What does phase containment measure in the software lifecycle?

Phase containment measures the percentage of defects that are identified and resolved within the same phase of the software development lifecycle in which they were introduced. This metric is significant because it reflects the effectiveness of the testing processes and the quality of the work being done at each phase.

By capturing defects as close to their origin as possible, teams can reduce the cost and effort associated with fixing them later in the development process. The further along a defect is found in the lifecycle, the more resources are typically required to address it, including rework on past phases and possible delays to subsequent phases. Thus, a higher phase containment percentage indicates that the team is doing well in identifying and addressing issues within the phase, leading to improved overall quality and efficiency in the project.

While other options discuss related aspects of defect management, they do not specifically address the concept of phase containment. For instance, simply counting the total number of defects does not provide insights into how well defects are being addressed in a timely manner relative to their introduction. Additionally, measuring the time taken to resolve defects or the costs associated with fixing them focuses more on the process efficiency and cost management rather than the containment aspect itself.