Rare anomalies require large datasets: About proving the existence of anomalies

Fuente: arXiv
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Main Authors: Klüttermann, Simon, Müller, Emmanuel
Format: Preprint
Published: 2025
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author Klüttermann, Simon
Müller, Emmanuel
author_facet Klüttermann, Simon
Müller, Emmanuel
contents Detecting whether any anomalies exist within a dataset is crucial for effective anomaly detection, yet it remains surprisingly underexplored in anomaly detection literature. This paper presents a comprehensive study that addresses the fundamental question: When can we conclusively determine that anomalies are present? Through extensive experimentation involving over three million statistical tests across various anomaly detection tasks and algorithms, we identify a relationship between the dataset size, contamination rate, and an algorithm-dependent constant $ α_{\text{algo}} $. Our results demonstrate that, for an unlabeled dataset of size $ N $ and contamination rate $ ν$, the condition $ N \ge \frac{α_{\text{algo}}}{ν^2} $ represents a lower bound on the number of samples required to confirm anomaly existence. This threshold implies a limit to how rare anomalies can be before proving their existence becomes infeasible.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09894
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Rare anomalies require large datasets: About proving the existence of anomalies
Klüttermann, Simon
Müller, Emmanuel
Machine Learning
Artificial Intelligence
Detecting whether any anomalies exist within a dataset is crucial for effective anomaly detection, yet it remains surprisingly underexplored in anomaly detection literature. This paper presents a comprehensive study that addresses the fundamental question: When can we conclusively determine that anomalies are present? Through extensive experimentation involving over three million statistical tests across various anomaly detection tasks and algorithms, we identify a relationship between the dataset size, contamination rate, and an algorithm-dependent constant $ α_{\text{algo}} $. Our results demonstrate that, for an unlabeled dataset of size $ N $ and contamination rate $ ν$, the condition $ N \ge \frac{α_{\text{algo}}}{ν^2} $ represents a lower bound on the number of samples required to confirm anomaly existence. This threshold implies a limit to how rare anomalies can be before proving their existence becomes infeasible.
title Rare anomalies require large datasets: About proving the existence of anomalies
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2508.09894