InfoWorld: Fired up IT: March 19, 2004: By Chad Dickerson : APPLICATION_DEVELOPMENT : APPLICATIONS
About the book: Peopleware: Productive Projects and Teams by Tom DeMarco and Timothy Lister
From the book review/article (culled from the book):
Protecting the productivity of your top performers is essential to managing successful projects. According to studies cited in the book, the best people will outperform the worst by about 10-to-1. The best performer will outperform a median performer by 2.5 times. Finally, on average, the one-half of performers who are better-than-median will typically outdo the other half by 2-to-1.