2月25日，美国排名第二的共和党总统候选人瑞克?桑托伦(Rick Santorum)声称奥巴马总统鼓励每个人接受大学教育为势利之举。显然，美国是势利之国。最近一项投票显示，94%的家长希望他们的子女能上大学。1月份，将近60%16-24岁的美国人被至少一所大学录取，创造了空前的记录。

　　Enrolment has been rising for decades, egged on by parents, presidents of both political stripes (not to mention Mr Santorum, when a senator) and the rising wage premium that college graduates command. The recession added an extra kick. Enrolment rose from 57% in the 2007-08 academic year to 59% in 2010-11.

　　几十年来，大学录取率持续攀升，这不仅得益于学生家长、两派总统们（更不必说当时还身为参议员的桑托伦先生）的大力支持，亦归功于大学毕业生所得工资奖励日益升高。经济衰退增加了这一趋势。录取率由2007-08学年的57%上升至2010-11学年的59%。

　　Unemployment always hits the young particularly hard, reducing the opportunity cost of going back to full-time education. An expansion of both federal Pell grants, from 5.5m in 2007-08 to 9.6m in 2011-12, and of college tax credits has helped defray costs, which may help explain why the share of students holding down jobs also dropped sharply after 2008.

　　失业总是对年轻人造成巨大的打击，这也降低了重新接受全日制教育的机会成本。而联邦佩尔奖学金以及大学课税减免的额度亦大幅提升，可以用来支付开销，前者更是由2007-08学年的550万美金上升至2011-12年的960万美金，这也很好地解释了为什么08年以后仍坚持工作的学生的比例急剧下降。

　　This trend sheds light on one of the central mysteries of the recovery: why so many people have left the labour force. The proportion of the working-age population that is working or looking for work (the participation rate) has fallen from 66% in 2007 to below 64% in January. This has been an important part of the reduction in the headline unemployment figure. With fewer people entering the labour force, there are fewer job hunters to be counted as unemployed.

　　这一趋势使得经济复苏最核心之谜浮出水面：人们放弃劳动之谜。2007年适龄劳动人口中工作或正在求职的比例（参与率）为66%，而到了今年一月份，这一比例下降到了64%，这是占据报纸头版头条的失业率下降的主要原因。进入劳动力市场的人越少，被统计的求职人员也就越少。

　　The drop has been by far the largest among 16-to-24-year-olds; their participation rate has dropped almost five percentage points since 2007. Alan Krueger, the chairman of Mr Obama’s Council of Economic Advisers, reckons this can explain almost a third of the drop in the overall participation rate.

　　目前，16-24岁的人群是参与率是下降最多的，2007年下降了将近5个百分点。奥巴马政府的经济顾问委员会会长阿兰?克鲁格（Alan Krueger）估计这（前文提到的扩招趋势）能解释为什么总参与率下降了近1/3。

　　That puts a different spin on a trend most economists have seen in a drearier light. They thought a lacklustre economy was suppressing participation by driving discouraged workers out of the labour market altogether, and that participation would rebound along with the economy. Mr Krueger agrees that part of the drop is due to lack of demand for labour because of the recession, but thinks something else is at work: the underlying trend in participation in the past decade has already been falling because of an ageing work force and a downdrift in participation by women. It may tick up in coming years as the young people now in college graduate. When they do, Mr Krueger notes, they will have more human capital, which will, with luck, earn them higher wages and boost the economy’s overall potential. Which would be all to the good, since they will have hefty student loans to repay.

　　这转变了大多数经济学家在不明朗的情势下看到的趋势。他们曾认为疲软的经济使得灰心丧气的劳动者退出劳动力市场，从而压制了参与率，经济复苏可以使得参与率回升。克鲁格先生赞同这样的观点：经济衰退降低了劳动力需求从而降低了参与率，但他认为这后面另有玄机：过去的十年里参与率已经有潜在的下降的趋势，这时由于劳动力老龄化以及女性参与率下降造成的。不过在接下来的几年里，参与率会由于现在读大学生毕业而再度上升。克鲁格先生还指出当这些大学生毕业后会拥有更高的人力资本，如果一切顺利的话，他们将因此获得更高的薪资，并促进经济总体潜力的增长。这样总得来说还是好的，因为他们须偿还巨额贷款。