• IBM's Santa Teresa Laboratory reported in the 1970s that requirements changed by 25 percent during the average software development project (Barry Boehm, Soft- ware Engineering Economics, Prentice-Hall, 1981). A company needs an empirical process to handle that amount of change.
• In "Iterative and Incremental Development: A Brief History" ( Computer, June 2003, pp. 47-56), Craig Larman and Vic Basili report on the use of incremental and iterative (empirical) processes over four decades.
• Alistair Cockburn's research on organizations internationally over a 10-year period indicates that successful projects rely on perceptive intervention by alert staff, whatever process is used.