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Time-varying parameter (TVP) regressions commonly assume that time-variation in the coefficients is determined by a simple stochastic process such as a random walk. While such models are capable of capturing a wide range of dynamic…

Econometrics · Economics 2021-03-01 Manfred M. Fischer , Niko Hauzenberger , Florian Huber , Michael Pfarrhofer

Clinical research often focuses on complex traits in which many variables play a role in mechanisms driving, or curing, diseases. Clinical prediction is hard when data is high-dimensional, but additional information, like domain knowledge…

Methodology · Statistics 2020-05-21 Mirrelijn M. van Nee , Lodewyk F. A. Wessels , Mark A. van de Wiel

We propose a nonparametric method for detecting nonlinear causal relationship within a set of multidimensional discrete time series, by using sparse additive models (SpAMs). We show that, when the input to the SpAM is a $\beta$-mixing time…

Machine Learning · Statistics 2018-04-27 Yingxiang Yang , Adams Wei Yu , Zhaoran Wang , Tuo Zhao

We explore time-varying networks for high-dimensional locally stationary time series, using the large VAR model framework with both the transition and (error) precision matrices evolving smoothly over time. Two types of time-varying graphs…

Methodology · Statistics 2023-02-07 Jia Chen , Degui Li , Yuning Li , Oliver Linton

Identifying co-varying causal elements in very high dimensional feature space with internal structures, e.g., a space with as many as millions of linearly ordered features, as one typically encounters in problems such as whole genome…

Methodology · Statistics 2012-06-18 Seyoung Kim , Eric P. Xing

We consider the problem of learning predictive models from longitudinal data, consisting of irregularly repeated, sparse observations from a set of individuals over time. Such data often exhibit {\em longitudinal correlation} (LC)…

Machine Learning · Statistics 2019-11-25 Junjie Liang , Dongkuan Xu , Yiwei Sun , Vasant Honavar

Estimation of covariance matrices is a fundamental problem in multivariate statistics. Recently, growing efforts have focused on incorporating covariate effects into these matrices, facilitating subject-specific estimation. Despite these…

Methodology · Statistics 2026-04-10 Rakheon Kim , Emma Jingfei Zhang

We propose a flexible dual functional factor model for modelling high-dimensional functional time series. In this model, a high-dimensional fully functional factor parametrisation is imposed on the observed functional processes, whereas a…

Econometrics · Economics 2024-01-15 Chenlei Leng , Degui Li , Hanlin Shang , Yingcun Xia

High-dimensional variable selection, with many more covariates than observations, is widely documented in standard regression models, but there are still few tools to address it in non-linear mixed-effects models where data are collected…

Statistics Theory · Mathematics 2024-04-08 Marion Naveau , Guillaume Kon Kam King , Renaud Rincent , Laure Sansonnet , Maud Delattre

Variable selection remains a difficult problem, especially for generalized linear mixed models (GLMMs). While some frequentist approaches to simultaneously select joint fixed and random effects exist, primarily through the use of…

Methodology · Statistics 2024-12-03 Feng Ding , Ian Laga

Sparse modelling or model selection with categorical data is challenging even for a moderate number of variables, because one parameter is roughly needed to encode one category or level. The Group Lasso is a well known efficient algorithm…

Methodology · Statistics 2022-11-14 Szymon Nowakowski , Piotr Pokarowski , Wojciech Rejchel , Agnieszka Sołtys

Studies involving both randomized experiments as well as observational data typically involve time-to-event outcomes such as time-to-failure, death or onset of an adverse condition. Such outcomes are typically subject to censoring due to…

Methodology · Statistics 2023-02-27 Chirag Nagpal , Vedant Sanil , Artur Dubrawski

In this paper, we study a smoothness regularization method for a varying coefficient model based on sparse and irregularly sampled functional data which is contaminated with some measurement errors. We estimate the one-dimensional…

Methodology · Statistics 2017-11-28 Behdad Mostafaiy

We consider the problems of variable selection and estimation in nonparametric additive regression models for high-dimensional data. In recent years, several methods have been proposed to model nonlinear relationships when the number of…

Methodology · Statistics 2013-10-07 Linn Cecilie Bergersen , Kukatharmini Tharmaratnam , Ingrid K. Glad

Eliminating the effect of confounding in observational studies typically involves fitting a model for an outcome adjusted for covariates. When, as often, these covariates are high-dimensional, this necessitates the use of sparse estimators…

Methodology · Statistics 2019-03-26 Oliver Dukes , Stijn Vansteelandt

This paper addresses estimation in a longitudinal regression model for association between a scalar outcome and a set of longitudinally-collected functional covariates or predictor curves. The framework consists of estimating a time-varying…

Applications · Statistics 2020-06-30 Madan G. Kundu , Jaroslaw Harezlak , Timothy W. Randolph

In this paper, we consider voxel selection for functional Magnetic Resonance Imaging (fMRI) brain data with the aim of finding a more complete set of probably correlated discriminative voxels, thus improving interpretation of the discovered…

Computer Vision and Pattern Recognition · Computer Science 2015-06-09 Yilun Wang , Junjie Zheng , Sheng Zhang , Xujun Duan , Huafu Chen

We propose two novel approaches for estimating time-varying effects of functional predictors within a linear functional Cox model framework. This model allows for time-varying associations of a functional predictor observed at baseline,…

Methodology · Statistics 2024-12-20 Hongyu Du , Andrew Leroux

Motivated by recent work studying massive imaging data in the neuroimaging literature, we propose multivariate varying coefficient models (MVCM) for modeling the relation between multiple functional responses and a set of covariates. We…

Statistics Theory · Mathematics 2013-02-19 Hongtu Zhu , Runze Li , Linglong Kong

We introduce Targeted Smooth Bayesian Causal Forests (tsBCF), a nonparametric Bayesian approach for estimating heterogeneous treatment effects which vary smoothly over a single covariate in the observational data setting. The tsBCF method…