Title
A Re-Balancing Strategy for Class-Imbalanced Classification Based on Instance Difficulty
Abstract
Real-world data often exhibits class-imbalanced distributions, where a few classes (a.k.a. majority classes) occupy most instances and lots of classes (a.k.a. minority classes) have few instances. Neural classification models usually perform poorly on minority classes when training on such imbalanced datasets. To improve the performance on minority classes, existing methods typically re-balance the data distribution at the class level, i.e., assigning higher weights to minority classes and lower weights to majority classes during the training process. However, we observe that even the majority classes contain difficult instances to learn. By reducing the weights of the majority classes, such instances would become more difficult to learn and hurt the overall performance consequently. To tackle this problem, we propose a novel instance-level re-balancing strategy, which dynamically adjusts the sampling probabilities of instances according to the instance difficulty. Here the instance difficulty is measured based on the learning speed of instance, which is inspired by the human-leaning process (i.e., easier instances will be learned faster). We theoretically prove the correctness and convergence of our resampling algorithm. Empirical experiments demonstrate that our method significantly outperforms state-of-the-art re-balancing methods on the class-imbalanced datasets.
Year
DOI
Venue
2022
10.1109/CVPR52688.2022.00017
2022 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)
Keywords
DocType
Volume
Machine learning
Conference
2022
Issue
ISSN
ISBN
1
1063-6919
978-1-6654-6947-0
Citations 
PageRank 
References 
0
0.34
8
Authors
6
Name
Order
Citations
PageRank
Sihao Yu100.34
Jiafeng Guo21737102.17
Ruqing Zhang31510.40
Yixing Fan420219.39
Zizhen Wang522.04
Xueqi Cheng63148247.04