Great article in Slate.
It also shows the faulty reasoning pushed by the education-industrial complex that because, on average, college graduates earn X more than high school graduates over time, they earn that premium because of the college degree.
Obviously, other variables such as motivation, intelligence, family values and connections, already differentiate the pool of college-bound H.S. seniors from those who will not go to college. Who knows what share of that earnings premium can be attributed solely to the possession of the college degree? It may be quite small and shrinking.