Returns to Education: Evidence from UK Twins: Comment
评论了Bonjour等人（2003）关于英国女性同卵双胞胎教育回报率的研究，发现其7.7%的点估计结果受一个异常双胞胎对驱动，剔除后回报率降至5.1%且仅在10%水平显著。
In an article published in the American Economic Review, Dorothe Bonjour et al. (2003) used a dataset on female monozygotic twins and showed that the within-twin estimated return to one year of education was 7.7 percent and statistically significant at the 5 percent level. This comment illustrates that the point estimate conclusion is driven by one twin pair, which is an outlier in the dataset. If one eliminates this twin pair, then the estimated return to education is 5.1 percent and statistically significant at the 10 percent level only.