Three essays in applied microeconomics : of norms and networks.

Summary This thesis is organized around two themes: social norms and production networks. The first chapter focuses on a case study where social norms are used in the fight against online hate speech. Using machine learning methods, I show that denouncing hateful opinions is a way to deter further hateful speech. This effect is explained by the fact that this form of contradiction serves to communicate the presence of a social norm or accentuates its importance. Beyond anti-discrimination, this chapter can shed light on how norms influence political behavior more generally. The second chapter focuses on the role that social image tastes play in explaining the effect of social norms on behavior. Many studies show that these tastes affect people's behavior on average, but we do not yet know which individuals are most likely to adjust their behavior. I present a novel experiment designed to fill this gap. It computes an individual measure of image concern, shows that there is substantial heterogeneity, and analyzes its correlation with other social preferences. The last chapter studies production networks. Vertical integration of firms can lead to anticompetitive behavior. I discuss one such behavior, called foreclosure, in which vertically integrated firms cut off the supply of essential inputs to their competitors. I use new data on production networks to identify mergers and acquisitions between vertically related firms. I show these mergers affect the supply chains of their competitors and interpret this as evidence of foreclosure.