Your Season of Birth Tells much of you and your Background European Edition
借鉴Buckles和Hungerman（2013）的方法，发现2004至2020年间多个欧盟国家不同季度出生婴儿的母亲特征存在显著差异，这意味着出生季度在教育回报率等研究中并非有效的工具变量，部分识别技术或可弥补这一局限。
ABSTRACT I adapt the approach in Buckles and Hungerman (2013) to show that in several European Union (EU) countries, between 2004 and 2020, the characteristics of the mothers giving birth in different quarters are significantly different. An implication of this finding is that quarter of birth is not a valid instrument in several applications where it has been used, e.g. return to education, even within the EU context. Beyond standard methods, partial identification techniques may help address this limitation.