Information technology (IT) quality engineering and quality improvement methods are constantly getting more attention from world corporate leaders, all levels of management, design engineers, and academia. This trend can be seen easily by the widespread of “Six Sigma” initiatives in many Fortune IT 500 companies. For a Six Sigma initiative in IT, software design activity is the most important to achieve significant quality and reliability results. Because design activities carry a big portion of software development impact, quality improvements done in design stages often will bring the most impressive results. Patching up quality problems in post-design phases usually is inefficient and very costly.

During the last 20 years, there have been significant enhancements in software development methodologies for quality improvement in software design; those methods include the Waterfall Model, Personal Software Process (PSP), Team Software Process (TSP), Capability Maturity Model (CMM), Software Process Improvement Capability Determination (SPICE), Linear Sequential Model, Prototyping Model, RAD Model, and Incremental Model, among others.1 The historical evolution of these methods and processes, although indicating improvement trends, indicates gaps that each method tried to pick up where its predecessors left off while filling the gaps missed in their application.