It's hard to study. The initial studies were coding time, but the productivity difference comes down to a few things: * Good architecture choices. These make a

It's hard to study. The initial studies were coding time, but the productivity difference comes down to a few things: * Good architecture choices. These make a big difference in total development time. * Communications. A team of 50 1x programmers has much more overhead than a team 5 10x programmers. * What's possible. There are some things some people just can't do, even given infinite time. * Process overhead. Bad people require much more process than good people. Overall, the difference in productivity between small, good team of expensive people and large, bad teams of mediocre people is much more than 10x for complex systems. It's very small for large, simple systems (e.g. "business" systems which handle inventory, HR, etc., which just have a very large number of relatively independent simple bits). That explains super-high-profit companies like Valve. Once organizations get into the mediocre person game, it becomes almost impossible to go back. Good people won't want to work there. If they do, the amount of process will slow them down. You won't leverage them well -- you still have the communications overhead. They'll always be told what won't work. Etc.