Collaborative Research MOD: Contributions of Foreign Students to Knowledge Creation and Diffusion

自上世纪80年代以来，在美国接受教育的科学家和工程师中，在外国出生的比例大幅增长。这些学生中的大多数仍然留在美国工作。许多人担心这种增长可能对美国和原籍国产生负面影响。然而，培养外国人攻读科学和工程博士学位也有许多潜在的好处。这个项目对文献有两个重要贡献。首先，通过分析外国出生的美国博士获得者的母国和美国之间的专利引用模式，本研究调查了获得美国博士学位的外国理工科学生是否有助于将知识从美国传播到其他国家，或者知识是否从其他国家流向美国。该研究还实证检验了知识传播是否依赖于博士学位获得者留在美国。一个主要的识别策略是利用外国富布赖特奖学金作为博士学位获得者博士后位置的工具，因为富布赖特研究员在毕业后两年内不能返回美国。其次，该研究试图确定在美国接受教育的外国学生是否不成比例地促进了科学和工程知识创造、创新和创业的增长。最后，由于担心如果外国学生大量回国可能给美国带来损失，第三个子项目考虑了哪些因素会影响博士学位获得者在完成学业后离开美国的决定。两个主要来源是：(1)基于美国三所大型大学的博士和硕士毕业生早期职业生涯的数据集，以及(2)来自NSF的SESTAT数据库的数据。科学家获取和利用他人创造的科技知识的程度是经济增长的一个重要决定因素。物理接近、社会网络、协作和企业间流动都被证明在知识传播中发挥着重要作用。本研究通过考察教育引起的国际流动在解释全球知识扩散中的作用，对这一主题的现有文献做出了贡献。一些研究人员认为，外国出生的科学家是美国知识创造和创新的力量源泉。这方面的证据主要集中在最成功的科学家或非常具体的环境中（例如，对硅谷外国出生的企业家的调查）。本研究通过检验在一个随机的科学家样本中，外国出生的科学家是否比本土出生的科学家更有可能申请专利和从事创业企业，以及他们的专利是否更有可能导致创业活动，进一步推动了分析。经济学家还没有详细研究获得美国科学和工程学位的外国学生离开美国的决定。这些主题与资助机构有关，特别是NSF和NIH，以确定最有效地利用他们的研究和培训资金。通过研究当世界上最有才华的科学家在美国接受教育时，美国和外国分别获得了多少收益，这项研究揭示了机构是否应该将更多的研究生和博士后教育资金投向外国人。此外，它将有助于围绕高技能移民及其获得学生签证和H1-B签证的政策辩论。最后，它将帮助政策制定者预测科学和工程博士课程中外国学生份额的未来趋势，并评估其潜在影响。

Since the 1980s, the foreign-born share of scientists and engineers educated in the U.S. has grown substantially. The majority of these students remain to work in the U.S. Many concerns have been raised about possible negative effects of this increase on the U.S. and on the sending countries. However, there are also many potential benefits associated with educating foreigners for Ph.D.s in science and engineering. This project has two significant contributions to the literature. First, by analyzing patent citation patterns between foreign-born U.S. Ph.D. recipients' home country and the U.S., this study investigates whether foreign science and engineering students receiving U.S. doctorates help diffuse knowledge from the U.S. to other countries or whether knowledge flows from other countries to the U.S. The study also empirically tests whether knowledge diffusion depends on the doctoral recipients staying in the U.S. Because the decision to return home is not strictly exogenous, a major identification strategy uses the Foreign Fulbright Fellowship as an instrument for the post-doctoral location of Ph.D. recipients since Fulbright fellows cannot return to the U.S. for two years after graduation. Second, the study attempts to determine whether foreign students educated in the U.S. contribute disproportionately to increases in the rate of science and engineering knowledge creation, innovation, and entrepreneurship. Finally, because of concern over potential losses to the U.S. if foreign students return home in larger numbers, a third sub-project considers what factors affect the decision of doctorate recipients to leave the U.S. after completing their studies. The two main sources are: (1) a data set based on the early careers of Ph.D. and Masters graduates from three large U.S. universities, and (2) data from the NSF's SESTAT database. The extent to which scientists can access and make use of scientific and technological knowledge produced by others is an important determinant of economic growth. Physical proximity, social networks, collaboration, and interfirm mobility have all been shown to play important roles in diffusing knowledge. This study contributes to the existing literature on this topic by examining the role of education-induced international mobility in explaining global knowledge diffusion. Some researchers argue that foreign-born scientists are a source of strength for U.S. knowledge creation and innovation. Evidence of this has focused on the most successful scientists or on very specific settings (e.g. a survey of foreign-born entrepreneurs in Silicon Valley). The present study pushes the analysis further by examining whether, in a random sample of scientists, foreign-born scientists are more likely than the native-born to patent and to engage in entrepreneurial enterprises, and whether their patenting is more likely to lead to entrepreneurial activity. The decision of foreign students who receive U.S. science and engineering degrees to leave the U.S. has not been studied at length by economists. These topics are relevant to funding agencies, particularly the NSF and NIH, in determining the most effective uses of their funding dollars for research and training. By addressing whether and how much the U.S. and foreign countries respectively gain when the world's most talented scientists are educated in the U.S., this study sheds light on whether agencies should direct more funding for graduate and postdoctoral education towards foreigners. Also, it will contribute to the policy debate surrounding high-skill immigrants and their access to student and H1-B visas. Finally, it will help policymakers predict future trends in the share of foreign students in science and engineering doctoral programs and gauge their potential impacts.