Searching for solace in bleak unemployment numbers, policy makers and commentators often cite the relatively low joblessness among college graduates, which is currently 5.1 percent compared with 10 percent for high school graduates and an overall jobless rate of 9.8 percent. Ben Bernanke, the chairman of the Federal Reserve, cited the data recently on “60 Minutes” to make the point that “educational differences” are a root cause of income inequality.