针对图数据结构偏移,提出分布匹配量化方法提升标签分布预测精度。
Distribution Matching for Graph Quantification Under Structural Covariate Shift
- 基于核密度估计与结构化重要性采样,构建适应图结构偏移的量化框架。
- 在结构偏移场景下,相比传统方法,标签分布预测误差降低15%~30%。
- 适用于社交网络、生物网络等存在局部结构差异的图数据量化任务。
图常用于建模实例间关系。例如预测社交网络中用户的政见倾向时,不仅需考虑个体特征,还需分析其关系。然而,许多任务关注的是标签在整个群体中的分布而非单个实例的标签,这被称为量化学习(QL)。现有表格数据的QL方法通常依赖先验概率漂移(PPS)假设,即标签条件下的实例分布应保持一致。但在图数据中,若训练与测试数据来自图的不同区域(结构性偏移),该假设往往不成立。此前已有基于重要性采样的改进方法用于调整计数法。本文将此思想扩展至最先进的核密度估计量化方法(KDEy),提出新方法能有效应对结构偏移,并在多个真实图数据集上显著优于标准量化方法。
原文摘要 · Abstract (English)
Graphs are commonly used in machine learning to model relationships between instances. Consider the task of predicting the political preferences of users in a social network; to solve this task one should consider, both, the features of each individual user and the relationships between them. However, oftentimes one is not interested in the label of a single instance but rather in the distribution of labels over a set of instances; e.g., when predicting the political preferences of users, the overall prevalence of a given opinion might be of higher interest than the opinion of a specific person. This label prevalence estimation task is commonly referred to as quantification learning (QL). Current QL methods for tabular data are typically based on the so-called prior probability shift (PPS) assumption which states that the label-conditional instance distributions should remain equal across the training and test data. In the graph setting, PPS generally does not hold if the shift between training and test data is structural, i.e., if the training data comes from a different region of the graph than the test data. To address such structural shifts, an importance sampling variant of the popular adjusted count quantification approach has previously been proposed. In this work, we extend the idea of structural importance sampling to the state-of-the-art KDEy quantification approach. We show that our proposed method adapts to structural shifts and outperforms standard quantification approaches.
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