Using a series of applied econometric approaches, the Milken Institute examined the role of high technology industries in explaining the relative economic growth of metropolitan areas. They found that high-tech activity (measured by movements in the relative metro real high-tech output index and the 1990 location quotient in high-technology activity) can explain 65 percent of the growth differential between metros in the 1990s.
Link
http://www.milkeninstitute.org/publications/publications.taf?function=detail&ID=15&cat=ResRep