Social Capital and Innovation: Evidence from Facebook Friendship Networks

Using Facebook friendship data, we study how three aspects of social capital shape innovative activity. We find that the most important aspect of social capital in explaining innovation is Economic Connectedness (EC)--the share of high-income friendships. One standard deviation greater EC is associated with 97% more patents per capita among patenting ZIP Codes and 45% more breakthrough patents per capita among ZIP Codes with breakthrough patents. Reverse-causality tests, a within-inventor relocation design, and a quasi-experiment using fracking-driven economic shocks to non-local friends support a causal interpretation. Mechanism tests provide evidence consistent with a financing channel.