[tomgp]

>why we don't have enough evidence based scientific studies in the world of software

If you're interested in this stuff you could do worse than checking out Andy Oram and Greg Wilsons 'Making Software: What Really Works, and Why We Believe It' a series of literature reviews on various topics including the 10x programmer thing, different development methodologies and practices. It's not perfect but it's a good start and helped me to think critically about my own practice.