I explore the welfare implications of currency union (CU) membership in a model that generates a trade-off between alternative monetary arrangements. While national currencies support country-specific monetary policies, a CU eliminates some barriers to trade and transitory cross-border price misalignments caused by nominal rigidities. I quantify the welfare gap between these two arrangements and show that it depends crucially on the correlation of shocks across the countries involved. I estimate the model with data from 11 Eurozone members and I seek the minimum trade gains needed to make a single currency worthwhile for them. I find that modest trade gains are likely to be sufficient, given the good business-cycle affiliation of these economies.

We compare model forecast error statistics with forecast error statistics of professional forecasts. We look at a standard sticky-prices–wages model, concluding that it delivers too strong a theoretical forecastability of the variables under scrutiny, at odds with the data (professional forecasts). We argue that the lack of compatibility between the model and professional forecasts results from trying to fit inflation (which is probably nonstationary) to a model that assumes inflation is stationary. A modified version of the model, one with a varying inflation target, delivers a better fit in terms of forecastability.

Habit formation is a fixture of contemporary new Keynesian models. The vast majority assume that agents form habits strictly over consumption of an aggregate good, leaving open the question of whether it might be preferable to have them form habits over differentiated products instead–an arrangement known as deep habits. I answer this question by estimating a model that nests both habit concepts as special cases. Estimates reveal that the data favor a specification in which consumption habits are stronger at the product level than at the aggregate level. A mix of significance tests and simulation results indicate that including deep habits greatly improves model fit, most notably with regard to inflation dynamics.

In this paper we study the transmission of capital depreciation shocks. The existing literature in the real business cycle tradition has concluded that these shocks are irrelevant to business cycle fluctuations. We show that they are potentially important drivers of aggregate fluctuations in a new Keynesian model. Nominal rigidities and some persistence in the shock process are the key ingredients that generate co-movement across real variables.

We argue that a fixed exchange rate can be an optimal choice even if a policy maker could commit to the first-best monetary policy whenever the private sector's beliefs reflect incomplete information about the policy maker's dependability. This model implies that joining a currency area may be optimal for its impact not on the behavior of the policy maker, but on the beliefs of the private sector. Monetary policies are evaluated using a new Keynesian model of a small open economy solved under imperfect policy credibility. We quantify the minimum distance between announced policy and the private sector's beliefs that is necessary for a peg to perform better than an independent monetary policy when the policy maker can commit to the first-best policy.

This paper shows that the optimal monetary policies recommended by New Keynesian models still imply a large amount of inflation risk. We calculate the term structure of inflation uncertainty in New Keynesian models when the monetary authority adopts the optimal policy. When the monetary policy rules are modified to include some weight on a price path, the economy achieves equilibria with substantially lower long-run inflation risk. With either sticky prices or sticky wages, a price path target reduces the variance of inflation by an order of magnitude more than it increases the variability of the output gap.

Recent literature on the design of optimal monetary policy has shown that deviations from price stability are small whenever prices are sticky. This paper reconsiders this issue by introducing capital accumulation in the model. Optimal monetary policy in this setup implies small deviations from price stability. The monetary authority optimally uses inflation as an explicit tax on monopolistic profits to reduce the price markup across states. Variable markup is achieved in this setup because the share of investment demand over output varies across states and in response to TFP shocks.

We study a structural dynamic monetary economy submitted to technological, monetary, and real demand shocks, and investigate the nature of optimal monetary and fiscal policies under Walrasian or preset wages and prices. If prices and wages are Walrasian, then the optimal policies are both nonactivist and derive directly from Milton Friedman's prescriptions. If prices or wages are preset, however, optimal policies, and, notably, the fiscal part, become activist and countercyclical.