This Chapter provides a survey of the economics literature on multi-sided platforms with particular focus on competition policy issues, including market definition, mergers, monopolization, and coordinated behavior. It provides a survey of the general industrial organization theory of...

We estimate the demand for a videocalling technology in the presence of both network effects and heterogeneity. Using a unique dataset from a large multinational firm, we pose and estimate a fully dynamic model of technology adoption. We propose a novel identification strategy based on...

This paper investigates how the destabilizing of a social network may increase the scope of network externalities, using data on sales of a video-calling system made to an investment bank's employees and subsequent usage by these customers. The terrorist attacks of 2001 led potential customers...

In this paper we examine the importance of local spillovers such as network externalities and learning from others in the diffusion of home computers using data on 110,000 U.S. households in 1997. Controlling for many individual characteristics, we find that people are more likely to buy their...

We examine the role of network effects in the demand for pharmaceuticals at both the brand level and for a therapeutic class of drugs. These effects emerge when use of a drug by others conveys information about its efficacy and safety to patients and physicians. This can lead to herd behavior...

The paper uses disaggregated data on asset holdings and liabilities to estimate a general equilibrium model where each institution determines the diversification and size of the asset and liability sides of its balance-sheet. The model endogenously generates two types of financial networks: (i)...

The move from traditional to open-access journals—which charge no subscription fees, only submission fees—is gaining support in academia. We analyze a two-sided-market model in which journals cannot commit to subscription fees when authors (who prefer low subscription fees because this...

Using staggered entry of two dockless bikesharing firms, we find the entrant expands the market for the incumbent. The entry helps the incumbent to serve a greater number of trips, make more bike investment, achieve higher revenue per trip, improve bike utilization rate, and form a wider and...

Celebrity endorsements are often sought to influence public opinion. We ask whether celebrity endorsement per se has an effect beyond the fact that their statements are seen by many, and whether on net their statements actually lead people to change their beliefs. To do so, we conducted a...

Fifteen years after German reunification, the facts about slow regional convergence have born out the prediction of Barro (1991), except that migration out of East Germany has not slowed down. I document that in particular the 18-29 year old are leaving East Germany, and that the emigration has...