This paper proposes a framework of endogenous energy production with convex costs to investigate the general equilibrium effects of energy price shocks on the business cycle. This framework explicitly models the consumption of durables and nondurables and implements a high complementarity between energy and the usage of durables and capital. The model predicts energy price elasticities of various consumption variables that fall within reasonable agreement with empirical estimates. Convex costs in energy production produce energy price and energy supply dynamics that tallies well with empirical behavior. Our analysis confirms in a theoretical setting recent observations that not all energy price shocks are the same. They can be distinct in terms of energy price dynamics and impact on the business cycle, as well as energy price elasticities of various macro variables that can be useful indicators for their underlying causes.

This paper argues that trade specialization played an indispensable role in supporting the Industrial Revolution. We calibrate a two-good and two-sector overlapping generations model for England's historical development and investigate how much different England's development path would have been if it had not globalized in 1840. The open-economy model is able to match the data closely, but the closed-economy model cannot explain the fall in the value of land relative to wages observed in the nineteenth century. Without globalization, the transition period in the British economy would have been considerably longer than that observed in the data and key variables, such as the share of labor force in agriculture, would have converged to figures very distant from the actual ones.

We characterize the necessary and sufficient conditions for optimality in discrete-time, infinite-horizon optimization problems with a state space of finite or infinite dimension. It is well known that the challenging task in this problem is to prove the necessity of the transversality condition. To do this, we follow a duality approach in an abstract linear space. Our proof resembles that of Kamihigashi (2003), but does not explicitly use results from real analysis. As an application, we formalize Sims's argument that the no-Ponzi constraint on the government budget follows from the necessity of the tranversality condition for optimal consumption.

We apply the business cycle accounting methodology proposed by Chari, Kehoe, and McGrattan to identify the sources of Spanish business fluctuations during two outstanding cyclical episodes: the recession alongside the transition to democracy in 1977 and the great recession of 2008. We find that the labor wedge played a key role during both recessions and that taxes and labor market institutions are likely behind the wedge movements. We conclude that any model that tries to understand the causes of recessions that occurred in the last three decades should focus on the labor wedge.

We use an overlapping-generations model with endogenous retirement and saving to study the trade-off between saving and retirement age in response to mortality decline. When life expectancy increases by one year, people delay retirement by about four months. With this magnitude of delay in retirement age, the percentage of lifetime spent in working decreases, and people have to save more for postretirement years. Neither the pure form of sole adjustment through savings nor the proportionality hypothesis is consistent with our results, but the proportionality hypothesis is a better rule of thumb in predicting future behavior. Our choice of the modified Boucekkine et al. (2002) survival function gives a convenient one-to-one correspondence between life expectancy increase and a change in the survival parameter.

Because they ignore the household-level and macroeconomic adjustments associated with longevity improvements, the actuarial projections of the Social Security Administration overestimate the Social Security crisis. Using a general-equilibrium model with heterogeneous households and incomplete markets, I show that with these adjustments accounted for, a significantly smaller decline in benefits is needed to balance the Social Security budget. Households respond by delaying retirement and Social Security benefit collection, by working more hours, and by also saving more. In general equilibrium, these effects lead to a natural expansion of Social Security's tax base and generate significant delayed retirement credits, which the actuarial estimates completely overlook.

In this paper, we investigate real-time behavior of constant-gain stochastic gradient (SG) learning, using the Phelps model of monetary policy as a testing ground. We find that whereas the self-confirming equilibrium is stable under the mean dynamics in a very large region, real-time learning diverges for all but the very smallest gain values. We employ a stochastic Lyapunov function approach to demonstrate that the SG mean dynamics is easily destabilized by the noise associated with real-time learning, because its Jacobian contains stable but very small eigenvalues. We also express caution on usage of perpetual learning algorithms with such small eigenvalues, as the real-time dynamics might diverge from the equilibrium that is stable under the mean dynamics.

We revisit the sources of the bias in Federal Reserve forecasts and assess whether a precautionary motive can explain the forecast bias. In contrast to the existing literature, we use forecasts submitted by individual Federal Open Market Committee (FOMC) members to uncover members' implicit loss function. Our key finding is that the loss function of FOMC members is asymmetric: FOMC members incur a higher loss when they underpredict (overpredict) inflation and unemployment (nominal and real growth) as compared to their making an overprediction (underprediction) of similar size. We also find that an asymmetric loss function, in some cases, weakens evidence against forecast rationality, though results depend on the variable being projected and the subgroup of FOMC members being studied. Furthermore, we add to the recent controversy on the relative quality of FOMC forecasts compared to staff forecasts. Our results suggest that differences in predictive ability could indeed stem from differences in preferences.

We analyze a general R&D-based endogenous growth model with a growth-essential natural resource. The economy comprises two separate sectors, final output and R&D, both directly or indirectly dependent on the natural resource. Because the resource is exhaustible and it is an essential productive input, increasing returns to scale to manmade inputs are compatible with nonexplosive sustained growth. The instability problem usually associated with increasing returns is overcome thanks to the existence of imperfect markets in a decentralized economy. We find an admissible range of values for the elasticity of capital in the R&D sector under which growth is fully endogenous and saddlepath stable, with no need of exogenous population growth.

Much empirical evidence finds that governments react to fiscal imbalances in a nonlinear way, through an increasing marginal response of primary surpluses to changes in debt. This paper shows that nonlinear fiscal regimes alter equilibria under active and passive monetary–fiscal policies. The Fisher equation combined with nonlinear fiscal policies leads to multiple steady states. Under passive interest rate rules, even if the steady state in which fiscal policy is active is locally saddlepath stable, there exist infinite equilibrium paths originating in the neighborhood of that steady state that converge into a high-debt trap. Under active interest rate rules, even if the steady state at which fiscal policy is active is locally unstable, there exists a saddle connection with the high-debt equilibrium along which inflation is uniquely determined.

This paper introduces imperfect knowledge and learning behavior of economic agents into the Kiyotaki and Moore model and studies the interaction of agents' collateral price beliefs, collateral constraint, and aggregate economic activity over the business cycle. It establishes the E-stability condition and the convergence of the real time learning process. In addition, it shows that learning strengthens the role of collateral constraints in aggregate fluctuations.