Association for Public Policy Analysis & Management

The US trains a large share of the world’s PhD scientists, many of whom are students of foreign origin who then remain after completing their studies, providing an important source of highly-skilled STEM labor to the US workforce. China and India are currently the countries that send the most STEM doctoral students to the US –and are also among those with the highest stay rate – the fraction of students who stay in the US after their studies. However, the percentage with definite plans to remain in the US has recently fallen, according to NSF summary statistics. In this paper, we measure whether the actual medium run rates mirror these intentions, using newly available NSF micro-data that follows careers and locations of a sample of US-granted PhDs. We then investigate what may have caused these declines, particularly focusing on visa policy. Newly-binding country limits on permanent visas for those with advanced degrees are associated with a 10 percentage point decrease in stay rates from China and India. We also estimate that students whose graduate studies were funded by a foreign government – who typically come to the US on visas with a return requirement – are 25 percentage points more likely to leave the US, all else equal, although the fraction of students affected by these requirements is small, and they are found primarily in fields of study which may have greater applicability in the home country. By contrast the per-country permanent visa cap affects a large share of STEM PhDs who are disproportionately found in fields of study that have high potential to contribute to US economic growth but enroll relatively few natives. Finally, we measure the contribution of macroeconomic and scientific growth in the countries of origin to stay rates. These factors have less effect in attracting students home than the visa policy has in discouraging them from remaining in the US. Per-country limits thus appear to play a significant role in constraining the supply of highly skilled STEM workers in the US economy.