DEALING WITH UNCERTAINTY: ROBUST RULES IN MONETARY POLICY

We argue that in seeking to insure against model uncertainty, monetary policy makers are often ready to trade ex post performance for greater certainty in the outcome. They thus look for rules that although not optimal ex post, have certain properties that qualify them as robust. We apply first, Gul's approach of ‘disappointment’ aversion to describe policy makers' aversion to uncertainty and then define the properties the notion of ‘robustness’ entails. With these two tools we then link the desirability of such robust rules to the degree of policy makers' aversion to uncertainty. We thus show that provided such robust rules exist, a larger degree of disappointment aversion leads to a greater emphasis on robustness in policy implementation.     

Monetary policy and heterogeneous expectations

This paper studies the implications for monetary policy of heterogeneous expectations in a New Keynesian model. The assumption of rational expectations is replaced with parsimonious forecasting models where agents select between predictors that are underparameterized. In a Misspecification Equilibrium agents only select the best-performing statistical models. We demonstrate that, even when monetary policy rules satisfy the Taylor principle by adjusting nominal interest rates more than one for one with inflation, there may exist equilibria with Intrinsic Heterogeneity. Under certain conditions, there may exist multiple misspecification equilibria. We show that these findings have important implications for business cycle dynamics and for the design of monetary policy.     

Robust monetary policy under model uncertainty and inflation persistence

In this paper, we examine the inflation persistence puzzle by applying the robust control approach of Hansen and Sargent (2008). In line with the literature suggesting that inflation persistence may be affected by the monetary policy design and its institutional characteristics, we find that inflation persistence is positively related to the central bank's preference for model robustness. In effect, model uncertainty and robust decision making may be considered as a mechanism generating inflation persistence, for a given non-zero degree of autocorrelation in supply-side shocks. Further, the policy implication is that the central bank's monetary policy under model uncertainty renders, in terms of the sacrifice ratio, the output-cost of inflation stabilization more important.     

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     

Government policy and the probability of coordination failures

This paper introduces an approach to the study of optimal government policy in economies characterized by a coordination problem and multiple equilibria. Such models are often criticized as not being useful for policy analysis because they fail to assign a unique prediction to each possible policy choice. We employ a selection mechanism that assigns, ex ante, a probability to each equilibrium indicating how likely it is to obtain. We show how such a mechanism can be derived as the natural result of an adaptive learning process. This approach leads to a well-defined optimal policy problem, and has important implications for the conduct of government policy. We illustrate these implications using a simple model of technology adoption under network externalities.     

Avoiding Nash inflation: Bayesian and robust responses to model uncertainty

We examine learning, model misspecification, and robust policy responses to misspecification in a quasi-real-time environment. The laboratory for the analysis is the Sargent [The Conquest of American Inflation, Princeton Univ. Press, Princeton, NJ, 1999] explanation for the origins of inflation in the 1970s and the subsequent disinflation. Three robust policy rules are derived that differ according to the extent that misspecification is taken as a parametric phenomenon. These responses to drifting estimated parameters and apparent misspecification are compared to the certainty-equivalent case studied by Sargent. We find gains from utilizing robust approaches to monetary policy design, but only when the approach to robustness is carefully tailored to the problem at hand. In the least parametric approach, the medicine of robust control turns out to be too potent for the disease of misspecification. In the most parametric approach, the response to misspecification is too weak and too misdirected to be of help. But when the robust approach to policy is narrowly directed in the correct location, it can avoid Nash inflation and improve social welfare. It follows that agnosticism regarding the sources of misspecification has its pitfalls. We also find that Sargent's story for the rise of inflation of the 1970s and its subsequent decline in the 1980s is robust to most ways of relaxing a strong assumption in the original work.     

Price‐level versus inflation targeting under model uncertainty

It has recently been suggested that price‐level targeting (PLT) may be a superior approach to monetary policy than inflation targeting (IT) due to its ability to automatically influence inflation expectations to stabilize the economy. In this paper, I analyze whether PLT dominates IT if the ability of the central bank to influence expectations is limited by model uncertainty. Specifically, I analyze how the characterization and performance of PLT and IT rules are impacted if private agents form expectations according to a model that deviates from the policy‐maker's reference model. Using robust control to derive robust rules in such a situation, I find that the performance of PLT rules deteriorate faster than that of IT rules as the degree of misspecification increases. Nevertheless, the absolute decline in performance of the PLT rules is relatively small across alternative models that are statistically plausible.     

Educational policy and the economics of the family

This paper analyzes the implications of alternative ways to model decision-making by families for educational policy. We show that many of the policy implications associated with credit constraints cannot be distinguished from the implications of models of the family that differ from the conventional Barro-Becker model. We then argue that it is the combination of credit constraints and non-conventional preferences that provides a robust basis for government intervention to promote educational investment.     

