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The treatment assignment mechanism in a randomized clinical trial can be optimized for statistical efficiency within a specified class of randomization mechanisms. Optimal designs of this type have been characterized in terms of the…

Methodology · Statistics 2025-09-03 Wei Zhang , Zhiwei Zhang , Aiyi Liu

In this paper, we investigate the randomized algorithms for block matrix multiplication from random sampling perspective. Based on the A-optimal design criterion, the optimal sampling probabilities and sampling block sizes are obtained. To…

Numerical Analysis · Mathematics 2021-05-12 Chengmei Niu , Hanyu Li

In randomized clinical trials, adjustments for baseline covariates at both design and analysis stages are highly encouraged by regulatory agencies. A recent trend is to use a model-assisted approach for covariate adjustment to gain…

Methodology · Statistics 2021-07-14 Ting Ye , Jun Shao , Yanyao Yi , Qingyuan Zhao

This paper studies methods for testing and estimating change-points in the covariance structure of a high-dimensional linear time series. The assumed framework allows for a large class of multivariate linear processes (including vector…

Statistics Theory · Mathematics 2020-01-14 Ansgar Steland

We present an algorithm that enables one to perform locally adaptive block thresholding, while maintaining image continuity. Images are divided into sub-images based some standard image attributes and thresholding technique is employed over…

Computer Vision and Pattern Recognition · Computer Science 2007-05-23 S. Hemachander , Amit Verma , Siddharth Arora , Prasanta K. Panigrahi

Markov chain Monte Carlo (MCMC) sampling is an important and commonly used tool for the analysis of hierarchical models. Nevertheless, practitioners generally have two options for MCMC: utilize existing software that generates a black-box…

We study the problem of estimating from data, a sparse approximation to the inverse covariance matrix. Estimating a sparsity constrained inverse covariance matrix is a key component in Gaussian graphical model learning, but one that is…

Machine Learning · Statistics 2011-06-28 Suvrit Sra , Dongmin Kim

Covariance matrix reconstruction is a topic of great significance in the field of one-bit signal processing and has numerous practical applications. Despite its importance, the conventional arcsine law with zero threshold is incapable of…

Signal Processing · Electrical Eng. & Systems 2023-03-30 Yu-Hang Xiao , Lei Huang , David Ramírez , Cheng Qian , Hing Cheung So

Randomized controlled trials (RCTs) are the gold standard for evaluating the causal effect of a treatment; however, they often have limited sample sizes and sometimes poor generalizability. On the other hand, non-randomized, observational…

Methodology · Statistics 2021-09-23 Shuxiao Chen , Bo Zhang , Ting Ye

The variance--covariance matrix plays a central role in the inferential theories of high-dimensional factor models in finance and economics. Popular regularization methods of directly exploiting sparsity are not directly applicable to many…

Methodology · Statistics 2012-03-15 Jianqing Fan , Yuan Liao , Martina Mincheva

Efficient estimation of high-dimensional matrices-including covariance and precision matrices-is a cornerstone of modern multivariate statistics. Most existing studies have focused primarily on the theoretical properties of the estimators…

Machine Learning · Computer Science 2026-03-31 Wan Tian , Hui Yang , Zhouhui Lian , Lingyue Zhang , Yijie Peng

Adaptive sampling algorithms are modern and efficient methods that dynamically adjust the sample size throughout the optimization process. However, they may encounter difficulties in risk-averse settings, particularly due to the challenge…

Optimization and Control · Mathematics 2025-02-17 Sandra Pieraccini , Tommaso Vanzan

In semivarying coefficient models for longitudinal/clustered data, usually of primary interest is usually the parametric component which involves unknown constant coefficients. First, we study semiparametric efficiency bound for estimation…

Methodology · Statistics 2015-09-15 Ming-Yen Cheng , Toshio Honda , Jialiang Li

Blockwise missing data occurs frequently when we integrate multisource or multimodality data where different sources or modalities contain complementary information. In this paper, we consider a high-dimensional linear regression model with…

Methodology · Statistics 2023-06-30 Fei Xue , Rong Ma , Hongzhe Li

To increase statistical efficiency in a randomized experiment, researchers often use stratification (i.e., blocking) in the design stage. However, conventional practices of stratification fail to exploit valuable information about the…

Methodology · Statistics 2025-10-28 Zikai Li

Speeding up Markov Chain Monte Carlo (MCMC) for datasets with many observations by data subsampling has recently received considerable attention. A pseudo-marginal MCMC method is proposed that estimates the likelihood by data subsampling…

Computation · Statistics 2020-04-08 Matias Quiroz , Minh-Ngoc Tran , Mattias Villani , Robert Kohn , Khue-Dung Dang

We provide in this paper a fully adaptive penalized procedure to select a covariance among a collection of models observing i.i.d replications of the process at fixed observation points. For this we generalize previous results of Bigot and…

Statistics Theory · Mathematics 2012-03-05 Rolando Biscay , Hélène Lescornel , Jean-Michel Loubes

We consider a wavelet thresholding approach to adaptive variance function estimation in heteroscedastic nonparametric regression. A data-driven estimator is constructed by applying wavelet thresholding to the squared first-order differences…

Statistics Theory · Mathematics 2008-10-28 T. Tony Cai , Lie Wang

For linear time-invariant systems with uncertain parameters belonging to a finite set, we present a purely deterministic approach to multiple-model estimation and propose an algorithm based on the minimax criterion using constrained…

Optimization and Control · Mathematics 2022-07-18 Olle Kjellqvist , Anders Rantzer

This paper considers sparse spiked covariance matrix models 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…

Statistics Theory · Mathematics 2016-03-29 Tony Cai , Zongming Ma , Yihong Wu
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