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Reliable outlier detection in high-dimensional data is crucial in modern science, yet it remains a challenging task. Traditional methods often break down in these settings due to their reliance on asymptotic behaviors with respect to sample…

Methodology · Statistics 2025-11-05 Seong-ho Lee , Yongho Jeon

Unsupervised learning methods are well established in the area of anomaly detection and achieve state of the art performances on outlier datasets. Outliers play a significant role, since they bear the potential to distort the predictions of…

Machine Learning · Computer Science 2024-07-02 Andreas Lohrer , Daniyal Kazempour , Maximilian Hünemörder , Peer Kröger

We propose two new outlier detection methods, for identifying and classifying different types of outliers in (big) functional data sets. The proposed methods are based on an existing method called Massive Unsupervised Outlier Detection…

Methodology · Statistics 2021-10-15 Oluwasegun Taiwo Ojo , Antonio Fernández Anta , Rosa E. Lillo , Carlo Sguera

This paper studies the outlier detection problem from the point of view of penalized regressions. Our regression model adds one mean shift parameter for each of the $n$ data points. We then apply a regularization favoring a sparse vector of…

Methodology · Statistics 2011-10-18 Yiyuan She , Art B. Owen

Most of the existing methods for anomaly detection use only positive data to learn the data distribution, thus they usually need a pre-defined threshold at the detection stage to determine whether a test instance is an outlier.…

Machine Learning · Computer Science 2019-03-19 Kai Tian , Shuigeng Zhou , Jianping Fan , Jihong Guan

We present different methods of unsupervised learning which can be used for outlier detection in high energy nuclear collisions. The UrQMD model is used to generate the bulk background of events as well as different variants of outlier…

High Energy Physics - Experiment · Physics 2021-05-26 Punnathat Thaprasop , Kai Zhou , Jan Steinheimer , Christoph Herold

This work proposes an unsupervised learning framework for trajectory (sequence) outlier detection that combines ranking tests with user sequence models. The overall framework identifies sequence outliers at a desired false positive rate…

Machine Learning · Computer Science 2021-11-09 Mohamed A. Zahran , Leonardo Teixeira , Vinayak Rao , Bruno Ribeiro

Outlier detection is the identification of points in a dataset that do not conform to the norm. Outlier detection is highly sensitive to the choice of the detection algorithm and the feature subspace used by the algorithm. Extracting…

Artificial Intelligence · Computer Science 2017-05-18 Yanjie Fu , Charu Aggarwal , Srinivasan Parthasarathy , Deepak S. Turaga , Hui Xiong

One-class classification has been a prevailing method in building deep anomaly detection models under the assumption that a dataset consisting of normal samples is available. In practice, however, abnormal samples are often mixed in a…

Machine Learning · Computer Science 2023-02-14 Minkyung Kim , Junsik Kim , Jongmin Yu , Jun Kyun Choi

The one-class anomaly detection approach has previously been found to be effective in face presentation attack detection, especially in an \textit{unseen} attack scenario, where the system is exposed to novel types of attacks. This work…

Computer Vision and Pattern Recognition · Computer Science 2018-07-04 Shervin Rahimzadeh Arashloo , Josef Kittler

Out-of-distribution (OOD) detection is indispensable for machine learning models deployed in the open world. Recently, the use of an auxiliary outlier dataset during training (also known as outlier exposure) has shown promising performance.…

Machine Learning · Computer Science 2022-06-29 Yifei Ming , Ying Fan , Yixuan Li

Outlier ensemble methods have shown outstanding performance on the discovery of instances that are significantly different from the majority of the data. However, without the awareness of fairness, their applicability in the ethical…

Machine Learning · Computer Science 2021-03-18 Haoyu Liu , Fenglong Ma , Shibo He , Jiming Chen , Jing Gao

Outlier detection amounts to finding data points that differ significantly from the norm. Classic outlier detection methods are largely designed for single data type such as continuous or discrete. However, real world data is increasingly…

Machine Learning · Statistics 2016-08-18 Kien Do , Truyen Tran , Dinh Phung , Svetha Venkatesh

Most dense recognition approaches bring a separate decision in each particular pixel. These approaches deliver competitive performance in usual closed-set setups. However, important applications in the wild typically require strong…

Computer Vision and Pattern Recognition · Computer Science 2023-04-06 Matej Grcić , Josip Šarić , Siniša Šegvić

Outlier detection is a fundamental task in data mining and has many applications including detecting errors in databases. While there has been extensive prior work on methods for outlier detection, modern datasets often have sizes that are…

Machine Learning · Computer Science 2019-08-01 Laure Berti-Equille , Ji Meng Loh , Saravanan Thirumuruganathan

Out-of-distribution (OOD) detection is an important task in machine learning systems for ensuring their reliability and safety. Deep probabilistic generative models facilitate OOD detection by estimating the likelihood of a data sample.…

Machine Learning · Computer Science 2021-06-16 Jaemoo Choi , Changyeon Yoon , Jeongwoo Bae , Myungjoo Kang

Reliable confidence estimation for deep neural classifiers is a challenging yet fundamental requirement in high-stakes applications. Unfortunately, modern deep neural networks are often overconfident for their erroneous predictions. In this…

Machine Learning · Computer Science 2023-03-31 Fei Zhu , Zhen Cheng , Xu-Yao Zhang , Cheng-Lin Liu

Universal anomaly detection still remains a challenging problem in machine learning and medical image analysis. It is possible to learn an expected distribution from a single class of normative samples, e.g., through epistemic uncertainty…

Computer Vision and Pattern Recognition · Computer Science 2023-10-03 Johanna P. Müller , Matthew Baugh , Jeremy Tan , Mischa Dombrowski , Bernhard Kainz

Often the challenge associated with tasks like fraud and spam detection is the lack of all likely patterns needed to train suitable supervised learning models. This problem accentuates when the fraudulent patterns are not only scarce, they…

Machine Learning · Computer Science 2019-05-08 Utkarsh Porwal , Smruthi Mukund

In this paper, an outlier elimination algorithm for ellipse/ellipsoid fitting is proposed. This two-stage algorithm employs a proximity-based outlier detection algorithm (using the graph Laplacian), followed by a model-based outlier…

Methodology · Statistics 2009-10-27 Jieqi Yu , Haipeng Zheng , Sanjeev R. Kulkarni , H. Vincent Poor