“…Therefore the rate under the Frobenius norm far exceeds (9) when r ≫ log ep k . When r = 1, both norms lead to the same rate and the result in (9) recovers earlier results on estimating the leading eigenvector obtained in [5,39,28].…”
Section: Main Contributionssupporting
confidence: 86%
“…Proof of Theorem 4 1 • The minimax lower bound for estimating span(V) follows straightforwardly from previous results on estimating the leading singular vector, i.e., the rank-one case (see, e.g., [5,39]). The desired lower bound (25) can be found in [12,Eq.…”
Section: Proofs Of the Lower Boundsmentioning
confidence: 87%
“…See, for instance, [16,24,32,34]. In the high-dimensional setting, various aspects of this model have been studied by several recent papers, including but not limited to [1,5,12,20,21,31,33,35]. For simplicity, we assume σ is known.…”
“…In many statistical applications, instead of the covariance matrix itself, the object of direct interest is often a lower dimensional functional of the covariance matrix, e.g., the principal subspace span(V). This problem is known in the literature as sparse PCA [5,12,20,31]. The third goal of the paper is the minimax estimation of the principal subspace span(V).…”
Section: Main Contributionsmentioning
confidence: 99%
“…where (75) follows from rank( v v ′ − vv ′ ) ≤ 2 and (76) follows from the minimax lower bound in [39, Theorem 2.1] (see also [5,Theorem 2]) for estimating the leading singular vector. 2.2 • To prove the lower bound λ 2 1 ∧ r n , consider the following (composite) hypotheses testing problem:…”
This paper considers a sparse spiked covariancematrix model in the high-dimensional setting and studies the minimax estimation of the covariance matrix and the principal subspace as well as the minimax rank detection. The optimal rate of convergence for estimating the spiked covariance matrix under the spectral norm is established, which requires significantly different techniques from those for estimating other structured covariance matrices such as bandable or sparse covariance matrices. We also establish the minimax rate under the spectral norm for estimating the principal subspace, the primary object of interest in principal component analysis. In addition, the optimal rate for the rank detection boundary is obtained. This result also resolves the gap in a recent paper by Berthet and Rigollet [2] where the special case of rank one is considered.
“…Therefore the rate under the Frobenius norm far exceeds (9) when r ≫ log ep k . When r = 1, both norms lead to the same rate and the result in (9) recovers earlier results on estimating the leading eigenvector obtained in [5,39,28].…”
Section: Main Contributionssupporting
confidence: 86%
“…Proof of Theorem 4 1 • The minimax lower bound for estimating span(V) follows straightforwardly from previous results on estimating the leading singular vector, i.e., the rank-one case (see, e.g., [5,39]). The desired lower bound (25) can be found in [12,Eq.…”
Section: Proofs Of the Lower Boundsmentioning
confidence: 87%
“…See, for instance, [16,24,32,34]. In the high-dimensional setting, various aspects of this model have been studied by several recent papers, including but not limited to [1,5,12,20,21,31,33,35]. For simplicity, we assume σ is known.…”
“…In many statistical applications, instead of the covariance matrix itself, the object of direct interest is often a lower dimensional functional of the covariance matrix, e.g., the principal subspace span(V). This problem is known in the literature as sparse PCA [5,12,20,31]. The third goal of the paper is the minimax estimation of the principal subspace span(V).…”
Section: Main Contributionsmentioning
confidence: 99%
“…where (75) follows from rank( v v ′ − vv ′ ) ≤ 2 and (76) follows from the minimax lower bound in [39, Theorem 2.1] (see also [5,Theorem 2]) for estimating the leading singular vector. 2.2 • To prove the lower bound λ 2 1 ∧ r n , consider the following (composite) hypotheses testing problem:…”
This paper considers a sparse spiked covariancematrix model in the high-dimensional setting and studies the minimax estimation of the covariance matrix and the principal subspace as well as the minimax rank detection. The optimal rate of convergence for estimating the spiked covariance matrix under the spectral norm is established, which requires significantly different techniques from those for estimating other structured covariance matrices such as bandable or sparse covariance matrices. We also establish the minimax rate under the spectral norm for estimating the principal subspace, the primary object of interest in principal component analysis. In addition, the optimal rate for the rank detection boundary is obtained. This result also resolves the gap in a recent paper by Berthet and Rigollet [2] where the special case of rank one is considered.
Abstract. The truncated singular value decomposition (SVD) of the measurement matrix is the optimal solution to the representation problem of how to best approximate a noisy measurement matrix using a low-rank matrix. Here, we consider the (unobservable) denoising problem of how to best approximate a low-rank signal matrix buried in noise by optimal (re)weighting of the singular vectors of the measurement matrix. We exploit recent results from random matrix theory to exactly characterize the large matrix limit of the optimal weighting coefficients and show that they can be computed directly from data for a large class of noise models that includes the i.i.d. Gaussian noise case.Our analysis brings into sharp focus the shrinkage-and-thresholding form of the optimal weights, the non-convex nature of the associated shrinkage function (on the singular values) and explains why matrix regularization via singular value thresholding with convex penalty functions (such as the nuclear norm) will always be suboptimal. We validate our theoretical predictions with numerical simulations, develop an implementable algorithm (OptShrink) that realizes the predicted performance gains and show how our methods can be used to improve estimation in the setting where the measured matrix has missing entries.
Principal component analysis (PCA) is one of the most commonly used
statistical procedures with a wide range of applications. This paper considers
both minimax and adaptive estimation of the principal subspace in the high
dimensional setting. Under mild technical conditions, we first establish the
optimal rates of convergence for estimating the principal subspace which are
sharp with respect to all the parameters, thus providing a complete
characterization of the difficulty of the estimation problem in term of the
convergence rate. The lower bound is obtained by calculating the local metric
entropy and an application of Fano's lemma. The rate optimal estimator is
constructed using aggregation, which, however, might not be computationally
feasible. We then introduce an adaptive procedure for estimating the principal
subspace which is fully data driven and can be computed efficiently. It is
shown that the estimator attains the optimal rates of convergence
simultaneously over a large collection of the parameter spaces. A key idea in
our construction is a reduction scheme which reduces the sparse PCA problem to
a high-dimensional multivariate regression problem. This method is potentially
also useful for other related problems.Comment: Published in at http://dx.doi.org/10.1214/13-AOS1178 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.