不依赖虚假相关性的学习预测因素涉及建立因果关系。但是,学习这样的表示非常具有挑战性。因此,我们制定了从高维数据中学习因果表示的问题,并通过合成数据研究因果恢复。这项工作引入了贝叶斯因果发现的潜在变量解码器模型BCD,并在轻度监督和无监督的环境中进行实验。我们提出了一系列合成实验,以表征因果发现的重要因素,并表明将已知的干预靶标用作标签有助于无监督的贝叶斯推断,对线性高斯添加噪声潜在结构性因果模型的结构和参数。
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Bayesian causal structure learning aims to learn a posterior distribution over directed acyclic graphs (DAGs), and the mechanisms that define the relationship between parent and child variables. By taking a Bayesian approach, it is possible to reason about the uncertainty of the causal model. The notion of modelling the uncertainty over models is particularly crucial for causal structure learning since the model could be unidentifiable when given only a finite amount of observational data. In this paper, we introduce a novel method to jointly learn the structure and mechanisms of the causal model using Variational Bayes, which we call Variational Bayes-DAG-GFlowNet (VBG). We extend the method of Bayesian causal structure learning using GFlowNets to learn not only the posterior distribution over the structure, but also the parameters of a linear-Gaussian model. Our results on simulated data suggest that VBG is competitive against several baselines in modelling the posterior over DAGs and mechanisms, while offering several advantages over existing methods, including the guarantee to sample acyclic graphs, and the flexibility to generalize to non-linear causal mechanisms.
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结构方程模型(SEM)是一种有效的框架,其原因是通过定向非循环图(DAG)表示的因果关系。最近的进步使得能够从观察数据中实现了DAG的最大似然点估计。然而,在实际场景中,可以不能准确地捕获在推断下面的底层图中的不确定性,其中真正的DAG是不可识别的并且/或观察到的数据集是有限的。我们提出了贝叶斯因果发现网(BCD网),一个变分推理框架,用于估算表征线性高斯SEM的DAG的分布。由于图形的离散和组合性质,开发一个完整的贝叶斯后面是挑战。我们通过表达变分别家庭分析可扩展VI的可扩展VI的关键设计选择,例如1)表达性变分别家庭,2)连续弛豫,使低方差随机优化和3)在潜在变量上具有合适的前置。我们提供了一系列关于实际和合成数据的实验,显示BCD网在低数据制度中的标准因果发现度量上的最大似然方法,例如结构汉明距离。
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由于数据有限和非识别性,观察性和介入数据的因果发现是具有挑战性的:在估计基本结构因果模型(SCM)时引入不确定性的因素。基于这两个因素引起的不确定性选择实验(干预措施)可以加快SCM的识别。来自有限数据的因果发现实验设计中的现有方法要么依赖于SCM的线性假设,要么仅选择干预目标。这项工作将贝叶斯因果发现的最新进展纳入了贝叶斯最佳实验设计框架中,从而使大型非线性SCM的积极因果发现同时选择了介入目标和值。我们证明了对线性和非线性SCM的合成图(ERDOS-R \'enyi,breetr cable)以及在\ emph {intiLico}单细胞基因调节网络数据集的\ emph {inyeare scms的性能。
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贝叶斯结构学习允许从数据推断贝叶斯网络结构,同时推理认识性不确定性 - 朝着实现现实世界系统的主动因果发现和设计干预的关键因素。在这项工作中,我们为贝叶斯结构学习(DIBS)提出了一般,完全可微分的框架,其在潜在概率图表表示的连续空间中运行。与现有的工作相反,DIBS对局部条件分布的形式不可知,并且允许图形结构和条件分布参数的关节后部推理。这使得我们的配方直接适用于复杂贝叶斯网络模型的后部推理,例如,具有由神经网络编码的非线性依赖性。使用DIBS,我们设计了一种高效,通用的变分推理方法,用于近似结构模型的分布。在模拟和现实世界数据的评估中,我们的方法显着优于关节后部推理的相关方法。
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在贝叶斯结构学习中,我们有兴趣从数据中推断出贝叶斯网络的定向无环图(DAG)结构。由于组合较大的样本空间,定义这种分布非常具有挑战性,并且通常需要基于MCMC的近似值。最近,已引入了一种新型的概率模型,称为生成流网络(GFLOWNETS),作为离散和复合对象(例如图形)生成建模的一般框架。在这项工作中,我们建议使用GFLOWNET作为MCMC的替代方案,以近似贝叶斯网络结构的后验分布,给定观测数据集。从该近似分布中生成样本DAG被视为一个顺序决策问题,在该问题中,该图是根据学习的过渡概率一次构造一个边缘的。通过对模拟和真实数据的评估,我们表明我们的方法称为dag-gflownet,可以准确地近似DAG,并且它可以与基于MCMC或变异推断的其他方法进行比较。
