Abstract
Data Envelopment Analysis (DEA) plays a pivotal role in assessing production unit efficiency. This study extends group efficiency assessment within the banking sector by utilizing the Modified Semi-Oriented Radial Measure (MSORM) model, specifically designed to handle negative data. It introduces two distinct efficiency definitions and develops models for their evaluation within these groups. Focusing on banks as decision-making units, the MSORM model delves into the intricacies of group efficiency. By effectively addressing negative data complexities, it enables a comprehensive evaluation of bank efficiency across various group frameworks. The study further examines the efficacy of efficiency definitions based on average and weakest performances within the MSORM framework. Empirical findings reveal significant variations in group efficiency assessment under different paradigms, highlighting the impact of the evaluation approach. This research contributes valuable insights into performance variations within the banking industry and aids in enhancing efficiency evaluations in banking systems.