We implement optimal economic outcomes at the lowest social cost by combining reputation and contracting mechanisms to overcome the time-inconsistency problem of monetary policy associated with an inflation bias. We characterize the conditions under which the reputation force alone induces a central bank to behave in a socially optimal way. When these conditions fail, an incentive contract is invoked, whose cost is significantly reduced by the presence of the reputation force. The contract poses a penalty threat that is a concave function of wage growth, which in equilibrium is tied to expected rather than realized inflation, with a global maximum that provides the least upper bound on all threatened penalties. This bound can be used as a uniform penalty threat to achieve optimal economic outcomes and still, for moderate to large shocks, its magnitude can be much smaller than the size of the transfers required by the standard contracts that are linear functions of realized inflation rates. Further, under both the concave and the uniform penalty threats, the central bank will behave in the socially optimal way and no transfer is materialized in equilibrium. Thus our hybrid mechanism solves the time-inconsistency problem while leaving the central bank with complete discretion to respond to new circumstances, without any reputation cost or penalty threatened by the contract actually invoked along the equilibrium path.

This article presents a solution algorithm for linear rational expectation models under imperfect information, in which some decisions are made based on smaller information sets than others. In our solution representation, imperfect information does not affect the coefficients on crawling variables, which implies that, if a perfect-information model exhibits saddle-path stability, for example, the corresponding imperfect-information models also exhibit saddle-path stability. However, imperfect information can significantly alter the quantitative properties of a model. Indeed, this article demonstrates that, with a predetermined wage contract, the standard RBC model remarkably improves the correlation between labor productivity and output.

This article analyzes an economy where both nonrenewable resources and a costly energy resource are essential inputs in production. The extraction of the nonrenewable resources leads to emissions that increase the probability of a catastrophe. We find that, in contrast to the constant-probability case, the endogenous probability of a catastrophe implies that some nonrenewable resources might optimally be left in the ground. The larger the effect of the fossil energy use on the probability of a catastrophe, the fewer nonrenewable resources should be extracted and the earlier should be the switch to the renewable substitute. The richer a country, the earlier it should shift to the energy substitute. In the trade-off between higher consumption and a higher probability of catastrophe, even small probability changes are likely to be more important for the planner than higher consumption.

This paper proposes the use of wavelet methods to estimate U.S. core inflation. It explains wavelet methods and suggests that they are ideally suited to this task. Comparisons are made with traditional Consumer Price Index–based and regression-based measures for their performance in following trend inflation and predicting future inflation. Results suggest that wavelet-based measures perform better, and sometimes much better, than the traditional approaches. These results suggest that wavelet methods are a promising avenue for future research on core inflation.

The next international version of the System of National Accounts will recommend that R&D (Research and Development) expenditures be capitalized instead of being immediately expensed as in the present System of National Accounts 1993. An R&D project creates a new technology, which in principle does not depreciate like a reproducible asset. A new technology is, however, subject to obsolescence, which acts in a manner that is somewhat similar to depreciation. The paper looks at the net benefits of an R&D project in the context of a very simple intertemporal general equilibrium model and suggests that R&D expenditures be amortized using the matching principle that has been developed in the accounting literature to match the fixed costs of a project to a stream of future benefits. Of particular interest is the evaluation of the net benefits of a publicly funded project where the results are made freely available to the public.

We study a generic optimal control problem with a stock that accumulates with constant delay. We show that the optimal system dynamics reduces to a system of ordinary differential equations, implying monotonic optimal paths, if the objective function is additively separable in the stock and the control. This is, however, not true for general objective functions, which may exhibit nonmonotonic and oscillatory optimal paths. The reason is that the impact of the stock on the objective depends on the current level of the control, whereas the control influences the dynamics of the stock with a delay.

We develop an overlapping-generations model for a closed economy with uncertainty on labor income and mortality risk to show that unfunded social security programs may increase welfare in economies where agents are affected by self-control problems à la Gul and Pesendorfer (2001, Econometrica 69, 1403). We depart from the existing literature by setting the agent's preference parameters to match target levels of macro-variables observed in the real U.S. economy. In our approach, economies with tempted and nontempted agents are indistinguishable in terms of aggregate consumption, labor, and saving behavior when social security provides a replacement rate of 40% (as in the United States). This situation makes agents bear costly self-control problems over more years. Our simulations indicate that social security improves welfare with degrees of temptation equal to 11% or higher. A social security program with a replacement rate of 40% finds support for degrees of temptation not lower than 15%.