Appendix B. Overview of the Personal Software Process (PSP)

The question "When are you going to be done?" plagues software developers. Everyone, from the Board of Directors, which safeguards investor interests, to line managers and individual developers needs the answer. Yet it remains difficult to predict the schedule and level of quality for a software release.

As practitioners we have tried various techniques. We have " time-boxed " and "dollar-boxed" releases so that we know we are done when either the final bell rings or the money runs out. Nevertheless, we continue to issue caveats about software releases, such as "It's good enough." We write release notes describing known defects, and, to our continued shame, wait for users to find and complain about what they want fixed.

In 1986, Watts Humphrey of the Software Engineering Institute (SEI) at Carnegie Mellon University (CMU) decided to develop a process program to help tackle the "software crisis." His work produced the Capability Maturity Model (CMM), a framework that organizations use to measure their software process. We refer you to books about the CMM, and the SEI Web pages about CMM at www.sei.cmu.edu/cmm/cmms/cmms.html.

The CMM provides a five-level process improvement framework. The model describes the attributes of organizations at the various levels in the maturity framework. A Level Five organization has more "mature" software development processes than those at lower levels. The model is inclusive; the default level for any organization is Level One, and most software development organizations are at this level.