When people share risk in financial markets, intermediaries provide costly enforcement for most trades and, hence, are an integral part of financial markets' organization. We assess the degree of risk sharing that can be achieved through financial markets when enforcement is based on the threat...

This paper shows that the value function describing efficient risk sharing with limited commitment is not necessarily differentiable everywhere. We link differentiability of the value function to history dependence of efficient allocations and provide sufficient conditions for both properties.

Recently, Shimotsu and Phillips (2005) developed a new semiparametric estimator, the exact local Whittle (ELW) estimator, of the memory parameter (d) in fractionally integrated processes. The ELW estimator has been shown to be consistent and have the same N(0,1/4) limit distribution for all...

This paper studies the optimal commodity taxation problem when time taken in consumption is a perfect substitute for either labor or leisure. It shows that while labor substitutability affects the optimal tax structure, leisure substitutability leaves the classical optimal tax results intact. In...

Using the Mirrlees optimal income tax model with a maxi-min social welfare function, we derive conditions for a decreasing marginal tax rate throughout the skill distribution, a strictly concave tax function in income and a single-peaked average tax schedule. With additive preferences and a...

We study the responses of real and nominal prices to random flutuations in costs and money growth using a monetary search economy in which there are no costs or temporal restrictions on sellers' ability to change prices. The economy exhibits a form of price stickiness in that the price level may...

This paper analyses the impact of labor market conditions on a firm's incentive to train its workers. In an equilibrium model of the labor market in which firms use both untrained and in-house trained workers, we show that the incidence of training increases with the tightness of the labor...

This paper was presented as the 2006 W.A. Mackintosh Lecture at Queen's University. I consider some of the leading arguments for assigning an important role to tracking the growth of monetary aggregates when making decisions about monetary policy. First, I consider whether ignoring money means...