activity
20072024
most citedSparsistency and rates of convergence in large covariance matrix estimation

421 citations · 495 across the 8 of their papers we have counts for

collaborators

8 papers

stat.ME2024★ 1 cited

Factor Strength Estimation in Vector and Matrix Time Series Factor Models

Weilin Chen, Clifford Lam

Most factor modelling research in vector or matrix-valued time series assume all factors are pervasive/strong and leave weaker factors and their corresponding series to the noise.…

stat.ME2022★ 3 cited

Rank and Factor Loadings Estimation in Time Series Tensor Factor Model by Pre-averaging

Weilin Chen, Clifford Lam

Tensor time series data appears naturally in a lot of fields, including finance and economics. As a major dimension reduction tool, similar to its factor model counterpart, the idi…

math.ST2018★ 4 cited

On testing for high-dimensional white noise

Zeng Li, Clifford Lam, Jianfeng Yao +1

Testing for white noise is a classical yet important problem in statistics, especially for diagnostic checks in time series modeling and linear regression. For high-dimensional tim…

math.ST2012★ 62 cited

Factor modeling for high-dimensional time series: Inference for the number of factors

Clifford Lam, Qiwei Yao

This paper deals with the factor modeling for high-dimensional time series based on a dimension-reduction viewpoint. Under stationary settings, the inference is simple in the sense…

math.ST2010★ 4 cited

Estimation for Latent Factor Models for High-Dimensional Time Series

Clifford Lam, Qiwei Yao, Neil Bathia

This paper deals with the dimension reduction for high-dimensional time series based on common factors. In particular we allow the dimension of time series to be as large as, o…

stat.ME2008

Estimation of Large Precision Matrices Through Block Penalization

Clifford Lam

This paper focuses on exploring the sparsity of the inverse covariance matrix $\bSigma^{-1}$, or the precision matrix. We form blocks of parameters based on each off-diagonal band…

math.ST2007★ 421 cited

Sparsistency and rates of convergence in large covariance matrix estimation

Clifford Lam, Jianqing Fan

This paper studies the sparsistency and rates of convergence for estimating sparse covariance and precision matrices based on penalized likelihood with nonconvex penalty functions.…

math.ST2007

Profile-Kernel likelihood inference with diverging number of parameters

C. Lam, J. Fan

The generalized varying coefficient partially linear model with growing number of predictors arises in many contemporary scientific endeavor. In this paper we set foot on both theo…