On the human-capital side, in 1995 America had the highest graduation rate in the OECD. Now it lags behind seven other countries. President Barack Obama has set a target for his country to return to the top of the graduation league by 2020, but it is unlikely to be met. Young American graduates are below the OECD average in numeracy and literacy, and are doing relatively worse than older ones. Some of the explanation lies with the poor performance of America’s schools, but the most expensive tertiary-education system in the OECD might be expected to help students catch up.

Recent work by American academics suggests that it does not. Richard Arum of New York University and Josipa Roksa of the University of Virginia, authors of “Academically Adrift”, looked at the results of 2,300 students who took the Collegiate Learning Assessment (CLA), a test of critical thinking, complex reasoning and writing, and found that 45% of the sample showed no significant gains between their first and third years. Innumeracy in America