Outlier detection: How to Select k for k-nearest-neighbors-based outlier detectors

J Yang, X Tan, S Rahardja - Pattern Recognition Letters, 2023 - Elsevier
Unsupervised k-nearest-neighbor-based outlier detectors play a vital role in data science
research. However, the detectors' performance relies on the choice of the parameter k …

[HTML][HTML] Neighborhood representative for improving outlier detectors

J Yang, Y Chen, S Rahardja - Information Sciences, 2023 - Elsevier
Over the decades, traditional outlier detectors have ignored the group-level factor when
calculating outlier scores for objects in data by evaluating only the object-level factor, failing …

Outlier detection method based on high-density iteration

Y Zhou, H Xia, D Yu, J Cheng, J Li - Information Sciences, 2024 - Elsevier
In conventional outlier detection, global outliers are easily identified, but the efficacy
diminishes when faced with local outliers within clusters of varying densities. Conversely …

Smoothing Outlier Scores is All You Need to Improve Outlier Detectors

J Yang, S Rahardja, P Fränti - IEEE Transactions on …, 2023 - ieeexplore.ieee.org
We hypothesize that similar objects should have similar outlier scores. To the best of our
knowledge, all existing outlier detectors calculate the outlier score for each object …

Neighborhood averaging for improving outlier detectors

J Yang, S Rahardja, P Franti - arXiv preprint arXiv:2303.09972, 2023 - arxiv.org
We hypothesize that similar objects should have similar outlier scores. To our knowledge, all
existing outlier detectors calculate the outlier score for each object independently regardless …

Unbiased Anomalous Trajectory Detection with Hierarchical Sequence Modeling

X Kong, Y He, G Shen, J Du, Z Liu… - IEEE Transactions on …, 2024 - ieeexplore.ieee.org
Anomalous trajectory detection plays an important role in the field of trajectory big data
mining, providing significant support for identifying drivers traveling at inappropriate speeds …

Improving autoencoder-based outlier detection with adjustable probabilistic reconstruction error and mean-shift outlier scoring

X Tan, J Yang, J Chen, S Rahardja… - arXiv preprint arXiv …, 2023 - arxiv.org
Autoencoders were widely used in many machine learning tasks thanks to their strong
learning ability which has drawn great interest among researchers in the field of outlier …

Joint Selective State Space Model and Detrending for Robust Time Series Anomaly Detection

J Chen, X Tan, S Rahardja, J Yang… - arXiv preprint arXiv …, 2024 - arxiv.org
Deep learning-based sequence models are extensively employed in Time Series Anomaly
Detection (TSAD) tasks due to their effective sequential modeling capabilities. However, the …

Weakly-supervised anomaly detection for multimodal data distributions

X Tan, J Chen, S Rahardja, J Yang… - arXiv preprint arXiv …, 2024 - arxiv.org
Weakly-supervised anomaly detection can outperform existing unsupervised methods with
the assistance of a very small number of labeled anomalies, which attracts increasing …

Decompose, Attend and Detect: A Robust Framework for Time Series Anomaly Detection

J Chen, X Tan, S Rahardja - 2024 IEEE International …, 2024 - ieeexplore.ieee.org
Deep learning-based reconstruction frameworks are widely employed in Time Series
Anomaly Detection (TSAD) tasks. However, these detectors encounter challenges in …