Transition from a plan-driven process to Scrum
Jingyue Li, Nils Brede Moe, Tore Dybå · 2010
Although Scrum is an important topic in software engineering and information systems, few longitudinal industrial studies have investigated the effects of Scrum on software quality, in terms of defects and defect density, and the quality assurance process. In this paper we report on a longitudinal study in which we have followed a project over a three-year period. We compared software quality assurance processes and software defects of the project between a 17-month phase with a plan-driven process, followed by a 20-month phase with Scrum. The results of the study did not show a significant reduction of defect densities or changes of defect profiles after Scrum was used. However, the iterative nature of Scrum resulted in constant system and acceptance testing and related defect fixing, which made the development process more efficient in terms of fewer surprises and better control of software quality and release date. In addition, software quality and knowledge sharing got more focus when using Scrum. However, Scrum put more stress and time pressure on the developers, and made them reluctant to perform certain tasks for later maintenance, such as refactoring.