conditional independence
6739d8df16b5bce3587ca5f18662a6aa-Supplemental-Conference.pdf
Here we provide proofs of the statements made in the main text as well as further figures of numerical experiments and a more detailed discussion of heteroskedasticity effects regarding causal discovery. Let (Xi,Yi)i=1,...,n be an independent sample with Pearson correlation coefficient ฯ, and we assume the linear model Yi = Xiฮฒ +h(Zi)ฯตi, where Zi and ฯตi are independent and standard normal, and his the noise scaling function. Z. Testing whether the Pearson correlation between X and Y is zero is equivalent to testing whether the slope parameter ฮฒ is equal to zero. Therefore, this is a homoskedastic problem. A.1.2 Discussion of Effect 2: We start by discussing the homoskedastic case to see where non-constant variance of noise leads to problems within the t-test.
Useful Facts
A.1 Relation of Inverse Covariance Matrix and Partial Correlation For a covariance matrix of joint distribution for variables X,Y, the covariance matrix is The derivation comes from the following: Lemma A.1 (Conditional independence (Adapted from [34])). Notice for arbitrary function f, E[f(X)|Y] = EL[f(X)|ฯy(Y)] with one-hot encoding of discrete variable Y. Therefore for any feature map we can also get that conditional independence ensures: This thus finishes the proof for Lemma D.4. A.3 Technical Facts for Matrix Concentration We include this covariance concentration result that is adapted from Claim A.2 in [18]: Claim A.2 (covariance concentration for gaussian variables). Let X = [x1,x2, xn]> Rn d where each xi N(0,ฮฃX). Then for any given matrix B Rd m that is of rank kand is independent of X, with probability at least 1 ฮด10 over X we have 0.9B>ฮฃXB 1 n B>X>XB 1.1B>ฮฃXB. Let X = [x1,x2, xn]> Rn d where each xi is ฯ2-sub-gaussian. Then for any given matrix B Rd m that is of rank kand is independent of X, with probability at least 1 ฮด10 over X we have 0.9B>ฮฃXB 1 n B>X>XB 1.1B>ฮฃXB. Let Z Rn k be a matrix with row vectors sampled from i.i.d Gaussian distribution N(0,ฮฃZ). Let P Rn n be a fixed projection onto a space of dimension d.
Ancestral Causal Inference
Sara Magliacane, Tom Claassen, Joris M. Mooij
Constraint-based causal discovery from limited data is a notoriously difficult challenge due to the many borderline independence test decisions. Several approaches to improve the reliability of the predictions by exploiting redundancy in the independence information have been proposed recently. Though promising, existing approaches can still be greatly improved in terms of accuracy and scalability. We present a novel method that reduces the combinatorial explosion of the search space by using a more coarse-grained representation of causal information, drastically reducing computation time. Additionally, we propose a method to score causal predictions based on their confidence. Crucially, our implementation also allows one to easily combine observational and interventional data and to incorporate various types of available background knowledge. We prove soundness and asymptotic consistency of our method and demonstrate that it can outperform the state-ofthe-art on synthetic data, achieving a speedup of several orders of magnitude. We illustrate its practical feasibility by applying it to a challenging protein data set.
Binary Expansion Group Intersection Network
Conditional independence is central to modern statistics, but beyond special parametric families it rarely admits an exact covariance characterization. We introduce the binary expansion group intersection network (BEGIN), a distribution-free graphical representation for multivariate binary data and bit-encoded multinomial variables. For arbitrary binary random vectors and bit representations of multinomial variables, we prove that conditional independence is equivalent to a sparse linear representation of conditional expectations, to a block factorization of the corresponding interaction covariance matrix, and to block diagonality of an associated generalized Schur complement. The resulting graph is indexed by the intersection of multiplicative groups of binary interactions, yielding an analogue of Gaussian graphical modeling beyond the Gaussian setting. This viewpoint treats data bits as atoms and local BEGIN molecules as building blocks for large Markov random fields. We also show how dyadic bit representations allow BEGIN to approximate conditional independence for general random vectors under mild regularity conditions. A key technical device is the Hadamard prism, a linear map that links interaction covariances to group structure.
Notes on Forrรฉ's Notion of Conditional Independence and Causal Calculus for Continuous Variables
Recently, Forrรฉ (arXiv:2104.11547, 2021) introduced transitional conditional independence, a notion of conditional independence that provides a unified framework for both random and non-stochastic variables. The original paper establishes a strong global Markov property connecting transitional conditional independencies with suitable graphical separation criteria for directed mixed graphs with input nodes (iDMGs), together with a version of causal calculus for iDMGs in a general measure-theoretic setting. These notes aim to further illustrate the motivations behind this framework and its connections to the literature, highlight certain subtlies in the general measure-theoretic causal calculus, and extend the "one-line" formulation of the ID algorithm of Richardson et al. (Ann. Statist. 51(1):334--361, 2023) to the general measure-theoretic setting.
Causal discovery with endogenous context variables
Systems with variations of the underlying generating mechanism between different contexts, i.e., different environments or internal states in which the system operates, are common in the real world, such as soil moisture regimes in Earth science. Besides understanding the shared properties of the system, in practice, the question of context-specific properties, i.e., the change in causal relationships between contexts, arises. For real-world data, contexts are often driven by system variables, e.g., precipitation highly influences soil moisture. Nevertheless, this setup needs to be studied more. To account for such endogenous contexts in causal discovery, our work proposes a constraint-based method that can efficiently discover context-specific causal graphs using an adaptive testing approach. Our approach tests conditional independence on the pooled datasets to infer the dependence between system variables, including the context, to avoid introducing selection bias. To yield context-specific insights, conditional independence is tested on context-specific data. We work out the theoretical framework for this adaptive testing approach and give a detailed discussion of the connection to structural causal models, including sufficiency assumptions, which allow to prove the soundness of our algorithm and to interpret the results causally. A simulation study to evaluate numerical properties shows that our approach behaves as expected, but also leads to a further understanding of current limitations and viable extensions.