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Detecting outliers which are grossly different from or inconsistent with the remaining dataset is a major challenge in real-world KDD applications. Existing outlier detection methods are ineffective on scattered real-world datasets due to…

Machine Learning · Computer Science 2009-12-30 Ke Zhang , Marcus Hutter , Huidong Jin

Automatic anomaly detection is a major issue in various areas. Beyond mere detection, the identification of the origin of the problem that produced the anomaly is also essential. This paper introduces a general methodology that can assist…

Machine Learning · Statistics 2014-09-17 Tsirizo Rabenoro , Jérôme Lacaille , Marie Cottrell , Fabrice Rossi

In object tracking, outlier is one of primary factors which degrade performance of image-based tracking algorithms. In this respect, therefore, most of the existing methods simply discard detected outliers and pay little or no attention to…

Computer Vision and Pattern Recognition · Computer Science 2014-09-16 Jae-Yeong Lee , Wonpil Yu

We propose an inlier-based outlier detection method capable of both identifying the outliers and explaining why they are outliers, by identifying the outlier-specific features. Specifically, we employ an inlier-based outlier detection…

Machine Learning · Statistics 2017-02-22 Makoto Yamada , Song Liu , Samuel Kaski

In this paper, we present a local search-based algorithm for individually fair clustering in the presence of outliers. We consider the individual fairness definition proposed in Jung et al., which requires that each of the $n$ points in the…

Data Structures and Algorithms · Computer Science 2025-10-08 Binita Maity , Shrutimoy Das , Anirban Dasgupta

We introduce a variant of the $k$-nearest neighbor classifier in which $k$ is chosen adaptively for each query, rather than supplied as a parameter. The choice of $k$ depends on properties of each neighborhood, and therefore may…

Machine Learning · Computer Science 2019-05-31 Akshay Balsubramani , Sanjoy Dasgupta , Yoav Freund , Shay Moran

Detecting test data deviating from training data is a central problem for safe and robust machine learning. Likelihoods learned by a generative model, e.g., a normalizing flow via standard log-likelihood training, perform poorly as an…

Machine Learning · Computer Science 2023-04-28 Robert Schmier , Ullrich Köthe , Christoph-Nikolas Straehle

Outlier detection can serve as an extremely important tool for researchers from a wide range of fields. From the sectors of banking and marketing to the social sciences and healthcare sectors, outlier detection techniques are very useful…

Methodology · Statistics 2023-12-12 Efthymios Costa , Ioanna Papatsouma

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

We propose a novel non-parametric adaptive anomaly detection algorithm for high dimensional data based on score functions derived from nearest neighbor graphs on $n$-point nominal data. Anomalies are declared whenever the score of a test…

Machine Learning · Computer Science 2009-10-29 Manqi Zhao , Venkatesh Saligrama

Object detection is a pivotal task in computer vision that has received significant attention in previous years. Nonetheless, the capability of a detector to localise objects out of the training distribution remains unexplored. Whilst…

Computer Vision and Pattern Recognition · Computer Science 2024-07-23 Brian K. S. Isaac-Medina , Yona Falinie A. Gaus , Neelanjan Bhowmik , Toby P. Breckon

Observations in data which are significantly different from its neighbouring points but cannot be classified as noise are known as anomalies or outliers. These anomalies are a cause of concern and a timely warning about their presence could…

Applications · Statistics 2020-06-09 Krishnam Kapoor

The isolation forest algorithm for outlier detection exploits a simple yet effective observation: if taking some multivariate data and making uniformly random cuts across the feature space recursively, it will take fewer such random cuts…

Machine Learning · Statistics 2021-11-24 David Cortes

The following detection problem is studied, in which there are $M$ sequences of samples out of which one outlier sequence needs to be detected. Each typical sequence contains $n$ independent and identically distributed (i.i.d.) continuous…

Information Theory · Computer Science 2015-10-08 Yuheng Bu , Shaofeng Zou , Yingbin Liang , Venugopal V. Veeravalli

$K$-NN classifier is one of the most famous classification algorithms, whose performance is crucially dependent on the distance metric. When we consider the distance metric as a parameter of $K$-NN, learning an appropriate distance metric…

Machine Learning · Computer Science 2019-11-26 Kun Song

The k-nearest-neighbor method performs classification tasks for a query sample based on the information contained in its neighborhood. Previous studies into the k-nearest-neighbor algorithm usually achieved the decision value for a class by…

Machine Learning · Computer Science 2018-12-10 Chengsheng Mao , Bin Hu , Lei Chen , Philip Moore , Xiaowei Zhang

Unsupervised outlier detection constitutes a crucial phase within data analysis and remains a dynamic realm of research. A good outlier detection algorithm should be computationally efficient, robust to tuning parameter selection, and…

Machine Learning · Statistics 2024-09-23 Sheikh Arafat , Na Sun , Maria L. Weese , Waldyn G. Martinez

Cybersecurity has recently gained considerable interest in today's security issues because of the popularity of the Internet-of-Things (IoT), the considerable growth of mobile networks, and many related apps. Therefore, detecting numerous…

We consider state estimation for networked systems where measurements from sensor nodes are contaminated by outliers. A new hierarchical measurement model is formulated for outlier detection by integrating the outlier-free measurement model…

Applications · Statistics 2022-11-08 Hongwei Wang , Hongbin Li , Wei Zhang , Junyi Zuo , Heping Wang , Jun Fang

Outlier detection is a well-researched and crucial problem in machine learning. However, there is little research on string data outlier detection, as most literature focuses on outlier detection of numerical data. A robust string data…

Machine Learning · Computer Science 2026-03-13 Philip Maus