Modeling the rework cycle: capturing multiple defects per task

The rework cycle is at the heart of modeling projects, one of the major research and application areas in system dynamics. The current formulations for the rework cycle assume each task is either defective or not. Yet in many projects multiple defects can occur in one task. In this study we introduce a new rework cycle formulation that accounts for multiple defects per task and flexibly captures the testing process. We compare this formulation with two established formulations from the literature. Analysis shows some differences in simulated projects' finish time and delivered quality across different models and we discuss how these differences depend on project characteristics and task structure. The new formulation could be especially useful when data on tasks, defects, and testing have different measures, and when each new defect in a task significantly increases the chances of the task being rejected. Copyright (C) John Wiley & Sons, Ltd.