In a celebrated 1991 paper, economists Joshua Angrist of the Massachusetts Institute of Technology and Alan Krueger of Princeton University argued that season-of-birth differences in how far children go in school is due to how school-attendance laws affect children born at different times of the year. Children born in the winter reach their 16th birthdays earlier in the year than other children, which means they can legally drop out of school sooner in the school year -- which some do, leading to lower education levels in the group.

麻省理工学院(Massachusetts Institute of Technology)经济学家安格瑞斯特(Joshua Angrist)和普林斯顿大学(Princeton University)的克鲁格(Alan Krueger)1991年发表了一篇知名的论文，文中认为，出生季节造成孩子上学时间长短差异的原因在于，义务教育法对不同季节出生的孩子的影响。冬天的孩子早于其他孩子年满16岁，这就意味着他们可以更早地合法离开学校，一些孩子正是这样做的，因此导致这一群体受教育水平较低。

There may be validity to all of that research. But if there was any truth to the pattern that Ms. Buckles and Mr. Hungerman discovered, it would question the weightiness of other factors from past research. If winter babies were more likely to come from less-privileged families, it would be natural to expect them to do more poorly in life.

这可能对所有此类研究都有效。但如果巴克尔斯和亨格曼所发现的模式是真实的，以往研究所提出的其他因素的重要性就值得怀疑。如果冬天出生的孩子更可能来自弱势家庭，那他们命运不如别人也是正常的了。

The two economists examined birth-certificate data from the Centers for Disease Control and Prevention for 52 million children born between 1989 and 2001, which represents virtually all of the births in the U.S. during those years. The same pattern kept turning up: The percentage of children born to unwed mothers, teenage mothers and mothers who hadn't completed high school kept peaking in January every year. Over the 13-year period, for example, 13.2% of January births were to teen mothers, compared with 12% in May -- a small but statistically significant difference, they say.

上述两位经济学家调查了美国疾病控制与预防中心(Centers for Disease Control and Prevention)提供的1989-2001年之间出生的5,200万人的出生证明数据，这基本上是美国在此期间的所有出生人口。同样的模式不断出现：未婚妈妈、未成年妈妈和教育程度在高中以下的妈妈生育的孩子比例在每年1月达到高峰。举例来说，在这13年中，1月份出生的孩子有13.2%母亲只有十几岁，而5月份出生的孩子这一比例为12%，二者相差不大，但在统计学上具有重要意义。