About the 10x difference in programmer productivity: it's a "leprechaun", a false myth emerged from misquoting of previous articles, poor review processes of the claims made and the generalized tendency to ape a scientific process in the software engineering world. Quite some tall claims but I have read a book that makes some good arguments supporting this as well as debunking a couple of these legends turned truths: https://leanpub.com/leprechauns