Title
Stable estimation of a covariance matrix guided by nuclear norm penalties
Abstract
Estimation of a covariance matrix or its inverse plays a central role in many statistical methods. For these methods to work reliably, estimated matrices must not only be invertible but also well-conditioned. The current paper introduces a novel prior to ensure a well-conditioned maximum a posteriori (MAP) covariance estimate. The prior shrinks the sample covariance estimator towards a stable target and leads to a MAP estimator that is consistent and asymptotically efficient. Thus, the MAP estimator gracefully transitions towards the sample covariance matrix as the number of samples grows relative to the number of covariates. The utility of the MAP estimator is demonstrated in two standard applications-discriminant analysis and EM clustering-in challenging sampling regimes.
Year
DOI
Venue
2014
10.1016/j.csda.2014.06.018
Computational Statistics & Data Analysis
Keywords
DocType
Volume
em clustering,regularization,condition number,covariance estimation,discriminant analysis
Journal
80
Issue
ISSN
Citations 
1
Computational Statistics & Data Analysis 80:117-128, 2014
1
PageRank 
References 
Authors
0.35
7
2
Name
Order
Citations
PageRank
Eric C. Chi1936.89
Kenneth Lange232.80