Unlike software process metrics that are used for strategic purposes, software project metrics are tactical. That is , project metricsand the indicators derived from them are used by a project manager and a software team to adapt project workflow and technical activities.
The first application of project metrics on most software projects occurs during estimation. Metrics collected from past projects are used as a basis from which effort and time estimates are made for current software work. As a project proceeds, measures of effort and calendar time expended are compared to original estimates. The project manager uses these data to monitor and control progress.
As technical work commences, other project metrics begin to have significance. Production rates represented in terms of models created, review hours, function points, and delivered source lines are measured. In addition, erors uncovered during each software engineering task are tracked. As the software evolves from requirements into design, technical metrics are collected to assess design quality and to provide indicators that will influence the approachtaken to code generation and testing.
The intent of project metrics is twofold. First, these metrics are used to minimize the developing schedule by making the adjustments necessary to avoid delays and mitigate potential problems and risks. Second, project metrics are used to assess product quality on an ongoin basis and when, necessary, modify the technical approach to improve quality.
As quality improves, defects are minimized, and as the defect count goes down, the amount of rework required during the project is also reduced. This leads to a reduction in overall project cost.
