Dear Economist¹,

我今年17岁，正在学习A级(A-level)经济学。我的很多朋友都已确立了性爱关系，我自己也想谈个女朋友，但我担心那会让我的学习分心。如何对这一计划的成本-收益进行分析呢？

I am 17 years old and studying A-level economics. A lot of my friends are getting into serious relationships and I'd like to get a girlfriend myself, but I am also concerned about getting distracted from my studies. How does the cost-benefit analysis work out?

本(BEN)，白金汉郡
Ben, Buckinghamshire

亲爱的本：
Dear Ben,

很多经济学家对此都有不同看法。社会保守人士最近声称，"在结婚之前节欲能塑造人格和自我控制力。"

A lot of economists² have been arguing about this. Social conservatives have recently argued that "abstinence until marriage builds character and self-control."

更加看似有道理的一点在于--正如经济学家约瑟夫o萨比亚(Joseph Sabia)在一篇即将发表的文章中所写的那样："如果性交的实际收益高于事先的预期收益，青少年会把在投入在人力资本方面的时间和精力，转而投向未来性生活的获得。"

More plausibly³, as the economist Joseph Sabia suggests in a forthcoming article, "if the realised benefits of sexual intercourse⁴ are higher than the ex ante anticipated benefits, adolescents may substitute time and energy away from investments in human capital and towards investments in future obtainment of sex."

这意味着性可能会分心，因为它会给人带来惊人的愉悦。

In English, that means that sex may be distracting because it is surprisingly fun.

处女和处男的学习成绩更好，这点几乎毫无疑问。但这是因为性杀死了脑细胞，还是因为已经厌倦了学校生活的年轻人在更努力地寻找自娱的方式呢？在发表于《经济探究》(Economic Inquiry⁵)的文章中，萨比亚教授使用了决定开始性生活的时间数据来表明，决定开始性生活的孩子们在学校里本来表现就很糟糕。

There is little doubt that virgins⁶ achieve better grades. Yet is this because sex kills brain cells, or because kids who are already bored at school look harder for ways to amuse themselves? Professor Sabia's article in Economic Inquiry uses data on the timing⁷ of the decision to have sex to show that kids who decide to have sex were already doing badly at school.

萨比亚教授的研究结果显示，女孩子失去童贞似乎根本不能让她们分心--这或许是因为小男朋友能力还不足以让女孩们极大地分心。

Professor Sabia's results show that a girl does not seem to be distracted at all by losing her virginity - perhaps because young boyfriends are not competent enough to be terribly distracting.

但你要小心，因为对男孩子来说情况是不同的。萨比亚教授发现，开始性生活的决定会让你的学习成绩下降好几个百分点。那就是我数学成绩如此糟糕的借口，如今我依然坚持这一点。

Be careful, though, because it's different for boys. Professor Sabia finds that deciding to have sex will knock a few percentage points off your grade. That's my excuse for doing so badly at maths, and I'm sticking to it.