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Assessing variability according to distinct factors in data is a fundamental technique of statistics. The method commonly regarded to as analysis of variance (ANOVA) is, however, typically confined to the case where all levels of a factor…

Methodology · Statistics 2013-03-15 Steven Geinitz , Reinhard Furrer

This paper is motivated by medical studies in which the same patients with multiple sclerosis are examined at several successive visits and described by fractional anisotropy tract profiles, which can be represented as functions. Since the…

Methodology · Statistics 2023-06-07 Katarzyna Kuryło , Łukasz Smaga

Manifold-valued functional data analysis (FDA) recently becomes an active area of research motivated by the raising availability of trajectories or longitudinal data observed on non-linear manifolds. The challenges of analyzing such data…

Machine Learning · Statistics 2022-05-27 Zhengwu Zhang , Bayan Saparbayeva

Real-world deployment of machine learning models is challenging because data evolves over time. While no model can work when data evolves in an arbitrary fashion, if there is some pattern to these changes, we might be able to design methods…

Machine Learning · Computer Science 2024-05-03 Rasool Fakoor , Jonas Mueller , Zachary C. Lipton , Pratik Chaudhari , Alexander J. Smola

Measurement system analysis aims to quantify the variability in data attributable to the measurement system and evaluate its contribution to overall data variability. This paper conducts a rigorous theoretical investigation of the…

Applications · Statistics 2025-01-31 Banafsheh Lashkari , Shojaeddin Chenouri

When functional data manifest amplitude and phase variations, a commonly-employed framework for analyzing them is to take away the phase variation through a function alignment and then to apply standard tools to the aligned functions. A…

Methodology · Statistics 2017-05-30 Sungwon Lee , Sungkyu Jung

This paper explores the nonparametric estimation of the volatility component in a heteroscedastic scalar-on-function regression model, where the underlying discrete-time process is ergodic and subject to a missing-at-random mechanism. We…

Methodology · Statistics 2024-12-17 Abdelbasset Djeniah , Mohamed Chaouch , Amina Angelika Bouchentouf

Shape-constrained functional data encompass a wide array of application fields, such as activity profiling, growth curves, healthcare and mortality. Most existing methods for general functional data analysis often ignore that such data are…

Methodology · Statistics 2024-08-13 Poorbita Kundu , Hans-Georg Müller

In many longitudinal settings, time-varying covariates may not be measured at the same time as responses and are often prone to measurement error. Naive last-observation-carried-forward methods incur estimation biases, and existing…

Methodology · Statistics 2023-03-10 Xinyue Chang , Yehua Li , Yi Li

We propose modeling raw functional data as a mixture of a smooth function and a high-dimensional factor component. The conventional approach to retrieving the smooth function from the raw data is through various smoothing techniques.…

Methodology · Statistics 2022-04-13 Yuan Gao , Han Lin Shang , Yanrong Yang

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

There are often two important types of variation in functional data: the horizontal (or phase) variation and the vertical (or amplitude) variation. These two types of variation have been appropriately separated and modeled through a domain…

Statistics Theory · Mathematics 2013-04-26 Xiaosun Lu , J. S. Marron

We develop a method for constructing tolerance bounds for functional data with random warping variability. In particular, we define a generative, probabilistic model for the amplitude and phase components of such observations, which…

Computation · Statistics 2019-07-24 J. Derek Tucker , John R. Lewis , Caleb King , Sebastian Kurtek

Missingness and measurement frequency are two sides of the same coin. How frequent should we measure clinical variables and conduct laboratory tests? It depends on many factors such as the stability of patient conditions, diagnostic…

Machine Learning · Computer Science 2024-02-16 Jiacheng Liu , Jaideep Srivastava

In this paper we consider aggregated functional data composed by a linear combination of component curves and the problem of estimating these component curves. We propose the application of a bayesian wavelet shrinkage rule based on a…

Methodology · Statistics 2022-06-01 Alex Rodrigo dos Santos Sousa

Motivated by distinct walking patterns in real-world free-living gait data, this paper proposes an innovative curve-based sampling scheme for the analysis of functional data characterized by a mixture of covariance structures. Traditional…

Methodology · Statistics 2025-04-10 Yian Yu , Bo Wang , Jian Qing Shi

We propose modeling raw functional data as a mixture of a smooth function and a highdimensional factor component. The conventional approach to retrieving the smooth function from the raw data is through various smoothing techniques.…

Methodology · Statistics 2021-02-05 Yuan Gao , Han Lin Shang , Yanrong Yang

When the study variable is functional and storage capacities are limited or transmission costs are high, selecting with survey sampling techniques a small fraction of the observations is an interesting alternative to signal compression…

Statistics Theory · Mathematics 2013-02-15 Hervé Cardot , Camelia Goga , Pauline Lardin

We propose VarFA, a variational inference factor analysis framework that extends existing factor analysis models for educational data mining to efficiently output uncertainty estimation in the model's estimated factors. Such uncertainty…

Machine Learning · Statistics 2020-08-18 Zichao Wang , Yi Gu , Andrew Lan , Richard Baraniuk

We consider parameter estimation, hypothesis testing and variable selection for partially time-varying coefficient models. Our asymptotic theory has the useful feature that it can allow dependent, nonstationary error and covariate…

Statistics Theory · Mathematics 2012-08-20 Ting Zhang , Wei Biao Wu