How Do You Do JIT Requirements?
“What is the difference between an up-front requirements document and a fish?” said Gollum, hoping to catch the Hobbit out with his riddle. But Bilbo Baggins, though a Halfling, was an experienced Agilist. He knew the answer. “A fish rots from the head down, “ he said, “but a requirements documents rots from the bottom up”. “Curses!”, screamed Gollum, “You cheats us”. But Bilbo wasn’t cheating. He was just drawing on experience.
Detailing all of the requirements out up front is a colossal waste of effort in the development of software products. The average churn after the document has been signed off is said to be about 35%, although most software professionals when I ask them to give an estimate, tend to give me a much higher figure . In any case the point is, that by the time the requirement is reached, there’s a good chance it will have either significantly changed or disappeared completely from the To-Do list. The effort spent in eliciting needs, analysing them and documenting the system requirements that meets those needs has been wasted. That in turn entails a cost: the salaries of the professionals involved for a start. And now at least part of that effort and cost has to be spent again in understanding the new situation.
Read more here http://blog.learningtree.com/uk/how-conquer-just-in-time-requirements/
