In economic theory, one can distinguish between variety as a source of regional knowledge spillovers, called Jacobs externalities, and variety as a portfolio protecting a region from external shocks. We argue that Jacobs externalities are best measured by related variety (within sectors), while...

We propose a framework that specifies the process of economic development as an evolutionary branching process of product innovations. Each product innovation provides a growth opportunity for an existing firm or a new firm, and for an existing city or a new city. One can then obtain both firm...

The cluster literature suffers from a number of shortcomings: (1) by and large, cluster studies do not take into account that firms in a cluster are heterogeneous in terms of capabilities; (2) cluster studies tend to overemphasize the importance of place and geographical proximity and...

The paper explains the commonalities and differences between neoclassical, institutional and evolutionary approaches that have been influential in economic geography during the last couple of decades. For all three approaches, we argue that they are in agreement in some respects and in conflict...

The relatedness between the technologies used among firms in a region is thought to affect the nature and scope of knowledge spillovers. In this paper, we set out how the concepts of technological relatedness and related variety have enriched recent literature in economic geography. First,...