Industrial Clustering and the Returns to Inventive Activity: Canadian Biotechnology Firms, 1991-2000
The authors examine how industrial clustering affects biotechnology firms innovativeness, contrasting similar firms not located in clusters or located in clusters that are or are not focused on the firms technological specialization. Using detailed firm level data, they find clustered firms are eight times more innovative than geographically remote firms, with largest effects for firms located in clusters strong in their own specialization.
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http://www.druid.dk/wp/pdf_files/04-03.pdf