Gene Epstein writes in the March 1, 2010 issue of Barron's:
All we have are figures on the stock of consumer and business debt, from which inferences about a credit crunch have been drawn. But while credit-crunchists cite no direct data on new credit extensions, economist and statistician Jason Benderly of Benderly Economics has been able to approximate the various flows in a way that works surprisingly well. His findings are plausible and straightforward.
The Stock of Credit and the Credit-Crunch Fallacy
The main money flows in the economy.
Click the image to get to a full-size diagram.