Statistics and Its Interface

Volume 11 (2018)

Number 1

Variable selection and direction estimation for single-index models via DC-TGDR method

Pages: 169 – 181



Wei Zhong (Wang Yanan Institute for Studies in Economics (WISE), Department of Statistics, School of Economics and Fujian Key Laboratory of Statistical Science, Xiamen University, Xiamen, Fujian, China)

Xi Liu (Department of Statistics and Applied Probability, University of California at Santa Barbara)

Shuangge Ma (Department of Biostatistics, Yale University, New Haven, Connecticut, U.S.A.; and Wang Yanan Institute for Studies in Economics (WISE), Department of Statistics and School of Economics, Xiamen University, Xiamen, Fujian, China)


This paper is concerned with selecting important covariates and estimating the index direction simultaneously for high dimensional single-index models. We develop an efficient Threshold Gradient Directed Regularization method via maximizing Distance Covariance (DC-TGDR) between the single index and response variable. Due to the appealing property of distance covariance which can measure nonlinear dependence between random variables, the proposed method avoids estimating the unknown link function of the single index and dramatically reduces computational complexity compared to other methods that use smoothing techniques. It keeps the model-free advantage from the view of sufficient dimension reduction and requires neither predictors nor response variable to be continuous. In addition, the DC-TGDR method encourages a grouping effect. That is, it is capable of choosing highly correlated covariates in or out of the model together. We examine finite-sample performance of the proposed method by Monte Carlo simulations. In a real data analysis, we identify important copy number alterations (CNAs) for gene expression.


distance covariance, high-dimensional data, threshold gradient directed regularization, single-index models, variable selection

Wei Zhong’s research was supported by NNSFC grants 11301435 and 11671334.

Received 11 November 2016

Published 23 August 2017