Central bank design with heterogeneous agents

We study alternative institutional arrangements for the determination of monetary policy in a general equilibrium model with heterogeneous agents, where monetary policy has redistributive effects. Inflation is determined by a policy board using either simple-majority voting, supermajority voting, or bargaining. We compare the equilibrium inflation rates to the first-best allocation.     

Serial dictatorship and Pareto optimality

In a deterministic allocation problem in which each agent is entitled to receive exactly one object, an allocation is Pareto optimal if and only if it is the outcome of a serial dictatorship. We extend the definition of serial dictatorship to settings in which some agents may be entitled to receive more than one object, and study the efficiency and uniqueness properties of the equilibrium allocations. We prove that subgame perfect equilibrium allocations of serial dictatorship games are not necessarily Pareto optimal; and generally not all Pareto optima can be implemented as subgame perfect equilibrium allocations of serial dictatorship games, except in the 2-agent separable preference case. Moreover, serial dictatorship games do not necessarily have unique subgame perfect equilibrium allocations, except in the 2-agent case, hence their outcomes are indeterminate and manipulable.     

Monetary policy, oil shocks, and TFP: Accounting for the decline in US volatility

An equilibrium model is used to assess the quantitative importance of monetary policy for the post-1984 decline in US inflation and output volatility. The principal finding is that monetary policy played a substantial role in reducing inflation volatility, but a small role in reducing real output volatility. The model attributes much of the decline in real output volatility to smaller TFP shocks. We also investigate the pattern of output and inflation volatility under an optimal monetary policy counterfactual. We find that real output volatility would have been somewhat lower, and inflation volatility substantially lower, had monetary policy been set optimally.     

On the non-neutrality and optimality of monetary policy when financial markets are incomplete: a macroeconomic perspective

We study in this paper a simple model of a two-period economy, with two states of the world in the second period, two agents and one good. Financial markets are incomplete since only inside money is available. We show that outside money, which is introduced in the model through its role as a medium of exchange, is non-neutral, in the sense that it has an effect on the equilibrium allocation. We then discuss whether a monetary policy that would aim at state-independent price levels is desirable. We illustrate that discussion with a few examples. The possible sub-optimality of a constant-across-states inflation rates target for monetary policy is to be contrasted with results from representative agent macroeconomic models.     

Information,trade and common knowledge

In any voluntary trading process, if agents have rational expectations, then it is common knowledge among them that the equilibrium trade is feasible and individually rational. This condition is used to show that when risk-averse traders begin at a Pareto optimal allocation (relative to their prior beliefs) and then receive private information (which disturbs the marginal conditions), they can still never agree to any non-null trade. On markets, information is revealed by price changes. An equilibrium with fully revealing price changes always exists, and even at other equilibria the information revealed by price changes “swamps” each trader's private information.     

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 control and central banking behaviour

This paper seeks to explain the recent behaviour of the two main central banks in the recent financial crisis, applying a robust control tool through a Neo-Keynesian monetary policy model. The direct forbearer of this paper is the Giordani and Söderlind (2004) study. It begins with the origin, purpose and theoretical grounds of robust control, indicating that it is one way to face model uncertainty, as an alternative to the Bayesian approach. In the middle section, we seek to obtain the course of the model's main variables: interest rates, inflation and output. The model constructor also wants the participating agents to have the same doubts that he has regarding its validity; therefore, robust control is considered as a “fine-tuning” of the rational expectations approach. The impulse-response functions are obtained, with the monetary authority acting as a Stackelberg-type leader, affected by a perturbation on the supply side. The two relevant equilibria are obtained and compared in robust control with dynamic economy (the reference equilibrium and the worst possible case equilibrium) with that obtained when operating with rational expectations. The alternative course for the reference model set forth in the paper by Dennis (2008) is also analysed. We mainly find that the different results depend on the behaviour of the law of motion of the state variables, specifically the shadow prices that influence the private sector's expectations. Lastly, the paper relates the recent monetary policy performance when facing the financial crisis that began in the summer of 2007.     

