Additional Resources

Conte, S. D., H. E. Dunsmore, and V. Y. Shen. Software Engineering Metrics and Models. Menlo Park, CA: Benjamin/Cummings, 1986. Conte, Dunsmore, and Shen's book contains the definitive discussion of evaluating estimation models. It discusses the "within 25% of actual 75% of the time" criteria, as well as many other evaluation criteria.

DeMarco, Tom. Controlling Software Projects. New York, NY: Yourdon Press, 1982. DeMarco discusses the probabilistic nature of software projects.

Stutzke, Richard D. Estimating Software-Intensive Systems. Upper Saddle River, NJ: Addison-Wesley, 2005. Appendix C of Stutzke's book contains a summary of measures of estimation accuracy.