A method for finding the maximal set in excess demand

We present a polynomial time method for identifying the maximal set in excess demand at a given payoff vector. This set can be used in “large” partnership formation problems to identify the minimum element in the set of individually rational payoff vectors at which there is no overdemanded set of agents. This minimum element corresponds to the minimum Walrasian equilibrium price vector in a special case of the partnership formation problem.     

Pirates and traders: Some economics of pirate-infested seas

Even where all agents are risk-neutral, merchants can insure themselves against piracy. Such self-insurance is surprisingly invulnerable to moral hazard. Further, there exist a patrolling intensity and/or penalties for captured pirates which, along with mercantile self-insurance, could eliminate piracy.     

A dynamic theory of war and peace

In every period, an aggressive country seeks concessions from a non-aggressive country with private information about their cost. The aggressive country can force concessions via war, and both countries suffer from limited commitment. We characterize the efficient sequential equilibria. We show that war is necessary to sustain peace and that temporary wars can emerge because of the coarseness of public information. In the long run, temporary wars can be sustained only if countries are patient, if the cost of war is large, and if the cost of concessions is low.     

Evaluating Projects in a Dynamic Economy: Some New Envelope Results

Abstract. This paper deals with the modern theory of social cost–benefit analysis in a dynamic economy. The theory emphasizes the role of a comprehensive, forward-looking, dynamic welfare index within the period of the project rather than that of a project's long-term consequences. However, what constitutes such a welfare index remains controversial in the recent literature. In this paper, we attempt to shed light on the issue by deriving three equivalent cost–benefit rules for evaluating a small project. In particular, we show that the direct change in a net national product (NNP) qualifies as a convenient welfare index without involving any other induced side effects. The project evaluation criterion thus becomes the present discounted value of the direct changes in NNP over the project period. We also illustrate the application of this theory in a few stylized examples.     

A model of merchants

I propose a simple model of merchants who are specialized in buying and selling a homogeneous good. Facing the same frictions as in the buyer-seller direct trades, merchants can make profits with an ability to buy and sell many units of the good. They set the price to compete in the market and provide buyers with a strong likelihood of obtaining the good. This paper establishes a turnover equilibrium where some agents choose to become merchants endogenously. An interesting multiplicity can emerge.     

The condition of the Turking class: Are online employers fair and honest?

Critics of online labor markets claim that employer abuses are endemic in these markets. Surveying a sample of workers, I find that, on average, workers perceive online employers to be slightly fairer and more honest than offline employers.     

Foreign portfolio diversification and risk-sharing

We investigate income smoothing associated with international portfolio diversification by decomposing the net factor income (NFI) channel into interests, dividends and retained earnings, for OECD and EU countries. We find that interest receipts and equity dividend payments contribute significantly to absorb domestic income shocks. Geographically concentrated portfolios and, in particular, biases toward EU markets have a strong negative effect on the degree of risk-sharing.     

Does financial globalization promote risk sharing?

In theory, one of the main benefits of financial globalization is that it should allow for more efficient international risk sharing. In this paper, we provide an empirical evaluation of the patterns of risk sharing among different groups of countries and examine how international financial integration has affected the evolution of these patterns. Using a variety of empirical techniques, we conclude that there is at best a modest degree of international risk sharing, and certainly nowhere near the levels predicted by theory. In addition, only industrial countries have attained better risk sharing outcomes during the recent period of globalization. Developing countries have, by and large, been shut out of this benefit. Even emerging market economies, many of which have reduced capital controls and all of which have witnessed large increases in cross-border capital flows, have seen little change in their ability to share risk. We find that the composition of flows may help explain why emerging markets have not been able to realize this presumed benefit of financial globalization. In particular, our results suggest that portfolio debt, which had dominated the external liability stocks of most emerging markets until recently, is not conducive to risk sharing.