Probability models and robust policy rules

We consider Sims's (2008) argument that robust policy making requires that policy models be treated as “probability models”. In a welfare-based setting, we estimate by Bayesian methods a number of variants of a New Keynesian macroeconomic model and use both the model odds and posterior densities to design robust interest rate rules consisting of an inflation-forecast-based rule and a wage-targeting one. Each are shown to have distinct robustness qualities and distinct implications for the probability-models approach. To ensure feasible policy, we further impose that rules are stable, determinate and lower-bound compatible. Our results have important implications for the design, evaluation and analysis of the probability models approach to robust monetary policy making.     

Optimal versus realized policy rules in a regime-switching framework

In this paper we compare a deterministic model and a Markov switching model to analyze the behavior of the US economy and the Federal Reserve. We examine both optimal and empirical monetary policies for the US Federal Reserve between 1960 and 2008. We compare the optimal monetary policy to the actual interest rates and to the empirical reaction function. We also evaluate the sensitivity of the results to the preferences assigned to each objective. We find that there is no unique optimal solution that fits the Federal Reserve behavior over the entire period. The best fit to the actual interest rates is obtained by an optimal policy with preference switches following the rule: a high-volatility regime coincides with a priority on inflation alone while in a low-volatility regime there is equal policy priority on output stabilization and inflation.     

Cost-benefit rules in general disequilibrium

The consequences of imbalances in markets for goods and factors are the prime issues in many project evaluations. This is so in evaluations of measures like migration, manpower training programmes and plant locations. In the present paper a general disequilibrium model of a small open economy is used to generate evaluation rules to be used when markets do not clear through price adjustments.     

Optimal simple rules for the conduct of monetary and fiscal policy

Stabilization policy involves joint monetary and fiscal rules. We develop a model enabling us to characterize systematic simple monetary and fiscal policy over the business cycle. We principally focus on the following question. What are the key properties of the joint simple rule governing the conduct of systematic stabilization policy? We find that conducting stabilization policy incorporates not only a set of monetary policy choices governed by the so-called ‘Taylor principle’ but also fiscal policy that gives considerable force to automatic stabilizers. Recent US and UK monetary and fiscal choices seem broadly consistent with this model. This result is found to be robust to a number of alternate modeling strategies.     

The neutrality of systematic monetary policy in models with a disequilibrium price level

A condition is offered which is necessary and sufficient for the neutrality of aggregate output and the real rate of interest with respect to systematic monetary policy in a general class of stochastic macroeconomic models with rational expectations, additive disturbances, lagged information and a disequilibrium price sequence.     

Electoral regime and trade policy

We study how trade protection varies with the electoral rules for legislative representation. In particular, we investigate different hypotheses about why trade policy differs between countries with legislatures elected by a plurality election rule in single member constituencies and legislatures elected by a proportional, or party-list, rule. Our results, which are in line with the existing literature, show that countries with list-PR systems tend to have lower trade barriers than countries with majoritarian systems. We expand on this literature by looking at the mechanisms through which this correlation can be explained. Our findings indicate that, contrary to existing theory, neither constituency size nor party strength are important when explaining this correlation. Country size does matter, but does not explain the whole of the correlation.     

Autocorrelated errors in simple disequilibrium models

The simple disequilibrium model is extended to the case in which the errors follow a first-order Markov process. This differs from the contribution of Laffont and Monfort in that sample partition is not assumed to be known. The likelihood function is derived and maximum likelihood estimates are obtained for the Rosen-Quandt model of an aggregate labor market.     

The performance and robustness of simple monetary policy rules in models of the Canadian economy

Abstract.  In this paper, we evaluate seven simple monetary policy rules in a wide range of models of the Canadian economy. Our results indicate that none of the seven simple policy rules we examined is robust to model uncertainty, in that no single rule performs well in all models. In fact, our results show that the performance of some of the simple rules, particularly rules with interest rate smoothing and rules with a high coefficient on the inflation gap, can substantially deviate from that of the optimal rule and can even be unstable in some models. Furthermore, we find that "open‐economy" rules do not perform well in many models. We find that adding an exchange rate term to a simple policy rule often increases the value of the policy‐maker's loss function. Although it is not robust, we find that a simple nominal Taylor‐type rule that has a coefficient of 2 on the inflation gap and 0.5 on the output gap outperforms the other simple rules in a certain class of models. However, even in those models, the loss‐function value of this simple rule can be substantially higher than that of the optimal or base‐case rule. JEL classification: E52, E58     

