While use of contract teachers provides a low-cost way to increase teacher numbers, it raises the quality concern that these less trained teachers may be less effective.  We estimate the causal contract-teacher effect on student achievement using school fixed effects and value-added models of...

We show that a combination of temporariness and spending pressure is intrinsic to the aid relationship.  In our analysis, recipients rationally discount the pronouncements of donors about the duration of their commitments because in equilibrium they know that some donors will honor those...

In mature democracies, elections discipline leaders to deliver good economic performance.  Since the fall of the Soviet Union most developing countries also hold elections, but these are often marred by illicit tactics.  Using a new global data set, this paper investigates whether these...

This paper analyses the factors that give rise to the existence of the informal economy and how it evolves over time.  Using an occupational-choice model the paper shows that at early stages of development, informal and formal markets coexist, but in the long-run the size of the informal...

We compare the most common methods for selling a company or other asset when participation is costly: a simple simultaneous auction, and a sequential process in which potential buyers decide in turn whether or not to enter the bidding.  The sequential process is always more efficient.  But...

What should be the West's top priority for climate-change policy?  This article is a revsied and updated version of my talk to the Potsdam Global Sustainability Symposium (which drafted the "Potsdam Declaration" presented to the 2007 UN Climate Change Conference in Bali).

Do relative concerns on visible consumption give rise to economic distortions?  We re-examine the question posited by Arrow and Dasgupta (2009) building upon their theoretical framework but recognizing that relative concerns can only apply to visible goods (e.g., cars, clothing, jewelry) and...

 I use variation in childhood exposure to the Dust Bowl, an environmental shock to health and income, as a natural experiment to explain variation in adult human capital.  I find that the Dust Bowl produced significant adverse impacts in later life, especially when exposure was in utero,...

A vector autoregression is singular when explosive characteristic roots have geometric multiplicity larger than one.  The singular component is a mixingale.  Martingale decompositions are constructed for sample moments involving the singular component.  This permits weak and strong analysis...

This paper discusses the incentive to bundle when consumer valuations are non-additive and/or when products are supplied by separate sellers.  Whether integrated or separate, a firm has an incentive to introduce a bundle discount when demand for the bundle is more elastic than the overall...