We explain persistent differences in cultural traits of immigrant groups with the presence of community leaders. Leaders infl uence the cultural traits of their community, which have an impact on the group's earnings. They determine whether a community will be more assimilated and wealthier or less assimilated and poorer. With a leader, cultural integration remains incomplete. The leader chooses more distinctive cultural traits in high-productivity environments and if the community is more connected. Lump-sum transfers to immigrants can hinder cultural integration. These fi ndings are in line with integration patterns of various ethnic and religious groups.

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Many models have been developed to forecast the spread of the COVID-19 virus. We present one that is enhanced to allow individuals to alter their behavior in response to the virus. We show how adding this feature to the model both changes the resulting forecast and informs our understanding of the appropriate policy response. We find that when left to their own devices, individuals do curb their social activity in the face of risk, but not as much as a government planner would. The planner fully internalizes the effect of all individuals’ actions on others in society, while individuals do not. Further, our simulations suggest that government intervention may be particularly important in the middle and later stages of a pandemic.

This paper studies bargaining and exchange in a networked market with intermediation. Possibilities to trade are restricted through a network of existing relationships and traders bargain over the division of available gains from trade along different feasible routes. Using a stochastic model of bargaining, I characterize stationary equilibrium payoffs as the fixed point of a set of intuitive value function equations and study efficiency and the relationship between network structure and payoffs. In equilibrium, trade is never unduly delayed but it may take place too early and in states where delay would be efficient. The inefficiency arises from a hold-up threat and the inability of bargaining parties credibly to commit to a split in a future period. The model also shows how with competing trade routes as trade frictions go to zero agents that are not essential to a trade opportunity receive a payoff of zero.

Many of the models used to track, forecast, and inform the response to epidemics such as COVID-19 assume that everyone has an equal chance of encountering those who are infected with a disease. But this assumption does not reflect the fact that individuals interact mostly within much narrower groups. We argue that incorporating a network perspective, which accounts for patterns of real-world interactions, into epidemiological models provides useful insights into the spread of infectious diseases.