加权训练数据,为每个测试点构建局部模型
- 在真实与模拟数据上均提升预测性能,且保持可解释性
- 适合需要个性化建模与透明决策的场景,如医疗、金融
通过注意力机制实现上下文学习,使大型神经网络能根据上下文选择性关注相关样本以做出特定预测。本文将该思想应用于监督学习任务,如套索回归和梯度提升,处理表格数据。目标是(1)为每个预测点灵活拟合个性化模型;(2)保持模型简洁与可解释性。方法通过对训练数据按注意力权重进行加权,为每个测试观测值构建局部模型,注意力是一种有监督的相似性度量,强调对结果具有预测性的特征及其交互作用。该加权方式可数据驱动地适应异质数据,无需预先指定聚类或相似性。此外,本方法具备独特可解释性:可识别每个测试点中最具预测力的特征及最相关的训练样本。我们还展示了其在时间序列和空间数据中的应用,并提出一种基于注意力加权残差修正的方法,用于将预训练树模型适应分布偏移。在真实与模拟数据集上,注意力加权显著提升预测性能,同时保留可解释性;理论表明,在具有已知子群结构的混合模型生成过程中,注意力加权线性模型的均方误差低于标准线性模型。
原文摘要 · Abstract (English)
In-context learning with attention enables large neural networks to make context-specific predictions by selectively focusing on relevant examples. Here, we adapt this idea to supervised learning procedures such as lasso regression and gradient boosting, for tabular data. Our goals are to (1) flexibly fit personalized models for each prediction point and (2) retain model simplicity and interpretability. Our method fits a local model for each test observation by weighting the training data according to attention, a supervised similarity measure that emphasizes features and interactions that are predictive of the outcome. Attention weighting allows the method to adapt to heterogeneous data in a data-driven way, without requiring cluster or similarity pre-specification. Further, our approach is uniquely interpretable: for each test observation, we identify which features are most predictive and which training observations are most relevant. We then show how to use attention weighting for time series and spatial data, and we present a method for adapting pretrained tree-based models to distributional shift using attention-weighted residual corrections. Across real and simulated datasets, attention weighting improves predictive performance while preserving interpretability, and theory shows that attention-weighting linear models attain lower mean squared error than the standard linear model under mixture-of-models data-generating processes with known subgroup structure.
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