Outlier Detection Ensemble with Embedded Feature Selection
This work addresses the issue of noisy data in outlier detection for domains requiring reliable anomaly identification, though it is incremental as it builds on existing ensemble and feature selection methods.
The paper tackled the problem of suboptimal feature selection in outlier detection by proposing an ensemble framework that unifies feature selection and outlier detection into a pairwise ranking formulation, achieving superior performance validated on 12 real-world datasets.
Feature selection places an important role in improving the performance of outlier detection, especially for noisy data. Existing methods usually perform feature selection and outlier scoring separately, which would select feature subsets that may not optimally serve for outlier detection, leading to unsatisfying performance. In this paper, we propose an outlier detection ensemble framework with embedded feature selection (ODEFS), to address this issue. Specifically, for each random sub-sampling based learning component, ODEFS unifies feature selection and outlier detection into a pairwise ranking formulation to learn feature subsets that are tailored for the outlier detection method. Moreover, we adopt the thresholded self-paced learning to simultaneously optimize feature selection and example selection, which is helpful to improve the reliability of the training set. After that, we design an alternate algorithm with proved convergence to solve the resultant optimization problem. In addition, we analyze the generalization error bound of the proposed framework, which provides theoretical guarantee on the method and insightful practical guidance. Comprehensive experimental results on 12 real-world datasets from diverse domains validate the superiority of the proposed ODEFS.