Variety and Regional Economic Growth in the Netherlands
Using data at the COROP level for the period 1996-2002, the authors find that Jacobs externalities enhance employment growth, while unrelated variety dampens unemployment growth. Productivity growth, by contrast, can be explained by traditional determinants including investments and R&D expenditures. Implications for regional policy in The Netherlands follow.
Link
http://econ.geog.uu.nl/peeg/peeg0502.pdf