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因果推断对于跨业务参与,医疗和政策制定等领域的数据驱动决策至关重要。然而,关于因果发现的研究已经与推理方法分开发展,从而阻止了两个领域方法的直接组合。在这项工作中,我们开发了深层端到端因果推理(DECI),这是一种基于流动的非线性添加噪声模型,该模型具有观察数据,并且可以执行因果发现和推理,包括有条件的平均治疗效果(CATE) )估计。我们提供了理论上的保证,即DECI可以根据标准因果发现假设恢复地面真实因果图。受应用影响的激励,我们将该模型扩展到具有缺失值的异质,混合型数据,从而允许连续和离散的治疗决策。我们的结果表明,与因果发现的相关基线相比,DECI的竞争性能和(c)在合成数据集和因果机器学习基准测试基准的一千多个实验中,跨数据类型和缺失水平进行了估计。
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我们研究了全球优化因果关系变量的因果关系变量的问题,在该目标变量中可以进行干预措施。这个问题在许多科学领域都引起,包括生物学,运营研究和医疗保健。我们提出了因果熵优化(CEO),该框架概括了因果贝叶斯优化(CBO),以说明所有不确定性来源,包括由因果图结构引起的。首席执行官在因果效应的替代模型中以及用于通过信息理论采集函数选择干预措施的机制中纳入了因果结构的不确定性。所得算法自动交易结构学习和因果效应优化,同时自然考虑观察噪声。对于各种合成和现实世界的结构性因果模型,与CBO相比,CEO可以更快地与全局最佳达到融合,同时还可以学习图形。此外,我们的结构学习和因果优化的联合方法在顺序的结构学习优先方法上改善了。
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因果代表学习揭示了低级观察背后的潜在高级因果变量,这对于一组感兴趣的下游任务具有巨大的潜力。尽管如此,从观察到的数据中确定真正的潜在因果表示是一个巨大的挑战。在这项工作中,我们专注于确定潜在的因果变量。为此,我们分析了潜在空间中的三个固有特性,包括传递性,置换和缩放。我们表明,传递性严重阻碍了潜在因果变量的可识别性,而排列和缩放指导指导了识别潜在因果变量的方向。为了打破传递性,我们假设潜在的潜在因果关系是线性高斯模型,其中高斯噪声的权重,平均值和方差受到额外观察到的变量的调节。在这些假设下,我们从理论上表明,潜在因果变量可以识别为微不足道的置换和缩放。基于这个理论结果,我们提出了一种新型方法,称为结构性因果变异自动编码器,该方法直接学习潜在因果变量,以及从潜在因果变量到观察到的映射。关于合成和实际数据的实验结果证明了可识别的结果以及所提出的学习潜在因果变量的能力。
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Inferring causal structure poses a combinatorial search problem that typically involves evaluating structures with a score or independence test. The resulting search is costly, and designing suitable scores or tests that capture prior knowledge is difficult. In this work, we propose to amortize causal structure learning. Rather than searching over structures, we train a variational inference model to directly predict the causal structure from observational or interventional data. This allows our inference model to acquire domain-specific inductive biases for causal discovery solely from data generated by a simulator, bypassing both the hand-engineering of suitable score functions and the search over graphs. The architecture of our inference model emulates permutation invariances that are crucial for statistical efficiency in structure learning, which facilitates generalization to significantly larger problem instances than seen during training. On synthetic data and semisynthetic gene expression data, our models exhibit robust generalization capabilities when subject to substantial distribution shifts and significantly outperform existing algorithms, especially in the challenging genomics domain. Our code and models are publicly available at: https://github.com/larslorch/avici.
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In this review, we discuss approaches for learning causal structure from data, also called causal discovery. In particular, we focus on approaches for learning directed acyclic graphs (DAGs) and various generalizations which allow for some variables to be unobserved in the available data. We devote special attention to two fundamental combinatorial aspects of causal structure learning. First, we discuss the structure of the search space over causal graphs. Second, we discuss the structure of equivalence classes over causal graphs, i.e., sets of graphs which represent what can be learned from observational data alone, and how these equivalence classes can be refined by adding interventional data.
