A recent paper by McGill University's Jennifer Hunt to an NBER labour studies programme conference asks whether the increase in foreign-born college graduates has contributed to innovation in the United States. Her paper, How Much Does Immigration Boost Innovation? (PDF), finds that it does:
In this paper I have demonstrated the important boost to innovation per capita provided by skilled immigration to the United States in 1950-2000. A calculation of the effect of immigration in the 1990-2000 period puts the magnitudes of the effects in context.
The 1990-2000 increase from 2.2% to 3.5% in the share of the population composed of immigrant college graduates increased patenting by at least 81:3 = 10:4%, and perhaps by as much as 18%. The increase in the share of post-college immigrants from 0.9% to 1.6% increased patenting by at least 10.5% and perhaps by as much as 24%. The increase from 0.30% to 0.55% in the share of workers who are immigrant scientists and engineers increased patenting by at least 13% but probably by less than 23%.
While I find evidence for the crowding-out of natives in the short run, in the long run there is evidence for the reverse: that skilled natives are attracted to states or occupations with skilled immigrants. The results hint that skilled immigrants innovate more than their native counterparts, especially if they are scientists or engineers. If correct, the result could reflect higher education of immigrants within skill categories, or positive selection of immigrants in terms of ability to innovate. However, the effect of natives is not as well identified econometrically as the effect of immigrants.
These findings suggest there are clear merits in adopting policies to both attract foreign students and to retain them once they have completed their studies (as the UK and Australia, among others, currently do).