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arXiv 1902.09353stat.ME
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基于置换的逆协方差估计的贝叶斯方法

A permutation-based Bayesian approach for inverse covariance estimation

Xuan Cao, Shaojun Zhang

摘要:

多维数据集的协方差估计与选择是现代统计学中的一个基本问题。高斯图形模型是用于此目的的一类流行的模型。目前高斯图形模型下逆协方差阵估计的贝叶斯方法需要底层图形,因此变量的排序是已知的。然而,在实践中,关于真正的基本模型的这种信息往往是不可用的。因此,我们提出了一种新的基于置换的贝叶斯方法来解决未知变量排序问题。特别是,我们对每个排列利用DAG-Wishart先验下的多个最大后验估计,然后构造逆协方差阵的最终估计。该估计量具有较小的变异性并具有阶不变性质。我们建立后验收敛率在温和的假设下,并通过仿真研究表明,我们的方法优于现有的方法在估计逆协方差阵。

英文摘要:

Covariance estimation and selection for multivariate datasets in a high-dimensional regime is a fundamental problem in modern statistics. Gaussian graphical models are a popular class of models used for this purpose. Current Bayesian methods for inverse covariance matrix estimation under Gaussian graphical models require the underlying graph and hence the ordering of variables to be known. However, in practice, such information on the true underlying model is often unavailable. We therefore propose a novel permutation-based Bayesian approach to tackle the unknown variable ordering issue. In particular, we utilize multiple maximum a posteriori estimates under the DAG-Wishart prior for each permutation, and subsequently construct the final estimate of the inverse covariance matrix. The proposed estimator has smaller variability and yields order-invariant property. We establish posterior convergence rates under mild assumptions and illustrate that our method outperforms existing approaches in estimating the inverse covariance matrices via simulation studies.

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