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因果表示学习是识别基本因果变量及其从高维观察(例如图像)中的关系的任务。最近的工作表明,可以从观测的时间序列中重建因果变量,假设它们之间没有瞬时因果关系。但是,在实际应用中,我们的测量或帧速率可能比许多因果效应要慢。这有效地产生了“瞬时”效果,并使以前的可识别性结果无效。为了解决这个问题,我们提出了ICITRI,这是一种因果表示学习方法,当具有已知干预目标的完美干预措施时,可以在时间序列中处理瞬时效应。 Icitris从时间观察中识别因果因素,同时使用可区分的因果发现方法来学习其因果图。在三个视频数据集的实验中,Icitris准确地识别了因果因素及其因果图。
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A vast amount of expert and domain knowledge is captured by causal structural priors, yet there has been little research on testing such priors for generalization and data synthesis purposes. We propose a novel model architecture, Causal Structural Hypothesis Testing, that can use nonparametric, structural causal knowledge and approximate a causal model's functional relationships using deep neural networks. We use these architectures for comparing structural priors, akin to hypothesis testing, using a deliberate (non-random) split of training and testing data. Extensive simulations demonstrate the effectiveness of out-of-distribution generalization error as a proxy for causal structural prior hypothesis testing and offers a statistical baseline for interpreting results. We show that the variational version of the architecture, Causal Structural Variational Hypothesis Testing can improve performance in low SNR regimes. Due to the simplicity and low parameter count of the models, practitioners can test and compare structural prior hypotheses on small dataset and use the priors with the best generalization capacity to synthesize much larger, causally-informed datasets. Finally, we validate our methods on a synthetic pendulum dataset, and show a use-case on a real-world trauma surgery ground-level falls dataset.
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Causal discovery, the inference of causal relations from data, is a core task of fundamental importance in all scientific domains, and several new machine learning methods for addressing the causal discovery problem have been proposed recently. However, existing machine learning methods for causal discovery typically require that the data used for inference is pooled and available in a centralized location. In many domains of high practical importance, such as in healthcare, data is only available at local data-generating entities (e.g. hospitals in the healthcare context), and cannot be shared across entities due to, among others, privacy and regulatory reasons. In this work, we address the problem of inferring causal structure - in the form of a directed acyclic graph (DAG) - from a distributed data set that contains both observational and interventional data in a privacy-preserving manner by exchanging updates instead of samples. To this end, we introduce a new federated framework, FED-CD, that enables the discovery of global causal structures both when the set of intervened covariates is the same across decentralized entities, and when the set of intervened covariates are potentially disjoint. We perform a comprehensive experimental evaluation on synthetic data that demonstrates that FED-CD enables effective aggregation of decentralized data for causal discovery without direct sample sharing, even when the contributing distributed data sets cover disjoint sets of interventions. Effective methods for causal discovery in distributed data sets could significantly advance scientific discovery and knowledge sharing in important settings, for instance, healthcare, in which sharing of data across local sites is difficult or prohibited.
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学习分离旨在寻找低维表示,该表示由观察数据的多个解释性和生成因素组成。变异自动编码器(VAE)的框架通常用于将独立因素从观察中解散。但是,在实际情况下,具有语义的因素不一定是独立的。取而代之的是,可能存在基本的因果结构,从而使这些因素取决于这些因素。因此,我们提出了一个名为Causalvae的新的基于VAE的框架,该框架包括一个因果层,将独立的外源性因子转化为因果内源性因素,这些因子与数据中的因果关系相关概念相对应。我们进一步分析了模型,表明从观测值中学到的拟议模型可以在一定程度上恢复真实的模型。实验是在各种数据集上进行的,包括合成和真实的基准Celeba。结果表明,因果关系学到的因果表示是可以解释的,并且其因果关系作为定向无环形图(DAG)的因果关系良好地鉴定出来。此外,我们证明了所提出的Causalvae模型能够通过因果因素的“操作”来生成反事实数据。
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State-of-the-art causal discovery methods usually assume that the observational data is complete. However, the missing data problem is pervasive in many practical scenarios such as clinical trials, economics, and biology. One straightforward way to address the missing data problem is first to impute the data using off-the-shelf imputation methods and then apply existing causal discovery methods. However, such a two-step method may suffer from suboptimality, as the imputation algorithm may introduce bias for modeling the underlying data distribution. In this paper, we develop a general method, which we call MissDAG, to perform causal discovery from data with incomplete observations. Focusing mainly on the assumptions of ignorable missingness and the identifiable additive noise models (ANMs), MissDAG maximizes the expected likelihood of the visible part of observations under the expectation-maximization (EM) framework. In the E-step, in cases where computing the posterior distributions of parameters in closed-form is not feasible, Monte Carlo EM is leveraged to approximate the likelihood. In the M-step, MissDAG leverages the density transformation to model the noise distributions with simpler and specific formulations by virtue of the ANMs and uses a likelihood-based causal discovery algorithm with directed acyclic graph constraint. We demonstrate the flexibility of MissDAG for incorporating various causal discovery algorithms and its efficacy through extensive simulations and real data experiments.
