An Evidential Dynamic Neighborhood Approach to Learn from Imbalanced Data
摘要
Imbalanced datasets pose a significant challenge for existing k-nearest neighbor (kNN)-based methods, which often exhibit a bias toward the majority class and therefore struggle to maintain classification performance on minority-class instances. Although several strategies have been proposed to address this issue, these approaches often fail to effectively emphasize informative minority class instances in the neighborhood. To address this limitation, we propose Proximity-weighted Evidential Dynamic Neighbors (PwEDN), a method that dynamically accumulates the neighbors of a query instance by prioritizing minority-class samples while taking the underlying class distribution into account. In PwEDN, each neighbor is treated as a piece of evidence supporting the classification decision. PwEDN introduces a belief function to quantify the strength of each piece of evidence. It then applies Dempster-Shafer theory to aggregate the evidence weights and classifies the query instance to the class with maximum likelihood. Besides these, we investigate the impact of distance measures on the performance of kNN variants. Extensive experiments over thirty-two (32) benchmark imbalanced datasets demonstrate that PwEDN outperforms nine (9) familiar and state-of-the-art methods, including data-oriented techniques and kNN variants. Furthermore, the Wilcoxon signed-rank test indicates the statistical superiority of PwEDN over all competitive methods in terms of AUPRC at the 5% level of significance.