提出深度非参数条件独立检验,用于图像等高维数据的因果分析。
Deep Nonparametric Conditional Independence Tests for Images
- 用嵌入映射提取图像特征,结合非参数检验判断条件独立性。
- 在英国生物银行数据中验证了多个性格神经科学研究的零结果。
- 提供R包支持,适合做医学影像因果推断的研究者使用。
条件独立性检验(CITs)用于检测随机变量间的条件依赖关系。现有CITs难以应用于图像等复杂高维变量,本文提出深度非参数条件独立检验(DNCITs),将特征嵌入映射与适用于特征表示的非参数检验相结合。嵌入映射通过推导其参数估计器的一般性质,确保DNCIT的有效性,涵盖通过(条件)无监督或迁移学习获得的映射。非参数检验则根据特征表示特性进行选择与适配。通过模拟实验,评估了不同嵌入映射与非参数检验在不同混淆因子维度和关系下的表现。在英国生物银行(UKB)健康个体的脑部MRI与行为特质数据上应用DNCITs,确认了多项存在争议的性格神经科学研究的零结果,且基于更大样本和更强检验能力。此外,在混淆因子控制研究中,利用DNCITs检验脑部影像与混淆因子集之间的充分控制,发现相比现有最佳方法,可实现更低的混淆因子维度。最后,本文提供了实现DNCITs的R包。
原文摘要 · Abstract (English)
Conditional independence tests (CITs) test for conditional dependence between random variables. As existing CITs are limited in their applicability to complex, high-dimensional variables such as images, we introduce deep nonparametric CITs (DNCITs). The DNCITs combine embedding maps, which extract feature representations of high-dimensional variables, with nonparametric CITs applicable to these feature representations. For the embedding maps, we derive general properties on their parameter estimators to obtain valid DNCITs and show that these properties include embedding maps learned through (conditional) unsupervised or transfer learning. For the nonparametric CITs, appropriate tests are selected and adapted to be applicable to feature representations. Through simulations, we investigate the performance of the DNCITs for different embedding maps and nonparametric CITs under varying confounder dimensions and confounder relationships. We apply the DNCITs to brain MRI scans and behavioral traits, given confounders, of healthy individuals from the UK Biobank (UKB), confirming null results from a number of ambiguous personality neuroscience studies with a larger data set and with our more powerful tests. In addition, in a confounder control study, we apply the DNCITs to brain MRI scans and a confounder set to test for sufficient confounder control, leading to a potential reduction in the confounder dimension under improved confounder control compared to existing state-of-the-art confounder control studies for the UKB. Finally, we provide an R package implementing the DNCITs.
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