RT book part T1 An Analysis of Class Imbalance Challenges in Predictive Mutation Testing A1 Balderas Díaz, Sara A1 Guerrero Contreras, Gabriel José A1 Delgado Pérez, Pedro A1 Medina Bulo, María Inmaculada A2 Ingeniería Informática K1 Predictive Mutation Testing K1 class imbalance K1 machine learning K1 ensemble models K1 software testing AB This study evaluates the efficacy of Predictive Mutation Testing (PMT) models, focusing on the impact of preprocessing, class rebalancing, and model selection on predictive accuracy. By filtering unreached mutants, artificially inflated metrics caused by trivial correlations were minimized, enhancing the ability of the model to identify complex patterns. While ensemble models like CatBoost and XGBoost showed high effectiveness in detecting killed mutants, their performance in identifying survived mutants was limited, underscoring the need for refined strategies to address class imbalance. The study further identifies that previous PMT research often lacks class-specific metrics, such as the Matthews Correlation Coefficient, essential for assessing balanced performance. This oversight can yield misleading evaluations by favoring the majority class, which may falsely indicate high model reliability. Although SMOTE rebalancing improved recall for survived mutants, balancing sensitivity and precision remains challenging. The findings advocate for the development of more balanced datasets in future PMT research to enhance both accuracy and robustness in real-world testing scenarios. PB Springer SN 978-981-96-6004-9 YR 2025 FD 2025-04-21 LK http://hdl.handle.net/10498/37660 UL http://hdl.handle.net/10498/37660 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 07-nov-2026