Robust Statistical Scaling of Outlier Scores: Improving the Quality of Outlier Probabilities for Outliers (Extended Version)

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Hauptverfasser: Röchner, Philipp, Marques, Henrique O., Campello, Ricardo J. G. B., Zimek, Arthur, Rothlauf, Franz
Format: Preprint
Veröffentlicht: 2024
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author Röchner, Philipp
Marques, Henrique O.
Campello, Ricardo J. G. B.
Zimek, Arthur
Rothlauf, Franz
author_facet Röchner, Philipp
Marques, Henrique O.
Campello, Ricardo J. G. B.
Zimek, Arthur
Rothlauf, Franz
contents Outlier detection algorithms typically assign an outlier score to each observation in a dataset, indicating the degree to which an observation is an outlier. However, these scores are often not comparable across algorithms and can be difficult for humans to interpret. Statistical scaling addresses this problem by transforming outlier scores into outlier probabilities without using ground-truth labels, thereby improving interpretability and comparability across algorithms. However, the quality of this transformation can be different for outliers and inliers. Missing outliers in scenarios where they are of particular interest - such as healthcare, finance, or engineering - can be costly or dangerous. Thus, ensuring good probabilities for outliers is essential. This paper argues that statistical scaling, as commonly used in the literature, does not produce equally good probabilities for outliers as for inliers. Therefore, we propose robust statistical scaling, which uses robust estimators to improve the probabilities for outliers. We evaluate several variants of our method against other outlier score transformations for real-world datasets and outlier detection algorithms, where it can improve the probabilities for outliers.
format Preprint
id arxiv_https___arxiv_org_abs_2408_15874
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Robust Statistical Scaling of Outlier Scores: Improving the Quality of Outlier Probabilities for Outliers (Extended Version)
Röchner, Philipp
Marques, Henrique O.
Campello, Ricardo J. G. B.
Zimek, Arthur
Rothlauf, Franz
Machine Learning
Artificial Intelligence
Outlier detection algorithms typically assign an outlier score to each observation in a dataset, indicating the degree to which an observation is an outlier. However, these scores are often not comparable across algorithms and can be difficult for humans to interpret. Statistical scaling addresses this problem by transforming outlier scores into outlier probabilities without using ground-truth labels, thereby improving interpretability and comparability across algorithms. However, the quality of this transformation can be different for outliers and inliers. Missing outliers in scenarios where they are of particular interest - such as healthcare, finance, or engineering - can be costly or dangerous. Thus, ensuring good probabilities for outliers is essential. This paper argues that statistical scaling, as commonly used in the literature, does not produce equally good probabilities for outliers as for inliers. Therefore, we propose robust statistical scaling, which uses robust estimators to improve the probabilities for outliers. We evaluate several variants of our method against other outlier score transformations for real-world datasets and outlier detection algorithms, where it can improve the probabilities for outliers.
title Robust Statistical Scaling of Outlier Scores: Improving the Quality of Outlier Probabilities for Outliers (Extended Version)
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2408.15874