I was listening to an interview with Chris Martinson on the survival podcast.
Chris Materson is a really interesting, intelligent guy with scientific training and a thirst for numbers more details can be found about him here.
He has a free video course that you can watch on youtube (click on the image above to view it). It is very logical and well cited. I would recommend anyone who is investing at present to spend some time watching this so they can understand the major financial issues that will shape the economy in the future.