The Evolution of Work

The division of labor first increased during industrialization and then decreased again after 1970 as job roles have expanded. We explain these trends in the organization of work through a simple model where (a) machines require standardization to exploit economies of scale and (b) more customized products are subject to trends and fashions which make production tasks less predictable and a strict division of labor impractical. At the onset of industrialization, the market supports only a small number of generic varieties which can be mass-produced under a strict division of labor. Thanks to productivity growth, niche markets gradually expand, producers eventually move into customized production and the division of labor decreases again. The model predicts capital-skill substitutability during industrialization and capital skill complementarity in the maturing industrial economy. Moreover, conventional calculations of the factor content of trade underestimate the impact of globalization because they do not take into account changes in product market competition induced by trade. We test our model by exploiting the time-lags in the introduction of bar-coding in three-digit SIC manufacturing industries in the US. We find that both increases in investments in computers and bar-coding have led to skill-upgrading. However, consistent with our model bar-coding has affected mainly the center of the skill distribution by shifting demand away from the high-school educated to the less-than-college educated.

Trust and Social Collateral

This paper builds a theory of informal contract enforcement in social networks. In our model, relationships between individuals generate social collateral that can be used to control moral hazard when agents interact in a borrowing relationship. We define trust between two agents as the maximum amount that one can borrow from the other, and derive a simple reduced form expression for trust as a function of the social network. We show that trust is higher in more connected and more homogenous societies, and relate our trust measure to commonly used network statistics. Our model predicts that dense networks generate greater welfare when arrangements typically require high trust, and loose networks create more welfare otherwise. Using data on social networks and behavior in dictator games, we document evidence consistent with the quantitative predictions of the model.

Consumption Risk-sharing in Social Networks

We build a model of informal risk-sharing among agents organized in a social network. A connection between individuals serves as collateral that can be used to enforce insurance payments. We characterize incentive compatible risk-sharing arrangements for any network structure, and develop two main results. (1) Expansive networks, where every group of agents have a large number of links with the rest of the community relative to the size of the group, facilitate better risk-sharing. In particular, “two-dimensional” village networks organized by geography are sufficiently expansive to allow very good risk-sharing. (2) In second-best arrangements, agents organize in endogenous “risksharing islands” in the network, where shocks are shared fully within but imperfectly across islands. As a result, risk-sharing in second-best arrangements is local: socially closer agents insure each other more. In an application of the model, we explore the spillover effect of development aid on the consumption of non-treated individuals.

Existence of Equilibrium in Large Double Auctions

We show the existence of a pure strategy, symmetric, increasing equilibrium in double auction markets with correlated private valuations and many participants. The equilibrium we find is arbitrarily close to fully revealing as the market size grows. Our results provide strategic foundations for price-taking behavior in large markets.

Getting Closer or Drifting Apart

Advances in communication and transportation technologies have the potential to bring people closer together and create a "global village." However, they also allow heterogeneous agents to segregate along special interests, which gives rise to communities fragmented by type rather than by geography. We show that lower communication costs should always decrease separation between individual agents even as group-based separation increases. Each measure of separation is pertinent for distinct types of social interaction. A group-based measure captures the diversity of group preferences that can have an impact on the provision of public goods. While an individual measure correlates with the speed of information transmission through the social network that affects, for example, learning about job opportunities and new technologies. We test the model by looking at coauthoring between academic economists before and during the rise of the Internet in the 1990s.Economic

Why Beauty Matters

We decompose the beauty premium in an experimental labor market where “employers” determine wages of “workers” who perform a maze-solving task. This task requires a true skill which we show to be unaffected by physical attractiveness. We find a sizable beauty premium and can identify three transmission channels: (a) physically attractive workers are more confident and higher confidence increases wages; (b) for a given level of confidence, physically attractive workers are (wrongly) considered more able by employers; (c) controlling for worker confidence, physically attractive workers have oral skills (such as communication and social skills) that raise their wages when they interact with employers. Our methodology can be adopted to study the sources of discriminatory pay differentials in other settings.Economic

What Do We Expect from Our Friends?

We conduct a field experiment in a large real-world social network to examine how subjects expect to be treated by their friends and by strangers who make allocation decisions in modified dictator games. While recipients’ beliefs accurately account for the extent to which friends will choose more generous allocations than strangers (i.e. directed altruism), recipients are not able to anticipate individual differences in the baseline altruism of allocators (measured by giving to an unnamed recipient, which is predictive of generosity towards named recipients). Recipients who are direct friends with the allocator, or even recipients with many common friends, are no more accurate in recognizing intrinsically altruistic allocators. Recipient beliefs are significantly less accurate than the predictions of an econometrician who knows the allocator’s demographic characteristics and social distance, suggesting recipients do not have information on unobservable characteristics of the allocator.dictator games, beliefs, baseline altruism, directed altruism, social networks

Competing Auctions

This paper shows that larger auctions are more efficient than smaller ones, but that despite this scale effect, two competing and otherwise identical markets or auction sites of different sizes can coexist in equilibrium. We find that the range of equilibrium market sizes depends on the aggregate buyer—seller ratio, and also whether the markets are especially thin.Economic

What Do We Expect from Our Friends?

We conduct a field experiment in a large real-world social network to examine how subjects expect to be treated by their friends and by strangers who make allocation decisions in modified dictator games. While recipients beliefs accurately account for the extent to which friends will choose more generous allocations than strangers (i.e. directed altruism), recipients are not able to anticipate individual differences in the baseline altruism of allocators (measured by giving to an unnamed recipient, which is predictive of generosity towards named recipients). Recipients who are direct friends with the allocator, or even recipients with many common friends, are no more accurate in recognizing intrinsically altruistic allocators. Recipient be- liefs are significantly less accurate than the predictions of an econometrician who knows the allocators demographic characteristics and social distance, suggesting recipients do not have information on unobservable characteristics of the allocator.dictator games, beliefs, baseline altruism, directed altruism, social networks