Generalization error bounds from learning theory provide statistical guarantees on how well an algorithm will perform on previously unseen data. In this paper, we characterize the impacts of data non-IIDness due to censored feedback (a.k.a. selective labeling bias) on such bounds. We first derive an extension of the well-known Dvoretzky-Kiefer-Wolfowitz (DKW) inequality, which characterizes the gap between empirical and theoretical CDFs given IID data, to problems with non-IID data due to censored feedback. We then use this CDF error bound to provide a bound on the generalization error guarantees of a classifier trained on such non-IID data. We show that existing generalization error bounds (which do not account for censored feedback) fail to correctly capture the model's generalization guarantees, verifying the need for our bounds. We further analyze the effectiveness of (pure and bounded) exploration techniques, proposed by recent literature as a way to alleviate censored feedback, on improving our error bounds. Together, our findings illustrate how a decision maker should account for the trade-off between strengthening the generalization guarantees of an algorithm and the costs incurred in data collection when future data availability is limited by censored feedback.
翻译:学习理论中的泛化误差界提供了算法在未见数据上表现如何的统计保证。本文刻画了由删失反馈(亦称选择性标签偏差)导致的数据非独立同分布性对这些界的影响。我们首先将经典的Dvoretzky-Kiefer-Wolfowitz不等式(描述独立同分布数据下经验累积分布函数与理论累积分布函数之间的差距)推广至由删失反馈导致的非独立同分布数据问题中。进而利用该累积分布函数误差界,给出在此类非独立同分布数据上训练的分类器的泛化误差保证界。研究表明,现有未考虑删失反馈的泛化误差界无法正确捕捉模型的泛化保证,这验证了本文所提界的必要性。我们进一步分析了近期文献提出的(纯探索与有界探索)探索技术——作为缓解删失反馈的途径——对改进我们误差界的有效性。综合起来,我们的发现揭示了当未来数据可用性受删失反馈限制时,决策者应如何在强化算法泛化保证与数据收集成本之间权衡。