Robust control and model misspecification

A decision maker fears that data are generated by a statistical perturbation of an approximating model that is either a controlled diffusion or a controlled measure over continuous functions of time. A perturbation is constrained in terms of its relative entropy. Several different two-player zero-sum games that yield robust decision rules are related to one another, to the max-min expected utility theory of Gilboa and Schmeidler [Maxmin expected utility with non-unique prior, J. Math. Econ. 18 (1989) 141-153], and to the recursive risk-sensitivity criterion described in discrete time by Hansen and Sargent [Discounted linear exponential quadratic Gaussian control, IEEE Trans. Automat. Control 40 (5) (1995) 968-971]. To represent perturbed models, we use martingales on the probability space associated with the approximating model. Alternative sequential and nonsequential versions of robust control theory imply identical robust decision rules that are dynamically consistent in a useful sense.     

Unconditionally optimal Ramsey policy

We discuss a time invariant policy which delivers the unconditionally optimal outcomes in purely forward-looking models and Ramsey outcomes in purely backward-looking models. This policy is a product of interaction between two institutions with distinct responsibilities. Motivated by Brendon and Ellison (2015), we think of them as arms of government. One institution is responsible for ‘forward guidance’, setting rules which are necessary and sufficient to determine private expectations. The second institution implements optimal policy taking expectations as given. The forward guidance rules are designed to maximise the unconditional expectation of the social objectives.     

MISPERCEPTIONS AND MONETARY POLICY IN A NEW-KEYNESIAN MODEL

This paper studies the consequences for the monetary policy design of information shortages on the part of the private sector. We model these shortages as exogenous shocks to expected income, which through an IS curve, disturb aggregate demand. We constrain policymakers to follow Taylor‐like rules but allow them to optimise coefficients: we find that the presence of misperceptions makes the optimised Taylor rule respond more aggressively to inflation and the output gap. We also find that if the policymaker is uncertain about misperceptions, then it is less costly to assume they are pervasive when they are not than the reverse. In other words, setting policy on the basis that the private sector is subject to misperceptions is a ‘robust’ policy.     

Bernanke versus Taylor: a post mortem

Our analysis sheds light on the issue of whether the monetary policy contributed to the recent housing boom and bust. We have estimated and analysed a model that allows a comparison between the actual policy and several alternative Taylor rules. When the Taylor rule path was computed using revised data and the deflator for the GDP, we found a notable impact on key housing market variables, supporting Taylor’s critique of the Fed policy. However, the bulk of our evidence suggests that the policy as it would have been conducted under our real-time Taylor rules would not have had any significant impact on the housing market variables. This conclusion is robust with regard to the price index used as well as the relative weights used on the inflation and output gaps.     

Fiscal policy rules,budget deficits,and forecasting biases

In this paper, we analyze the impact fiscal policy rules have on budget deficits and forecasting biases in official budget outlooks. Persistent budget deficits and over-optimistic budget forecasts have been observed in many countries in the past, especially in the euro area. To prevent such developments from happening in the future, fiscal rules have been revised or implemented with the aim to strengthen both preventive (ex-ante) and corrective (ex-post) elements of fiscal rules frameworks. Do such ex-ante and ex-post rules differ in their effects? In an attempt to answer this question, we build a two-period model and distinguish between ex-ante rules that apply to budget forecasts and ex-post rules that apply to realized budget deficits. Our model indicates that effectively enforced ex-post rules are more effective than ex-ante rules at reducing budget deficits. Interestingly, ex-ante rules differ from ex-post rules in their effects on forecasting biases. Only ex-post sanctions reduce forecasting biases, while ex-ante rules have no impact on such biases. In addition, we show that political stability and the size of government increase the effectiveness of fiscal rules. If, however, financial markets have a disciplining effect on governments, the effectiveness of fiscal rules is reduced. Our results imply that if fiscal policy rules cannot be effectively enforced, reforming other areas such as electoral rules or financial market regulations might be a more promising approach to ensuring sound public finances than fiscal policy rules.     

Supply and demand biases in linear interindustry models

We explore the sectoral and aggregate implications of some endogeneization rules (i.e. on value-added and final demand) which have been common in the extended demand-driven Leontief model and have been recently proposed in the supply-driven Ghosh model. Extended linear models are refinements that aim at endowing the linear models with additional general equilibrium feedbacks. We detect that these rules may give rise in these models to some allegedly pathological and biased behavior. We find that in these models sectoral or aggregate output may not follow the logical and economically expected direct relationship with some underlying endogenous variables — namely, output and value-added in the supply-driven model and output and consumption in the demand-driven model. Because of their shared mathematical structure, whatever is or seems to be pathological in the Ghosh model also has a symmetric counterpart in the Leontief model. These would not be good news for the inner consistency of these linear models and raise doubts regarding the validity of their empirical applications. To avoid such possible inconsistencies, we propose new and simple endogeneization rules that have a sound economic interpretation.     

