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Anomaly detection aims to identify observations that deviate from expected behavior. Because anomalous events are inherently sparse, most frameworks are trained exclusively on normal data to learn a single reference model of normality. This…

Extreme value theory (EVT) provides an elegant mathematical tool for the statistical analysis of rare events. When data are collected from multiple population subgroups, because some subgroups may have less data available for extreme value…

Methodology · Statistics 2024-10-22 Koki Momoki , Takuma Yoshida

We propose a nonparametric Bayesian probabilistic latent variable model for multi-view anomaly detection, which is the task of finding instances that have inconsistent views. With the proposed model, all views of a non-anomalous instance…

Machine Learning · Statistics 2014-11-14 Tomoharu Iwata , Makoto Yamada

This paper aims to build an estimate of an unknown density of the data with measurement error as a linear combination of functions from a dictionary. Inspired by the penalization approach, we propose the weighted Elastic-net penalized…

Statistics Theory · Mathematics 2020-07-07 Xiaowei Yang , Huiming Zhang , Haoyu Wei , Shouzheng Zhang

Anomaly detection is a branch of data analysis and machine learning which aims at identifying observations that exhibit abnormal behaviour. Be it measurement errors, disease development, severe weather, production quality default(s) (items)…

Machine Learning · Statistics 2024-07-11 Pavlo Mozharovskyi , Romain Valla

We introduce an anomaly detection method for multivariate time series data with the aim of identifying critical periods and features influencing extreme climate events like snowmelt in the Arctic. This method leverages the Variational…

Machine Learning · Computer Science 2024-07-16 Tolulope Ale , Nicole-Jeanne Schlegel , Vandana P. Janeja

Several environmental phenomena can be described by different correlated variables that must be considered jointly in order to be more representative of the nature of these phenomena. For such events, identification of extremes is…

Applications · Statistics 2018-03-15 Raúl Torres , Carlo De Michele , Henry Laniado , Rosa E. Lillo

We develop a method for the evaluation of extreme event statistics associated with nonlinear dynamical systems, using a small number of samples. From an initial dataset of design points, we formulate a sequential strategy that provides the…

Machine Learning · Computer Science 2022-06-08 Mustafa A. Mohamad , Themistoklis P. Sapsis

Extremal dependence describes the strength of correlation between the largest observations of two variables. It is usually measured with symmetric dependence coefficients that do not depend on the order of the variables. In many cases,…

Methodology · Statistics 2023-01-24 Cristina Deidda , Sebastian Engelke , Carlo De Michele

We introduce a new formulation of structural causal models for extremes, called the extremal structural causal model (eSCM). Unlike conventional structural causal models, where randomness is governed by a probability distribution, eSCMs use…

Statistics Theory · Mathematics 2026-05-27 Shuyang Bai , Fei Fang , Tiandong Wang

This article provides a thorough meta-analysis of the anomaly detection problem. To accomplish this we first identify approaches to benchmarking anomaly detection algorithms across the literature and produce a large corpus of anomaly…

Artificial Intelligence · Computer Science 2016-08-29 Andrew Emmott , Shubhomoy Das , Thomas Dietterich , Alan Fern , Weng-Keen Wong

Attaining ultra-reliable communication (URC) in fifth-generation (5G) and beyond networks requires deriving statistics of channel in ultra-reliable region by modeling the extreme events. Extreme value theory (EVT) has been previously…

Information Theory · Computer Science 2024-01-12 Niloofar Mehrnia , Sinem Coleri

Conventional methods for extreme event estimation rely on well-chosen parametric models asymptotically justified from extreme value theory (EVT). These methods, while powerful and theoretically grounded, could however encounter a difficult…

Methodology · Statistics 2023-01-05 Yuanlu Bai , Henry Lam , Xinyu Zhang

Inference over tails is performed by applying only the results of extreme value theory. Whilst such theory is well defined and flexible enough in the univariate case, multivariate inferential methods often require the imposition of…

Methodology · Statistics 2017-08-11 Manuele Leonelli , Dani Gamerman

Learning how to rank multivariate unlabeled observations depending on their degree of abnormality/novelty is a crucial problem in a wide range of applications. In practice, it generally consists in building a real valued "scoring" function…

Machine Learning · Statistics 2015-02-06 Nicolas Goix , Anne Sabourin , Stéphan Clémençon

We introduce a formalization and benchmark for the unsupervised anomaly detection task in the distribution-shift scenario. Our work builds upon the iWildCam dataset, and, to the best of our knowledge, we are the first to propose such an…

Computer Vision and Pattern Recognition · Computer Science 2023-09-27 Stefan Smeu , Elena Burceanu , Andrei Liviu Nicolicioiu , Emanuela Haller

We explore the dependence structure in the sampled sequence of large networks. We consider randomized algorithms to sample the nodes and study extremal properties in any associated stationary sequence of characteristics of interest like…

Social and Information Networks · Computer Science 2015-02-25 Konstantin Avrachenkov , Natalia M. Markovich , Jithin K. Sreedharan

Multivariate extreme value statistical analysis is concerned with observations on several variables which are thought to possess some degree of tail-dependence. In areas such as the modeling of financial and insurance risks, or as the…

Applications · Statistics 2014-12-31 Alexis Bienvenüe , Christian Y. Robert

We propose a novel neural network architecture that enables non-parametric calibration and generation of multivariate extreme value distributions (MEVs). MEVs arise from Extreme Value Theory (EVT) as the necessary class of models when…

Machine Learning · Statistics 2022-03-03 Ali Hasan , Khalil Elkhalil , Yuting Ng , Joao M. Pereira , Sina Farsiu , Jose H. Blanchet , Vahid Tarokh

In most risk assessment studies, it is important to accurately capture the entire distribution of the multivariate random vector of interest from low to high values. For example, in climate sciences, low precipitation events may lead to…

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