论文标题
具有无序处理的工具变量：从研究领域回报的理论和证据
Instrumental variables with unordered treatments: Theory and evidence from returns to fields of study
论文作者
论文摘要
我们重新审视Kirkeboen等人的识别论点。 （2016年）谁表明了如何将多种无序治疗的工具与有关个人对这些治疗的排名进行识别的信息结合在一起，同时允许在治疗效果中观察到的异质性和未观察到的异质性。我们表明，其识别参数为基础的关键假设具有可检验的含义。如果违反这些假设，我们还提供了可能出现的偏见的新特征。综上所述，这些结果使研究人员不仅可以测试基本的假设，还可以争论违反这些假设的偏见是否可能在经济上有意义。在这些结果的指导下，我们估计并将收入的回报与挪威和丹麦的院长研究领域进行比较。在每个国家，我们都采用Kirkeboen等人的识别论点。 （2016年），有关录取系统中不连续性的研究领域和特定于现场工具的个人排名的数据。我们从经验上研究了两个国家的研究领域的收益以及为什么的收益是否有所不同。我们发现在研究领域的回报中，尤其是在删除了违反了识别论点基础的假设的领域之后，我们发现了较强的越野相关性。
We revisit the identification argument of Kirkeboen et al. (2016) who showed how one may combine instruments for multiple unordered treatments with information about individuals' ranking of these treatments to achieve identification while allowing for both observed and unobserved heterogeneity in treatment effects. We show that the key assumptions underlying their identification argument have testable implications. We also provide a new characterization of the bias that may arise if these assumptions are violated. Taken together, these results allow researchers not only to test the underlying assumptions, but also to argue whether the bias from violation of these assumptions are likely to be economically meaningful. Guided and motivated by these results, we estimate and compare the earnings payoffs to post-secondary fields of study in Norway and Denmark. In each country, we apply the identification argument of Kirkeboen et al. (2016) to data on individuals' ranking of fields of study and field-specific instruments from discontinuities in the admission systems. We empirically examine whether and why the payoffs to fields of study differ across the two countries. We find strong cross-country correlation in the payoffs to fields of study, especially after removing fields with violations of the assumptions underlying the identification argument.