ADAPTIVE LEARNING AND MONETARY POLICY IN AN OPEN ECONOMY: LESSONS FROM JAPAN

Abstract. Motivated by Japan's economic experiences in recent decades, we incorporate adaptive learning into an open economy dynamic stochastic general equilibrium model to examine the volatility and welfare impact of alternative monetary policies. Comparing four Taylor‐styled policy rules that reflect Japan's monetary policy debates, we first show that imperfect knowledge and the associated learning process induce higher volatility in the economy and that explicit exchange rate stabilization is unwarranted. Moreover, contrary to results under the rational expectation paradigm, we find that while tight inflation controls raise output volatility, they can improve overall welfare under learning by smoothing inflation fluctuations.     

Financial market segmentation,stock market volatility and the role of monetary policy

We study a segmented financial markets model where only the agents who trade stocks encounter financial income risk. In such an economy, the welfare-maximizing monetary policy attains the novel role of redistributing the traders' financial market risk among all agents in the economy. In order to do that, optimal monetary policy reacts to financial market movements; it is expansionary in bad times for the financial markets and contractionary in good ones. In our quantitative exercise, a dividend shock generates different policy responses and consumption paths among the optimal and the 2% inflation targeting policy. The latter implies large distributional welfare losses and risk sharing losses of similar magnitude with those generated by business cycle fluctuations. In addition, the optimal monetary policy does not minimize stock price volatility and implies lower inflation volatility than other commonly used policies.     

Learning stability in economies with heterogeneous agents

An economy exhibits structural heterogeneity when the forecasts of different agents have different effects on the determination of aggregate variables. We study the important case of economies in which agents' behavior depends on forecasts of aggregate variables and show how different forms of heterogeneity in structure, forecasts, and adaptive learning rules affect the conditions for convergence of adaptive learning towards rational expectations equilibrium. Results are applied to an overlapping generations model and a New Keynesian model of monetary policy.     

Welfare and excess volatility of exchange rates

We study the properties of a GEI model with nominal assets, outside money (injected into the economy as in Magill and Quinzii (J Math Econ 21:301–342, 1992)), and multiple currencies. We analyze the existence of monetary equilibria and the structure of the equilibrium set under two different assumptions on the determination of the exchange rates. If currencies are perfect substitutes, equilibrium allocations are indeterminate and, generically, sunspot equilibria exist. Generically, given a nonsunspot equilibrium, there are Pareto improving (and Pareto worsening) sunspot equilibria associated with an increase in the volatility of the future exchange rates. We interpret this property as showing that, in general, there is no clear-cut effect on welfare of the excess volatility of exchange rates, even when due to purely extrinsic phenomena.     

General equilibrium and the new neoclassical synthesis

We present a general equilibrium model of the new neoclassical synthesis that has the same level of generality as the Arrow–Debreu model. This involves a stochastic multi-period economy with a monetary sector and sticky commodity prices. We formulate the notion of a sticky price equilibrium where all agents form rational expectations on prices for commodities and assets, interest rates, and rationing. We present a general result showing that monetary policy imposes no restrictions whatsoever on nominal equilibrium price levels and that the set of sticky price equilibria has a dimension equal to the number of terminal date-events. Stickiness of prices implies that this indeterminacy is real.     

基于MS-VECM模型的我国货币政策非对称研究与启示

通过建立马尔可夫区制转移误差修正模型（MS-VECM）模拟我国货币政策对经济的非对称影响,以此分析我国货币政策的有效性。根据经济波动幅度,将我国经济划分为高波动和低波动两个区制状态,经济增长波动剧烈的区制下向均衡状态调整速度快于经济波动幅度较低区制下的调整,论证了我国货币政策对经济的影响在不同区制下存在非对称性。并用模型对我国经济状况进行了模拟预测,利用这种非线性的模型能够很好地预测货币与产出增长关系,表明现阶段我国经济运行状态是一低波动区制下的正常回落,目前不宜出台强扩张性的货币政策刺激经济增长。     

Fiat money and the value of binding portfolio constraints

We establish necessary and sufficient conditions for the individual optimality of a consumption-portfolio plan in an infinite horizon economy where agents are uniformly impatient and fiat money is the only asset available for intertemporal transfers of wealth. Next, we show that fiat money has a positive equilibrium price if and only if for some agent the zero short sale constraint is binding and has a positive shadow price (now or in the future). As there is always an agent that is long, it follows that marginal rates of intertemporal substitution never coincide across agents. That is, monetary equilibria are never full Pareto efficient. We also give a counter-example illustrating the occurrence of monetary bubbles under incomplete markets in the absence of uniform impatience.     

