This may seem like obvious advice. One the other hand, many projects commit to delivering their product on schedules that are 100 percent impossible. Barry Boehm has defined the "impossible region" as a relationship between the expected time to develop a product and the number of person-months (PM) to be consumed. Specifically, the elapsed time (T) from writing a software requirements specification to product delivery will not be less than 2.15 times the cube root of person-months, that is,
If you have a project that is estimated to take 5 person-months then this rule says that the project can't get finished faster than 3.7 calendar months.
Ninety-nine percent of completed projects have obeyed this rule. If you think you can do better then here are some ideas to revisit:
Reference:
Boehm, B., Software Engineering Economics, Englewood Cliffs, NJ: Prentice Hall, 1981.
