This may be old news, but a paper by Dr. Paula Stephan in NBER's Innovation Policy and the Economy, Vol 7 (2006) just came to my attention. I count at least two very interesting observations derived from the analysis of Ph.D. migration patterns in the U.S.
1. Confirmation of what I call the Broadway Joe Problem. (i.e. QB Namath was not from New York)
Indeed, seven of the top 20 institutions education PhDs to work in industry are located in the Midwest. ... The state stay rate for PhDs working in industry is now 37 percent. ... Purdue's PhDs now overwhelmingly leave the state [of Indiana] to take employment elsewhere .... It is risky as a nation to continue to rely on the "kindness" of Midwestern states to publicly educate the high-quality S&E workforce that heads out of state upon graduation. ... [A]lmost one out of ten new PhDs going to work for industry heads to San Jose.
2. R&D focus underemphasizes entrepeneurial innovation.
Only ten of the top 20 R&D firms appear on the top 20 hiring list.
Finally, our data suggest that small firms play a larger role in innovation than R&D data would suggest. For example, while the top 200 R&D firms expend more than 70 percent of all R&D in the U.S., they hire only 39 percent of all new PhDs.