The objective of this paper is to empirically examine the importance of the structure of agglomeration on productivity and growth. The authors include the degree of co-agglomeration of similar industries as an explanatory variable in the empirical analysis, while simultaneously controlling for the degree of industry-specific agglomeration. The empirical analysis confirms a positive statistical relationship between interdependent and co-located industries on labour productivity.
Link
http://www.infra.kth.se/cesis/documents/WP71.pdf