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模拟DAG模型可能表现出属性,也许无意中,使其结构识别和意外地影响结构学习算法。在这里,我们表明边缘方差往往沿着仿制性添加添加剂噪声模型的因果顺序增加。我们将Varsortable介绍为衡量衡量边际差异和因果顺序的秩序之间的协议。对于通常采样的图形和模型参数,我们表明,一些连续结构学习算法的显着性能可以通过高的Varsortable解释,并通过简单的基线方法匹配。然而,这种性能可能不会转移到真实世界的数据,其中VARS使性可能是中等或取决于测量尺度的选择。在标准化数据上,相同的算法无法识别地面真理DAG或其Markov等价类。虽然标准化在边缘方差中删除了模式,但我们表明,数据产生过程,其产生高VILS使性也留下了即使在标准化之后也可以利用不同的协方差模式。我们的调查结果挑战了独立绘制参数的通用基准的重要性。代码可在https://github.com/scriddie/varsortable获得。
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贝叶斯结构学习允许人们对负责生成给定数据的因果定向无环图(DAG)捕获不确定性。在这项工作中,我们提出了结构学习(信任)的可疗法不确定性,这是近似后推理的框架,依赖于概率回路作为我们后验信仰的表示。与基于样本的后近似值相反,我们的表示可以捕获一个更丰富的DAG空间,同时也能够通过一系列有用的推理查询来仔细地理解不确定性。我们从经验上展示了如何将概率回路用作结构学习方法的增强表示,从而改善了推断结构和后部不确定性的质量。有条件查询的实验结果进一步证明了信任的表示能力的实际实用性。
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Latent variable models such as the Variational Auto-Encoder (VAE) have become a go-to tool for analyzing biological data, especially in the field of single-cell genomics. One remaining challenge is the interpretability of latent variables as biological processes that define a cell's identity. Outside of biological applications, this problem is commonly referred to as learning disentangled representations. Although several disentanglement-promoting variants of the VAE were introduced, and applied to single-cell genomics data, this task has been shown to be infeasible from independent and identically distributed measurements, without additional structure. Instead, recent methods propose to leverage non-stationary data, as well as the sparse mechanism shift assumption in order to learn disentangled representations with a causal semantic. Here, we extend the application of these methodological advances to the analysis of single-cell genomics data with genetic or chemical perturbations. More precisely, we propose a deep generative model of single-cell gene expression data for which each perturbation is treated as a stochastic intervention targeting an unknown, but sparse, subset of latent variables. We benchmark these methods on simulated single-cell data to evaluate their performance at latent units recovery, causal target identification and out-of-domain generalization. Finally, we apply those approaches to two real-world large-scale gene perturbation data sets and find that models that exploit the sparse mechanism shift hypothesis surpass contemporary methods on a transfer learning task. We implement our new model and benchmarks using the scvi-tools library, and release it as open-source software at \url{https://github.com/Genentech/sVAE}.
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本文提出了一种新的因果发现方法,即结构不可知的建模(SAM)。SAM利用条件独立性和分布不对称性,旨在从观察数据中找到潜在的因果结构。该方法基于不同玩家之间的游戏,该游戏将每个变量分布有条件地作为神经网估算,而对手则旨在区分生成的数据与原始数据。结合分布估计,稀疏性和无环限制的学习标准用于通过随机梯度下降来实施图形结构和参数的优化。SAM在合成和真实数据上进行了实验验证。
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