Plan for Success,Model the Cost of Quality

摘要

Developers and their management make economic tradeoffs between the short- and long-term consequences of development decisions. Quality activities, especially design and peer review, are often reduced to achieve near-term milestones. However, superficial design or peer review can have long- or intermediate-term costs greatly exceeding perceived short-term benefits. Basing these decisions on judgment rather than models subjects the decision process to bias and inconsistency. The Team Software Process (TSP) uses a simple deterministic project cost model that shows how quality steps-including design, personal reviews, and inspections-not only have long-term cost benefits, but also improve project cost and schedule performance prior to release. Use of the TSP cost and quality model explicitly accounts for the costs of quality; with the TSP cost and quality model, the value of quality-related activities can be quantitatively demonstrated to developers and other stakeholders. The TSP team's experience has been that using this model during planning improves the commitment of developers and managements to plan the resources necessary for quality development. This article includes a description of the model, a discussion of a simple implementation in a spreadsheet, and an explanation of how this model is used in some simple scenarios.