RT journal article T1 Methodological pitfalls in predictive mutation testing: threats, impact and open challenges A1 Delgado Pérez, Pedro A1 Balderas Díaz, Sara A1 Medina Bulo, María Inmaculada A1 Guerrero Contreras, Gabriel José A2 Ingeniería Informática K1 Predictive Mutation Testing (PMT) K1 Mutation testing K1 Software testing K1 Machine learning AB Predictive Mutation Testing (PMT) has emerged as a promising technique for reducing the high computational cost of traditional mutation testing. This is achieved by using predictive models to estimate mutant behavior without actually requiring their execution. However, despite its growing interest, PMT is still a young and evolving field and, therefore, its experimental studies remain particularly vulnerable to various methodological threats that may compromise the validity, comparability, and reproducibility of results. This paper aims to identify and examine key methodological threats in prior PMT studies that not only affect their validity, but may also limit the technique’s ability to reach its full predictive potential. For each of the eight identified threats, spanning the main stages of the PMT workflow, we describe its nature, analyze how it has been addressed (or overlooked) in previous work, and offer a validation list of recommended practices. We further conduct an empirical validation to substantiate the impact of these threats. In addition, based on the gaps identified in this analysis, we outline several open challenges that remain unexplored in the field, such as the lack of standardization in dataset sharing, the prevalence of Java-centric studies with method-level operators, and the challenges posed by class imbalance and project heterogeneity. This work contributes to strengthening the methodological soundness of PMT research, promoting more meaningful cross-study comparisons, and encouraging the adoption of practices that foster reproducibility, scalability, and real-world applicability. PB Springer YR 2026 FD 2026-05-21 LK http://hdl.handle.net/10498/40330 UL http://hdl.handle.net/10498/40330 LA eng NO Funding for open access publishing: Universidad de Cádiz/CBUA. This publication is part of the I+D+i grant PID2021-122215NB-C33 funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU, and by the Spanish Ministry of Science and Innovation under the Excellence Network AI4Software (Red2022-134647-T). It has also been funded by Project PR2024-028, Call for Grants to Research and Teaching Staff of the University of Cadiz, Plan Propio 2022-2023, and by Project FEDER-UCA-2024-A2-48, Regional Ministry of University, Research and Innovation of the Government of Andalusia, Programa Operativo FEDER Andalucía 2021-2027. DS Repositorio Institucional de la Universidad de Cádiz RD 08-nov-2026