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We present a new approach to factor rotation for functional data. This is achieved by rotating the functional principal components toward a predefined space of periodic functions designed to decompose the total variation into components…

Applications · Statistics 2012-07-02 Chong Liu , Surajit Ray , Giles Hooker , Mark Friedl

A new classification method for functional data is proposed in this paper. This work is motivated by the need to identify features that discriminate between neurological conditions on which local field potentials (LFPs) were recorded.…

Methodology · Statistics 2022-02-08 Shuhao Jiao , Ron D. Frostig , Hernando Ombao

Data augmentation in feature space is effective to increase data diversity. Previous methods assume that different classes have the same covariance in their feature distributions. Thus, feature transform between different classes is…

Computer Vision and Pattern Recognition · Computer Science 2020-08-05 Yuke Zhu , Yan Bai , Yichen Wei

The paper is concerned with asymptotic properties of the principal components analysis of functional data. The currently available results assume the existence of the fourth moment. We develop analogous results in a setting which does not…

Statistics Theory · Mathematics 2018-12-10 Piotr Kokoszka , Stilian Stoev , Qian Xiong

This paper proposes a new factor rotation for the context of functional principal components analysis. This rotation seeks to re-represent a functional subspace in terms of directions of decreasing smoothness as represented by a generalized…

Methodology · Statistics 2014-07-18 Giles Hooker , Steven Roberts

Accounting for phase variability is a critical challenge in functional data analysis. To separate it from amplitude variation, functional data are registered, i.e., their observed domains are deformed elastically so that the resulting…

Methodology · Statistics 2021-08-13 Alexander Bauer , Fabian Scheipl , Helmut Küchenhoff , Alice-Agnes Gabriel

Existing approaches for multivariate functional principal component analysis are restricted to data on the same one-dimensional interval. The presented approach focuses on multivariate functional data on different domains that may differ in…

Methodology · Statistics 2017-07-10 C. Happ , S. Greven

Efficient representations of multivariate functions are critical for the design of state-of-the-art methods of data restoration and image reconstruction. In this work, we consider the representation of spatio-temporal data such as temporal…

Functional Analysis · Mathematics 2023-09-20 Tatiana A. Bubba , Glenn Easley , Tommi Heikkilä , Demetrio Labate , Jose P. Rodriguez Ayllon

We propose a novel method of finding principal components in multivariate data sets that lie on an embedded nonlinear Riemannian manifold within a higher-dimensional space. Our aim is to extend the geometric interpretation of PCA, while…

Methodology · Statistics 2024-06-05 Zhigang Yao , Benjamin Eltzner , Tung Pham

In this paper, we propose a novel model to analyze serially correlated two-dimensional functional data observed sparsely and irregularly on a domain which may not be a rectangle. Our approach employs a mixed effects model that specifies the…

Methodology · Statistics 2024-04-02 Shirun Shen , Huiya Zhou , Kejun He , Lan Zhou

Estimating accurate high-dimensional transformations remains very challenging, especially in a clinical setting. In this paper, we introduce a multiscale parameterization of deformations to enhance registration and atlas estimation in the…

Optimization and Control · Mathematics 2025-01-31 Fleur Gaudfernau , Eléonore Blondiaux , Stéphanie Allassonnière , Erwan Le Pennec

This article proposes the application of various alternative definitions of the multivariate coefficient of variation parameter in two domains: radar polarimetric time series and dynamic polarimetric speckle. In the first case, the focus is…

Image and Video Processing · Electrical Eng. & Systems 2023-06-12 Elise Colin

In functional data analysis, replicate observations of a smooth functional process and its derivatives offer a unique opportunity to flexibly estimate continuous-time ordinary differential equation models. Ramsay (1996) first proposed to…

Methodology · Statistics 2024-06-27 Edward Gunning , Giles Hooker

Nested dropout is a variant of dropout operation that is able to order network parameters or features based on the pre-defined importance during training. It has been explored for: I. Constructing nested nets: the nested nets are neural…

Machine Learning · Computer Science 2022-06-20 Yufei Cui , Yu Mao , Ziquan Liu , Qiao Li , Antoni B. Chan , Xue Liu , Tei-Wei Kuo , Chun Jason Xue

Motivated by modern observational studies, we introduce a class of functional models that expands nested and crossed designs. These models account for the natural inheritance of correlation structure from sampling design in studies where…

Applications · Statistics 2013-04-26 Haochang Shou , Vadim Zipunnikov , Ciprian M. Crainiceanu , Sonja Greven

Getting tools that allow simple representations and comparisons of a set of categorical trajectories is of major interest for statisticians. Without loosing any information, we associate to each state a binary random indicator function,…

Methodology · Statistics 2026-05-05 Hervé Cardot , Caroline Peltier

Functional principal components analysis is a popular tool for inference on functional data. Standard approaches rely on an eigendecomposition of a smoothed covariance surface in order to extract the orthonormal functions representing the…

Methodology · Statistics 2021-04-02 Tui H. Nolan , Jeff Goldsmith , David Ruppert

This paper focuses on real-time all-frequency image-based rendering using an innovative solution for run-time computation of light transport. The approach is based on new results derived for non-linear phase shifting in the Haar wavelet…

Computer Vision and Pattern Recognition · Computer Science 2017-05-23 Mais Alnasser , Hassan Foroosh

A method based on wavelet transform and genetic programming is proposed for characterizing and modeling variations at multiple scales in non-stationary time series. The cyclic variations, extracted by wavelets and smoothened by cubic…

Data Analysis, Statistics and Probability · Physics 2008-12-02 Dilip P. Ahalpara , Amit Verma , Prasanta K. Panigrahi , Jitendra C. Parikh

Nonparametric estimation of the mean and covariance functions is ubiquitous in functional data analysis and local linear smoothing techniques are most frequently used. Zhang and Wang (2016) explored different types of asymptotic properties…

Statistics Theory · Mathematics 2025-01-28 Shaojun Guo , Dong Li , Xinghao Qiao , Yizhu Wang