Monetary policy with uncertain parameters

In a simple dynamic macroeconomic model, it is shown that uncertainty about structural parameters does not necessarily lead to more cautious monetary policy, refining the accepted wisdom concerning the effects of parameter uncertainty on optimal policy. In particular, when there is uncertainty about the persistence of inflation, it may be optimal for the central bank to respond more aggressively to shocks than under certainty equivalence, since the central bank this way reduces uncertainty about the future development of inflation. Uncertainty about other parameters, in contrast, acts to dampen the policy response. JEL Classification: E43, E52

Robust monetary policy in the New-Keynesian framework

We study the effects of model uncertainty in a simple New-Keynesian model using robust control techniques. Due to the simple model structure, we are able to find closed-form solutions for the robust control problem, analysing both instrument rules and targeting rules under different timing assumptions. In all cases but one, an increased preference for robustness makes monetary policy respond more aggressively to cost shocks but leaves the response to demand shocks unchanged. As a consequence, inflation is less volatile and output is more volatile than under a non-robust policy. Under one particular timing assumption, however, increasing the preference for robustness has no effect on the optimal targeting rule (nor on the economy).Knightian uncertainty; model uncertainty; robust control; min-max policies

Robust monetary policy in a small open economy

This paper studies how a central bank’s preference for robustness against model misspecification affects the design of monetary policy in a New-Keynesian model of a small open economy. Due to the simple model structure, we are able to solve analytically solve the optimal robust policy rule, and separately ana-lyze the effects of robustness against misspecification concerning the determination of inflation, output and the exchange rate. We show that an increased central bank preference for robustness makes monetary policy respond more aggressively or more cautiously to shocks, depending on the type of shock and the source of misspecification.Knightian uncertainty; model uncertainty; robust control; min-max policies

Robust monetary policy in the New-Keynesian framework

We study the effects of model uncertainty in a simple New-Keynesian model using robust control techniques. Due to the simple model structure, we are able to find closed-form solutions for the robust control problem, analysing both instrument rules and targeting rules under different timing assumptions. In all cases but one, an increased preference for robustness makes monetary policy respond more aggressively to cost shocks but leaves the response to demand shocks unchanged. As a consequence, inflation is less volatile and output is more volatile than under a non-robust policy. Under one particular timing assumption, however, increasing the preference for robustness has no effect on the optimal targeting rule (nor on the economy).Knightian uncertainty, model uncertainty, robust control, min- max policies

Re-Evaluating Swedish Membership in EMU: Evidence from an Estimated Model

I revisit the potential costs and benefits for Sweden of joining the Economic and Monetary Union (EMU) of the European Union. I first show that the Swedish business cycle since the mid-1990s has been closely correlated with the Euro area economies, suggesting that common shocks have been an important driving force of business cycles in Europe. However, evidence from an estimated model of the Swedish economy instead suggests that country-specific shocks have been important for fluctuations in the Swedish economy since 1993, implying that EMU membership could be costly. The model also indicates that the exchange rate has to a large extent acted to destabilize, rather than stabilize, the Swedish economy, pointing to the costs of independent monetary policy with a flexible exchange rate. Finally, counterfactual simulations of the model suggest that Swedish inflation and GDP growth might have been slightly higher if Sweden had been a member of EMU since the launch in 1999, but also that GDP growth might have been more volatile. The evidence is therefore not conclusive about whether or not participation in the monetary union would be advantageous for Sweden.

New-Keynesian Models and Monetary Policy: A Reexamination of the Stylized Facts

Using an empirical New-Keynesian model with optimal discretionary monetary policy, we calibrate key parameters - the central bank's preference parameters; the degree of forward-looking behavior in the determination of inflation and output; and the variances of inflation and output shocks - to match some broad characteristics of U.S. data. Our preferred parameterizations all imply a small concern for output stability but a large preference for interest rate smoothing, and a small degree of forward-looking behavior in price-setting but a large degree of forward-looking in the determination of output. We provide some intuition for these results and discuss their consequences for practical monetary policy analysis.Interest rate smoothing; central bank objectives; forward-looking behavior

Monetary policy in a small open economy with a preference for robustness

We use robust control techniques to study the effects of model uncertainty on monetary policy in an estimated, semi-structural, small-open-economy model of the U.K. Compared to the closed economy, the presence of an exchange rate channel for monetary policy not only produces new trade-offs for monetary policy, but it also introduces an additional source of specification errors. We find that exchange rate shocks are an important contributor to volatility in the model, and that the exchange rate equation is particularly vulnerable to model misspecification, along with the equation for domestic inflation. However, when policy is set with discretion, the cost of insuring against model misspecification appears reasonably small.Monetary policy

Methods for robust control

Robust control allows policymakers to formulate policies that guard against model misspecification. The principal tools used to solve robust control problems are state-space methods (see Hansen and Sargent 2006 and Giordani and Soderlind 2004). In this paper we show that the structural-form methods developed by Dennis (2006) to solve control problems with rational expectations can also be applied to robust control problems, with the advantage that they bypass the task, often onerous, of having to express the reference model in statespace form. Interestingly, because state-space forms and structural forms are not unique the two approaches do not necessarily return the same equilibria for robust control problems. We apply both state-space and structural solution methods to an empirical New Keynesian business cycle model and find that the differences between the methods are both qualitatively and quantitatively important. In particular, with the structural-form solution methods the specification errors generally involve changes to the conditional variances in addition to the conditional means of the shock processes.Robust control ; Monetary policy ; Econometric models

Spo0J and SMC are required for normal chromosome segregation in Staphylococcus aureus

Bacterial chromosome segregation is an essential cellular process that is particularly elusive in spherical bacteria such as the opportunistic human pathogen Staphylococcus aureus. In this study, we examined the functional significance of a ParB homologue, Spo0J, in staphylococcal chromosome segregation and investigated the role of the structural maintenance of chromosomes (SMC) bacterial condensin in this process. We show that neither spo0J nor smc is essential in S. aureus; however, their absence causes abnormal chromosome segregation. We demonstrate that formation of complexes containing Spo0J and SMC is required for efficient S. aureus chromosome segregation and that SMC localization is dependent on Spo0J. Furthermore, we found that cell division and cell cycle progression are unaffected by the absence of spo0J or smc. Our results verify the role of Spo0J and SMC in ensuring accurate staphylococcal chromosome segregation and also imply functional redundancy or the involvement of additional mechanisms that might contribute to faithful chromosome inheritance