Monetary Regime Choice and Optimal Credit Rationing at the Official Rate: The Case of Russia

ABSTRACT

Stabilizing monetary policy in a small open economy is constrained by the open economy trilemma. In this paper, we investigate whether foreign exchange market interventions and the Central Bank’s credit rationing at the official rate (CROR) may soften this constraint and improve the results of monetary policy for different monetary regimes. We construct a dynamic stochastic general equilibrium (DSGE) model appropriate for analyzing the forward-looking behavior of households facing non-zero probabilities of losing access to financial market and CROR. We have found significant credit rationing in the quarterly Russian data of 2001:Q1–2014:Q2. The probability of losing access to financial market and the probability of CROR are estimated as 22% and 66%, respectively. Using Russian data of 2001:Q1–2014:Q2 we demonstrate that CROR provoked forward-looking activity in financial market, which led to more Ruble devaluation in the crises of 2008–2009. It improved poor countercyclical performance of two Russian monetary policy rules, whereas made small effect on welfare. Welfare maximization exercises reveal a tradeoff between low-inflation and high-welfare solutions and favor of a floating exchange rate regime. We found the optimal value of the probability of CROR in both exchange rate-based and Taylor rule-based models but resulting improvement in welfare is very small.     

Remittances and GDP in Jamaica: An ARDL Bounds Testing Approach to Cointegration

Similar to other developing nations, Jamaica’s remittances, specifically inflows, are an important source of income support and foreign exchange earnings. Anecdotally, much has been said about the relationship between remittances and GDP in this country. Yet, less has been established using rigorous statistical inference. We test for unit roots with structural breaks and use the autoregressive distributed lag (ARDL) approach to cointegration to help fill this lacuna in the literature on Jamaica. Using annual data for the 1976–2014 period, we examine the relationship between GDP and remittances, both measured in constant 2010 US dollar terms, as we control for the common determinants of economic growth. The main finding is that GDP and remittances are cointegrated relationship wherein they both reinforce each other positively. This finding is statistically robust as the ARDL models have well-behaved errors and parameters that are generally stable over the period. We discuss policy implications of this finding.     

Evaluating the effect of monetary policy on unemployment with alternative inflation forecasts

This paper explores the role that inflation forecasts play in the uncertainty surrounding the estimated effects of alternative monetary rules on unemployment dynamics in the euro area and the US. We use the inflation forecasts of 8 competing models in a standard Bayesian VAR to analyse the size and the timing of these effects, as well as to quantify the uncertainty relative to the different inflation models under two rules. The results suggest that model uncertainty can be a serious issue and strengthen the case for a policy strategy that takes into account several sources of information. We find that combining inflation forecasts from many models not only yields more accurate forecasts than those of any specific model, but also reduces the uncertainty associated with the real effects of policy decisions. These results are in line with the model-combination approach that central banks already follow when conceiving their strategy.     

How relevant are nominal contracting schemes for monetary policy?

Due to the scarcity of pertinent evidence, there is currently no general agreement on how to introduce nominal rigidities into monetary macroeconomic models. We examine the role of alternative assumptions about the wage and price setting mechanisms for the assessment of the welfare costs of nominal rigidities and the performance of alternative monetary policy rules in an otherwise standard New Keynesian general equilibrium model. We find that the choice of a particular price and wage setting scheme matters quantitatively for the welfare costs of nominal rigidities. However, the ranking of the welfare costs associated with alternative wage and price setting schemes is robust to changes in the monetary policy rule, and the ranking of the welfare costs associated with alternative monetary policy rules is robust to changes in the wage and price setting scheme. The difference between sticky nominal contracts and sticky information matters more than the difference in the age distribution of prices wages and information implied by alternative price and wage setting schemes.     

Asymmetric monetary policy rules for the euro area and the US

We analyse the implications of asymmetric monetary policy rules by estimating Markov-switching DSGE models for the euro area (EA) and the US. The estimations show that until mid-2014 the ECB’s response to inflation was more forceful when inflation was above than below the central bank’s aim. Since then, the ECB’s policy can be characterised as symmetric, and we quantify the macroeconomic implications of this policy change. We uncover asymmetries also in the Fed’s policy, which has responded more strongly in times of crisis. We compute optimal simple rules for the EA and the US in an environment with the effective lower bound and a low neutral real rate, and find that it prescribes a stronger response to inflation and the output gap when inflation is below target compared to when it is above target. We document its stabilisation properties had this optimal rule been implemented over the last two decades.     

Macroeconomic implications of modeling the Internal Revenue Code in a heterogeneous-agent framework

Tax policy analysis in heterogeneous-agent models typically involves the use of smooth tax functions to approximate complex present tax law and proposed reforms. In this paper, we explore the extent to which the tax detail omitted under this conventional approach has macroeconomic implications relevant for policy analysis. To do this, we develop an alternative approach by embedding an internal tax calculator into a large-scale overlapping generations model that, while conditioning on idiosyncratic household characteristics, explicitly models key provisions in the Internal Revenue Code applied to labor income. We find that for a debt-constant steady state analysis of a given tax policy change, both approaches generate similar policy-induced patterns of macroeconomic activity despite variation in the underlying patterns of household tax-preferred consumption and labor supply behavior. However, this variation in underlying behavior is associated with significant quantitative and qualitative differences in macroeconomic aggregates along a debt-financed transition path immediately following a policy change. Consequentially, although the use of unconditional smooth tax functions may be a reasonable modeling simplification for steady state analysis of tax policy, caution should be taken for their use in transition path analysis within heterogeneous-agent models.