Bubble-free policy feedback rules

We consider a broad class of linear dynamic stochastic rational-expectations models made of a finite number N of structural equations for N+1 endogenous variables and to be closed by one policy feedback rule. We design, for any model of this class and any stationary VARMA solution of that model, a “bubble-free” policy feedback rule ensuring that this solution is not only the unique stationary solution of the closed model, but also its unique solution. We apply these results to locally linearisable models of the monetary transmission mechanism and obtain interest-rate rules that not only ensure the local determinacy of the targeted equilibrium in the neighbourhood of the steady state considered, but also prevent the economy from gradually leaving this neighbourhood.     

The financial accelerator and monetary policy rules

Comparing Bernanke et al.’s (1999) financial accelerator model to a comparable model without an operational financial accelerator mechanism, we find that financial acceleration is reduced when monetary policy reacts to the output gap and when firm-specific volatility rises.     

Volatility forecasting: long memory,regime switching and heteroscedasticity

In this article, we account for the first time for long memory, regime switching and the conditional time-varying volatility of volatility (heteroscedasticity) to model and forecast market volatility using the heterogeneous autoregressive model of realized volatility (HAR-RV) and its extensions. We present several interesting and notable findings. First, existing models exhibit significant nonlinearity and clustering, which provide empirical evidence on the benefit of introducing regime switching and heteroscedasticity. Second, out-of-sample results indicate that combining regime switching and heteroscedasticity can substantially improve predictive power from a statistical viewpoint. More specifically, our proposed models generally exhibit higher forecasting accuracy. Third, these results are widely consistent across a variety of robustness tests such as different forecasting windows, forecasting models, realized measures, and stock markets. Consequently, this study sheds new light on forecasting future volatility.     

Optimal manipulation rules in a mixed oligopoly

We study the optimal manipulation rules of a public firm’s objective function in a mixed oligopoly with imperfect product substitutability. We start with a baseline duopoly model and compare the solutions under quantity and price competition, and the way they are affected by product substitutability. This allows us to show that partial privatization, strategic delegation and other specific government’s commitments on the objective function of the public management can be looked at as special cases of these optimal rules, and to evaluate the viability of these policies under the two modes of competition. In this framework, we also discuss the equivalence between manipulation of the objective function and Stackelberg leadership. Since optimal manipulation rules change as new dimensions are added, we also derive the optimal rules under oligopoly, quadratic costs, and competition of international firms. This fairly general unified framework allows to discuss the impact of these factors on the government’s implementation policies of the optimal manipulation rules.     

Asset allocation under stochastic interest rate with regime switching

We investigate an optimal asset allocation problem in a Markovian regime-switching financial market with stochastic interest rate. The market has three investment opportunities, namely, a bank account, a share and a zero-coupon bond, where stochastic movements of the short rate and the share price are governed by a Markovian regime-switching Vasicek model and a Markovian regime-switching Geometric Brownian motion, respectively. We discuss the optimal asset allocation problem using the dynamic programming approach for stochastic optimal control and derive a regime-switching Hamilton–Jacobi–Bellman (HJB) equation. Particular attention is paid to the exponential utility case. Numerical and sensitivity analysis are provided for this case. The numerical results reveal that regime-switches described by a two-state Markov chain have significant impacts on the optimal investment strategies in the share and the bond. Furthermore, the market prices of risk in both the bond and share markets are crucial factors in determining the optimal investment strategies.     

Optimal fishery harvesting rules under uncertainty

This paper derives the optimal fishery harvest policy in a real-option model with a stochastic logistic growth process, harvest-sensitive output price, and both fixed and variable harvesting costs. The policy specifies the harvest trigger and harvest size, while outputs from the model include the value of the fishery and the risk of extinction. The optimal policy is illustrated with data from the Pacific Halibut Fishery. For this particular case, the optimal policy recommends harvesting when the fish stock rises to about three-quarters the environmental carrying capacity, and the amount harvested should be approximately a quarter of the prevailing stock. This harvesting policy maximizes the value of the fishery, and importantly, the resulting risk of extinction is negligible. We also carry out some sensitivity analysis to see how the optimal policy (and the resulting fishery value and risk of extinction) change when the input parameters are varied, particularly the ecological parameters intrinsic growth rate and volatility of the stock, and also the economic parameters that have been ignored in previous papers (price sensitivity and fixed cost). If the optimal policy is followed, the risk of extinction will be negligible, except for very low growth rate and high volatility.     

