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Several techniques for multivariate time series anomaly detection have been proposed recently, but a systematic comparison on a common set of datasets and metrics is lacking. This paper presents a systematic and comprehensive evaluation of…

Machine Learning · Computer Science 2021-09-24 Astha Garg , Wenyu Zhang , Jules Samaran , Savitha Ramasamy , Chuan-Sheng Foo

Anomaly detection seeks to identify unusual phenomena, a central task in science and industry. The task is inherently unsupervised as anomalies are unexpected and unknown during training. Recent advances in self-supervised representation…

Machine Learning · Computer Science 2022-10-20 Tal Reiss , Niv Cohen , Eliahu Horwitz , Ron Abutbul , Yedid Hoshen

Deep anomaly detection is a difficult task since, in high dimensions, it is hard to completely characterize a notion of "differentness" when given only examples of normality. In this paper we propose a novel approach to deep anomaly…

Machine Learning · Computer Science 2020-10-07 Lucas Deecke , Lukas Ruff , Robert A. Vandermeulen , Hakan Bilen

The problem of detecting anomalies in multiple processes is considered. We consider a composite hypothesis case, in which the measurements drawn when observing a process follow a common distribution with an unknown parameter (vector), whose…

Information Theory · Computer Science 2020-04-22 Bar Hemo , Tomer Gafni , Kobi Cohen , Qing Zhao

Anomaly activities such as robbery, explosion, accidents, etc. need immediate actions for preventing loss of human life and property in real world surveillance systems. Although the recent automation in surveillance systems are capable of…

Computer Vision and Pattern Recognition · Computer Science 2021-08-23 Snehashis Majhi , Srijan Das , Francois Bremond , Ratnakar Dash , Pankaj Kumar Sa

Anomaly detection is the process of identifying abnormal instances or events in data sets which deviate from the norm significantly. In this study, we propose a signatures based machine learning algorithm to detect rare or unexpected items…

Computational Finance · Quantitative Finance 2022-02-09 Erdinc Akyildirim , Matteo Gambara , Josef Teichmann , Syang Zhou

This paper presents a novel semiparametric method to study the effects of extreme events on binary outcomes and subsequently forecast future outcomes. Our approach, based on Bayes' theorem and regularly varying (RV) functions, facilitates a…

Econometrics · Economics 2025-02-25 Laura Liu , Yulong Wang

We propose a supervised anomaly detection method for data with inexact anomaly labels, where each label, which is assigned to a set of instances, indicates that at least one instance in the set is anomalous. Although many anomaly detection…

Machine Learning · Statistics 2019-09-12 Tomoharu Iwata , Machiko Toyoda , Shotaro Tora , Naonori Ueda

Anomaly detection methods can be very useful in identifying unusual or interesting patterns in data. A recently proposed conditional anomaly detection framework extends anomaly detection to the problem of identifying anomalous patterns on a…

Machine Learning · Computer Science 2026-05-12 Michal Valko , Gregory Cooper , Amy Seybert , Shyam Visweswaran , Melissa Saul , Miloš Hauskrecht

Anomaly detection is vital in many domains, such as finance, healthcare, and cybersecurity. In this paper, we propose a novel deep anomaly detection method for tabular data that leverages Non-Parametric Transformers (NPTs), a model…

Machine Learning · Computer Science 2024-05-03 Hugo Thimonier , Fabrice Popineau , Arpad Rimmel , Bich-Liên Doan

We propose a modified density estimation problem that is highly effective for detecting anomalies in tabular data. Our approach assumes that the density function is relatively stable (with lower variance) around normal samples. We have…

Machine Learning · Computer Science 2024-05-09 Amit Rozner , Barak Battash , Henry Li , Lior Wolf , Ofir Lindenbaum

Anomaly detection (AD), also referred to as outlier detection, is a statistical process aimed at identifying observations within a dataset that significantly deviate from the expected pattern of the majority of the data. Such a process…

Novelty detection is a process for distinguishing the observations that differ in some respect from the observations that the model is trained on. Novelty detection is one of the fundamental requirements of a good classification or…

Computer Vision and Pattern Recognition · Computer Science 2019-04-10 Mahdyar Ravanbakhsh

We consider the problem of identifying patterns in a data set that exhibit anomalous behavior, often referred to as anomaly detection. In most anomaly detection algorithms, the dissimilarity between data samples is calculated by a single…

Machine Learning · Computer Science 2013-01-08 Ko-Jen Hsiao , Kevin S. Xu , Jeff Calder , Alfred O. Hero

We introduce a new type of estimator for the spectral tail process of a regularly varying time series. The approach is based on a characterizing invariance property of the spectral tail process, which is incorporated into the new estimator…

Statistics Theory · Mathematics 2021-03-16 Holger Drees , Anja Janßen , Sebastian Neblung

The main difficulty in high-dimensional anomaly detection tasks is the lack of anomalous data for training. And simply collecting anomalous data from the real world, common distributions, or the boundary of normal data manifold may face the…

Computer Vision and Pattern Recognition · Computer Science 2021-04-27 Songmin Dai , Jide Li , Lu Wang , Congcong Zhu , Yifan Wu , Xiaoqiang Li

Data-driven methods that detect anomalies in times series data are ubiquitous in practice, but they are in general unable to provide helpful explanations for the predictions they make. In this work we propose a model-agnostic algorithm that…

Using an intrinsic approach, we study some properties of random fields which appear as tail fields of regularly varying stationary random fields. The index set is allowed to be a general locally compact Hausdorff Abelian group $\mathbb{G}$.…

Probability · Mathematics 2023-01-11 Günter Last

The aim of this work is to detect and automatically generate high-level explanations of anomalous events in video. Understanding the cause of an anomalous event is crucial as the required response is dependant on its nature and severity.…

Computer Vision and Pattern Recognition · Computer Science 2021-12-13 Stanislaw Szymanowicz , James Charles , Roberto Cipolla

Generative Adversarial Networks (GAN) are a powerful methodology and can be used for unsupervised anomaly detection, where current techniques have limitations such as the accurate detection of anomalies near the tail of a distribution. GANs…

Machine Learning · Computer Science 2022-02-03 Nikolaos Dionelis , Mehrdad Yaghoobi , Sotirios A. Tsaftaris