EFC-Tomek: An effective undersampling technique for credit card fraud detection

Detecting credit card fraud is a major challenge because fraudulent transactions represent only a small fraction of financial data. Traditional methods like SMOTE (Synthetic Minority Oversampling Technique) help balance datasets but can also introduce noise and make models over- fit, reducing their effectiveness. To tackle the issues that come with oversampling, we present the Enhanced Fraud Classifier with Tomek Links (EFC-Tomek) framework. This approach builds on the existing EFN-SMOTE but takes a different approach, using Tomek Links undersampling instead of SMOTE oversampling to balance the dataset. Our main goal is to improve data quality and enhance the model’s ability to detect fraud more accurately and effectively. To test EFC- Tomek, we used two real-world datasets: European cardholders and Loan Prediction. We evaluated its performance using a number of classifiers, such as Random Forest, eXtreme Gradient Boosting, Logistic Regression, Gradient Boosting, Artificial Neural Networks, and Support Vector Classifier. The results showed that EFC-Tomek improved fraud detection, with ANN achieving the highest accuracy on both datasets.