The effect of spatial mobility and other factors on academic productivity : some evidence from a set of highly productive economists

This paper compares the average productivity of those in brain drain (migrants), brain circulation (temporary migrants) and stayers (whose entire career takes place in their country of origin) in a set of 2,530 highly productive economists that work in 2007 in a selection of the top 81 Economics departments worldwide. There are three main findings. Firstly, among nationals from the eleven countries other than the U.S. with at least one department in the sample, migrants are positively selected relative to stayers –exacerbating the brain drain problem from the sending countries point of view. Moreover, those in brain circulation are negatively selected relative to those brain-drained into the U.S. but are also generally more productive than stayers. Secondly, among U.S. nationals, the ranking is very different: brain circulation, followed by stayers, and brain drain. From a global point of view, the selection effects summarized in these two points can be seen as contributing to the best allocation of resources. Thirdly, comparisons between the average productivity of foreigners and stayers in a given geographical area are very much affected by two factors: the quality threshold that defines the base to which foreigners are compared, and the type of department where comparisons take place in a partition into five department categories. For example, in the bottom 56 departments foreigners are more productive than stayers in the total sample, but the two groups are indistinguishable in an elite consisting of 833 economists with above average productivity. In the top 25 U.S. departments the two groups are equally productive, both in the total sample and in the elite.