We study the domain adaptation problem with label shift in this work. Under the label shift context, the marginal distribution of the label varies across the training and testing datasets, while the conditional distribution of features given the label is the same. Traditional label shift adaptation methods either suffer from large estimation errors or require cumbersome post-prediction calibrations. To address these issues, we first propose a moment-matching framework for adapting the label shift based on the geometry of the influence function. Under such a framework, we propose a novel method named \underline{E}fficient \underline{L}abel \underline{S}hift \underline{A}daptation (ELSA), in which the adaptation weights can be estimated by solving linear systems. Theoretically, the ELSA estimator is $\sqrt{n}$-consistent ($n$ is the sample size of the source data) and asymptotically normal. Empirically, we show that ELSA can achieve state-of-the-art estimation performances without post-prediction calibrations, thus, gaining computational efficiency.

本文探讨如何解决标签偏移的域自适应问题，提出了基于影响函数几何的时刻匹配框架，讨论了一种名为ELSA的解决方案，并通过大量实验证明该方法在无需繁琐的后验校准的情况下，能达到与最先进方法一样的性能并获得计算效率的提升。

ELSA: 通过半参数模型视角实现有效标签偏移适应