Social relationships channel information, influence, and access to scarce resources. As a consequence, social networks - the patterns of these relationships across the members of a community - influence who comes up with important innovations, whether and how rapidly those innovations get...

In many industries, production resides in a small number of highly concentrated regions; for example, several high tech industries cluster in Silicon Valley. Explanations for this phenomenon have focused on how the co-location of firms in an industry might increase the efficiency of production....