Optimal formation rules for patent pools

Patent pools in the framework of Lerner and Tirole (Am Econ Rev 94:691–711, 2004) may enhance or reduce social welfare. This paper presents a pool formation mechanism which prevents welfare decreasing pool equilibria to emerge, and which encourages welfare enhancing pools to form. In order to destabilize welfare decreasing pools, forcing coalitions members to offer individual licenses in parallel to the pool has been suggested. I show that in general, this mechanism is not an efficient antitrust tool. However, the mechanism combined with exclusive pool membership avoids stability problems of welfare enhancing pools, while it creates instability of welfare decreasing pools. I am grateful for comments from the Editor, an anonymous referee, and Georg von Graevenitz.     

Implementing optimal monetary policy: Objectives and rules

The inconsistency of optimal policy comes from inconsistency between the social loss function and the economic structure. Accordingly, this paper designs a central bank loss function, which proves consistent with the economic structure. Under the designed central bank loss function discretionary policy proves optimal for social welfare. Optimal discretionary policy emerges because the implied behavioral equation is identical with that under commitment to the social loss function. Consequently, this paper also designs policy rules. To some extent, policy rules appear more basic, flexible, and operational than social and central bank loss functions, but the social loss function serves as an ultimate objective and the central bank loss function explicitly identifies the attainable targets and appropriate weight to achieve the social optimum.     

Asymmetric expectation effects of regime shifts in monetary policy

This paper addresses two substantive issues: (1) Does the magnitude of the expectation effect of regime switching in monetary policy depend on a particular policy regime? (2) Under which regime is the expectation effect quantitatively important? Using two canonical DSGE models, we show that there exists asymmetry in the expectation effect across regimes. The expectation effect under the dovish policy regime is quantitatively more important than that under the hawkish regime. These results suggest that the possibility of regime shifts in monetary policy can have important effects on rational agents' expectation formation and on equilibrium dynamics. They offer a theoretical explanation for the empirical possibility that a policy shift from the dovish regime to the hawkish regime may not be the main source of substantial reductions in the volatilities of inflation and output.     

Optimal information acquisition and monetary policy

I study optimal monetary policy with an expectational AS curve and private agents who optimally choose their amount of information pertinent to predicting policy. Shocks with time-varying variance (ARCH) induce interesting information acquisition (IA) dynamics; optimal IA affects optimal policy and vice versa. Under discretion, IA dynamics cause time-varying effectiveness of policy because of the expectational AS curve; policy may be rendered completely ineffective. In policy game equilibrium, a fall in the shock’s variance typically induces less IA and raises welfare. In one exceptional case the opposite occurs, a result which does not require implausible unstable equilibria. An agent becoming informed increases the endogenous component of economic volatility; IA therefore has a negative externality. Under commitment policy’s effectiveness is again time-varying, but policy is never completely ineffective: commitment enables the central bank to credibly limit policy’s volatility; this limits private agents’ incentive to become informed, so limits expectation-induced policy neutrality.     

Optimal monetary policy and economic growth

A question at the center of many analyses of optimal monetary policy is, why do central banks never implement the Friedman rule? To the list of answers to this question, we add neoclassical production (specifically, the Tobin effect) as one possible explanation. To that end, we study an overlapping generations economy with capital where limited communication and stochastic relocation create an endogenous transactions role for fiat money. We assume a production function with a knowledge externality (Romer style) that nests economies with endogenous growth (AK form) and those with no long-run growth (the Diamond model). The Tobin effect is shown to be always operative. Under CRRA preferences, a mild degree of social increasing returns is sufficient (but not necessary) for some positive inflation to dominate zero inflation and for the Friedman rule to be sub-optimal, irrespective of the degree of risk aversion.