Effective Class-Imbalance Learning Based on SMOTE and Convolutional Neural Networks

TLDR

Imbalanced data, where one class vastly outnumbers another, biases machine‑learning models toward the majority class and hampers performance. This study evaluates deep‑learning approaches combined with oversampling and undersampling, proposing a CNN–SMOTE model to address class imbalance. Experiments were run 100 times on KEEL, breast‑cancer, and Z‑Alizadeh Sani datasets with random shuffling to assess the methods. The SMOTE‑Normalization‑CNN achieved 99.08 % accuracy on 24 imbalanced datasets, outperforming other techniques and demonstrating applicability to other binary classification tasks.

Abstract

Imbalanced Data (ID) is a problem that deters Machine Learning (ML) models from achieving satisfactory results. ID is the occurrence of a situation where the quantity of the samples belonging to one class outnumbers that of the other by a wide margin, making such models’ learning process biased towards the majority class. In recent years, to address this issue, several solutions have been put forward, which opt for either synthetically generating new data for the minority class or reducing the number of majority classes to balance the data. Hence, in this paper, we investigate the effectiveness of methods based on Deep Neural Networks (DNNs) and Convolutional Neural Networks (CNNs) mixed with a variety of well-known imbalanced data solutions meaning oversampling and undersampling. Then, we propose a CNN-based model in combination with SMOTE to effectively handle imbalanced data. To evaluate our methods, we have used KEEL, breast cancer, and Z-Alizadeh Sani datasets. In order to achieve reliable results, we conducted our experiments 100 times with randomly shuffled data distributions. The classification results demonstrate that the mixed Synthetic Minority Oversampling Technique (SMOTE)-Normalization-CNN outperforms different methodologies achieving 99.08% accuracy on the 24 imbalanced datasets. Therefore, the proposed mixed model can be applied to imbalanced binary classification problems on other real datasets.