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We introduce an online outlier detection algorithm to detect outliers in a sequentially observed data stream. For this purpose, we use a two-stage filtering and hedging approach. In the first stage, we construct a multi-modal probability…

Machine Learning · Computer Science 2018-03-13 Mohammadreza Mohaghegh Neyshabouri , Suleyman Serdar Kozat

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

We propose a new assumption in outlier detection: Normal data instances are commonly located in the area that there is hardly any fluctuation on data density, while outliers are often appeared in the area that there is violent fluctuation…

Machine Learning · Computer Science 2020-06-09 Ding Liu , Hui Li

Methods for unsupervised anomaly detection suffer from the fact that the data is unlabeled, making it difficult to assess the optimality of detection algorithms. Ensemble learning has shown exceptional results in classification and…

Machine Learning · Statistics 2016-10-26 Edward Yu , Parth Parekh

A new semi-supervised ensemble algorithm called XGBOD (Extreme Gradient Boosting Outlier Detection) is proposed, described and demonstrated for the enhanced detection of outliers from normal observations in various practical datasets. The…

Machine Learning · Computer Science 2020-09-22 Yue Zhao , Maciej K. Hryniewicki

Analyzing sequence data usually leads to the discovery of interesting patterns and then anomaly detection. In recent years, numerous frameworks and methods have been proposed to discover interesting patterns in sequence data as well as…

Databases · Computer Science 2021-12-01 Wensheng Gan , Lili Chen , Shicheng Wan , Jiahui Chen , Chien-Ming Chen

Outlier detection refers to the identification of data points that deviate from a general data distribution. Existing unsupervised approaches often suffer from high computational cost, complex hyperparameter tuning, and limited…

Machine Learning · Computer Science 2022-08-26 Zheng Li , Yue Zhao , Xiyang Hu , Nicola Botta , Cezar Ionescu , George H. Chen

Many machine learning classification systems lack competency awareness. Specifically, many systems lack the ability to identify when outliers (e.g., samples that are distinct from and not represented in the training data distribution) are…

Machine Learning · Computer Science 2020-07-03 Matthew Cook , Alina Zare , Paul Gader

Weighted Outlier Detection is a method for identifying unusual or anomalous data points in a dataset, which can be caused by various factors like human error, fraud, or equipment malfunctions. Detecting outliers can reveal vital information…

Machine Learning · Computer Science 2023-06-13 Ravindrakumar Purohit , Jai Prakash Verma , Rachna Jain , Madhuri Bhavsar

There exist multiple methods to detect outliers in multivariate data in the literature, but most of them require to estimate the covariance matrix. The higher the dimension, the more complex the estimation of the matrix becoming impossible…

Methodology · Statistics 2020-12-01 P. Navarro-Esteban , J. A. Cuesta-Albertos

In recent years, the usage of ensemble learning in applications has grown significantly due to increasing computational power allowing the training of large ensembles in reasonable time frames. Many applications, e.g., malware detection,…

Machine Learning · Computer Science 2021-11-18 Peter Domanski , Dirk Pflüger , Jochen Rivoir , Raphaël Latty

Outlier detection is an essential capability in safety-critical applications of supervised visual recognition. Most of the existing methods deliver best results by encouraging standard closed-set models to produce low-confidence predictions…

Computer Vision and Pattern Recognition · Computer Science 2024-09-10 Anja Delić , Matej Grcić , Siniša Šegvić

Sparse estimation methods capable of tolerating outliers have been broadly investigated in the last decade. We contribute to this research considering high-dimensional regression problems contaminated by multiple mean-shift outliers which…

Methodology · Statistics 2025-10-21 Luca Insolia , Ana Kenney , Francesca Chiaromonte , Giovanni Felici

The Dark Energy Survey is able to collect image data of an extremely large number of extragalactic objects, and it can be reasonably assumed that many unusual objects of high scientific interest are hidden inside these data. Due to the…

Astrophysics of Galaxies · Physics 2023-05-04 Lior Shamir

Out-of-distribution (OOD) object detection is an important yet underexplored task. A reliable object detector should be able to handle OOD objects by localizing and correctly classifying them as OOD. However, a critical issue arises when…

Computer Vision and Pattern Recognition · Computer Science 2026-03-18 Sadia Ilyas , Annika Mütze , Klaus Friedrichs , Thomas Kurbiel , Matthias Rottmann

A sensor network is considered where at each sensor a sequence of random variables is observed. At each time step, a processed version of the observations is transmitted from the sensors to a common node called the fusion center. At some…

Statistics Theory · Mathematics 2023-07-19 Taposh Banerjee , Venugopal V. Veeravalli

Outlier detection (OD) literature exhibits numerous algorithms as it applies to diverse domains. However, given a new detection task, it is unclear how to choose an algorithm to use, nor how to set its hyperparameter(s) (HPs) in…

Machine Learning · Computer Science 2022-10-20 Xueying Ding , Lingxiao Zhao , Leman Akoglu

This paper considers the problem of clustering a collection of unlabeled data points assumed to lie near a union of lower-dimensional planes. As is common in computer vision or unsupervised learning applications, we do not know in advance…

Information Theory · Computer Science 2013-01-31 Mahdi Soltanolkotabi , Emmanuel J. Candés

The recently introduced odd-one-out anomaly detection task involves identifying the odd-looking instances within a multi-object scene. This problem presents several challenges for modern deep learning models, demanding spatial reasoning…

Computer Vision and Pattern Recognition · Computer Science 2025-09-05 Silvio Chito , Paolo Rabino , Tatiana Tommasi

Many computer vision tasks involve processing large amounts of data contaminated by outliers, which need to be detected and rejected. While outlier detection methods based on robust statistics have existed for decades, only recently have…

Computer Vision and Pattern Recognition · Computer Science 2017-04-14 Chong You , Daniel P. Robinson , René Vidal