Statistical inference under high dimensional modelings has attracted much attention due to its wide applications in many fields. In this dissertation, I propose new methods for statistical inference in high dimensional models from three aspects: inference in high dimensional semiparametric models, inference in high dimensional matrix-valued data, and inference in high dimensional measurement error misspecified models. The first project studied statistical inference in high dimensional partially linear single index models. Firstly a profile partial penalized least squares estimator for parameter estimates for the model is proposed, and its asymptotic properties are given. Then an F-type test statistic for testing the parametric components is proposed, and its theoretical properties are established. I then propose a new test for the specification testing problem of the nonparametric components. Finally, simulation studies and empirical analysis of a real-world data set are conducted to illustrate the performance of the proposed testing procedure. The second project proposes new testing procedures in high dimensional matrix-valued data. Rank is an essential attribute for a matrix. A new type of statistic is proposed, which can make inferences on the rank of the matrix-valued data. I firstly give the theoretical property of its oracle version. To overcome the problem of empirical error accumulation, a new type of sparse SVD method is proposed, and its theoretical properties are given. Based on the newly proposed sparse SVD method, I provide a sample version statistic. Theoretical properties of this sample version statistic are given. Simulation studies and two applications to surveillance video data are provided to illustrate the performance of our newly proposed method. The third project proposes a new testing method in misspecified measurement error models. The testing method can work when there is potential model misspecification and measurement error in the model. Firstly its property is studied under the low dimensional setting. Then I develop it to the high dimensional setting. Further, I propose a method that can be adaptive to the sparsity level of the true parameters under the high dimensional setting. Simulation studies and one application to a clinical trial data set are given.

• Real-world problems can be high-dimensional, complex, and noisy • More data does not imply more information • Different approaches deal with the so-called curse of dimensionality to reduce irrelevant information • A process with multidimensional information is not necessarily easy to interpret nor process • In some real-world applications, the number of elements of a class is clearly lower than the other. The models tend to assume that the importance of the analysis belongs to the majority class and this is not usually the truth • The analysis of complex diseases such as cancer are focused on more-than-one dimensional omic data • The increasing amount of data thanks to the reduction of cost of the high-throughput experiments opens up a new era for integrative data-driven approaches • Entropy-based approaches are of interest to reduce the dimensionality of high-dimensional data

Modern statistics deals with large and complex data sets, and consequently with models containing a large number of parameters. This book presents a detailed account of recently developed approaches, including the Lasso and versions of it for various models, boosting methods, undirected graphical modeling, and procedures controlling false positive selections. A special characteristic of the book is that it contains comprehensive mathematical theory on high-dimensional statistics combined with methodology, algorithms and illustrations with real data examples. This in-depth approach highlights the methods’ great potential and practical applicability in a variety of settings. As such, it is a valuable resource for researchers, graduate students and experts in statistics, applied mathematics and computer science.

High-dimensional linear models play an important role in the analysis of modern data sets. Although the estimation problem has been well understood, there is still a paucity of methods and theories on the inference problem for high-dimensional linear models. This thesis focuses on statistical inference for high-dimensional linear models and consists of the following three parts. 1. The first part of the thesis considers confidence intervals for linear functionals in high-dimensional linear regression. We first establish the convergence rates of the minimax expected length for confidence intervals. Furthermore, we investigate the problem of adaptation to sparsity for the construction of confidence intervals and identify the regimes in which it is possible to construct adaptive confidence intervals. 2. In the second part of the thesis, we consider point and interval estimation of the lq loss of a given estimator in high-dimensional linear regression. For the class of rate-optimal estimators, we establish the minimax rates for estimating their lq losses, the minimax expected length of confidence intervals for their lq losses and the possibility of adaptivity of confidence intervals for their lq losses. 3. In the third part of the thesis, we consider the problem in the framework of high-dimensional instrumental variable regression and construct confidence intervals for the treatment effect in the presence of possibly invalid instrumental variables. We develop a novel selection procedure, Two-Stage Hard Thresholding (TSHT) to select valid instrumental variables and construct honest confidence intervals for the treatment effect using the selected instrumental variables.

This textbook provides a step-by-step introduction to the tools and principles of high-dimensional statistics. Each chapter is complemented by numerous exercises, many of them with detailed solutions, and computer labs in R that convey valuable practical insights. The book covers the theory and practice of high-dimensional linear regression, graphical models, and inference, ensuring readers have a smooth start in the field. It also offers suggestions for further reading. Given its scope, the textbook is intended for beginning graduate and advanced undergraduate students in statistics, biostatistics, and bioinformatics, though it will be equally useful to a broader audience.

This book features research contributions from The Abel Symposium on Statistical Analysis for High Dimensional Data, held in Nyvågar, Lofoten, Norway, in May 2014. The focus of the symposium was on statistical and machine learning methodologies specifically developed for inference in “big data” situations, with particular reference to genomic applications. The contributors, who are among the most prominent researchers on the theory of statistics for high dimensional inference, present new theories and methods, as well as challenging applications and computational solutions. Specific themes include, among others, variable selection and screening, penalised regression, sparsity, thresholding, low dimensional structures, computational challenges, non-convex situations, learning graphical models, sparse covariance and precision matrices, semi- and non-parametric formulations, multiple testing, classification, factor models, clustering, and preselection. Highlighting cutting-edge research and casting light on future research directions, the contributions will benefit graduate students and researchers in computational biology, statistics and the machine learning community.