Flying home from Atlanta I listened to an Arming the Donkeys podcast with Dilip Soman who did some research on decision process injection. In one of the studies he gave movie goers 4 smaller bags of popcorn instead of a single glutton bucket. What he found was that they would consume less popcorn since there was a mental queue, or decision point, that the participants had to pass (do I start another bag?) in order to continue.

I think the obstacle of decision points is what makes small (2 – 3 week) iterations work.

While at HP we did 18 month, classic waterfall releases and I can’t think of a time when we make corrections mid-way through. The only time we could look at what we were doing and how was at the end.

That is 36 2-week iterations. If we had done iterative development with actual retrospectives at the end of each, who knows how much more successful the product would have been. (Or how much less frustrating working there might have been towards the end.)

Here is the link to the paper, The Effect of Partitions on Controlling Consumption (from co-author, Amar Cheema’s website).