On the second optimality theorem of welfare economics

To what extent does the second optimality theorem of welfare economics (every Pareto optimal allocation can be repesented as a Walras equilibrium allocation) remain valid when preferences are allowed to be locally satiated? It is always valid for an exchange economy, and is valid for a production economy if there is a consumer who is not locally satiated, but not in general for a production economy where all consumers are locally satiated. A generalized equilibrium is defined, which includes the Walras equilibrium as a special case. Every Pareto optimum can be represented as a generalized equilibrium allocation. Furthermore, every Pareto optimal utility distribution can be realized by a Walras equilibrium allocation.     

Non-stationary,stable Markov processes on a continuous state space

We extend our previous result on simple stable Markov (SSM) processes to the case where the state space is continuous. As anapplication we show the existence of a competitive general equilibrium of a cobweb model where price volatility is generated both by exogenous shocks and by stochastic, so called generating variables (that may be interpreted as sunspots) that govern the correlation of the rational beliefs of individual agents. I would like to thank Danish Social Science Foundation, The Carlsberg Foundation, Stanford Institute for Theoretical Economics (SITE) and Universita Cattolica for financial help. I would also like to thank Trinidad Casasus, Mordecai Kurz, an anonymous referee as well as participants at SITE, ESAM (2004) and ESEM (2004) for helpful discussions and comments. Peter Harremoes provided me with an illuminating counter example and Hiro Nakata provided many comments that helped improve the exposition of the paper. Part of this work is from a paper previously circulated under the title: “Sunspot rational belief structures: anonymity and endogenous uncertainty”.     

Collateral and growth cycles with heterogeneous agents

We investigate the effects of collateral and monetary policy on economic growth within a Ramsey equilibrium model where agents have different discount factors. Introducing liquidity constraints in segmented markets where (poor) impatient agents without collateral have limited access to credit, we study their implications in terms of welfare and business cycles (based on deterministic cycles through bifurcations and self-fulfilling prophecies). We find that an accommodative monetary policy may be growth-enhancing and welfare-improving (through the inequality reduction) while making unpleasant fluctuations more likely. Conversely, a regulation reinforcing the role of collateral and tempering the financial market imperfections may stimulate the economic growth while pursuing the goal of stabilization.     

Floating exchange rates versus a monetary union under rational beliefs: the role of endogenous uncertainty

Using the concept of ex-post optimality, we compare different exchange rate regimes, including floating exchange rates and fixed exchange rates with a Monetary Union in a two country OLG model with stochastic endowments. The emphasis of this comparison is on the welfare consequences of agents having incorrect beliefs. We do not assume that agents can hold any beliefs, but rather that their beliefs are rational that is consistent with the observed empirical behavior of the economy. We study a large set of possible policies, but two of them have our particular interest. The first policy implies devaluations in reaction to a negative shock, while the other implies a fixed exchange rate. These policies have very different consequences. The first will for generic beliefs not result in an ex-post optimal allocation. The other policy is on the other hand always feasible and results in an ex-post optimal allocation. When the two countries form a Monetary Union, the ex-post optimal allocation is also achieved. The meaning of “endogenous uncertainty” as an institutionally induced uncertainty is illustrated. Received: September 1, 2001; revised version: 24 June 2002 RID="*" ID="*" I would like to thank Horace W. Brock, Gianluca Cassese, Paula Orlando, Ho-Mou Wu as well as seminar participants at Copenhagen Business School, ESEM98, Keio University, Kyoto University, Osaka University, SITE (Stanford) and University of Copenhagen for many useful comments on the paper. I am also grateful to Mark J. Garmaise, Takako Fujiwara-Greve, and an anonymous referee for many helpful suggestions for improving the paper. Without the many discussions about Rational Beliefs and related issues I have had with Mordecai Kurz over the years, the research presented here would not have been possible. Financial support from The Carlsberg Foundation, Danish Social Research Council, University of Copenhagen and SITE is gratefully acknowledged.     

The impact of inflation targeting: Testing the good luck hypothesis

Starting in the mid‐1980s, the level and volatility of inflation decreased across industrial countries. The inflation stabilization can be explained by a shift in monetary policy or by a lucky period of low volatility in business cycle shocks. To test the “good luck hypothesis,” we examine the inflation experience of Canada, one of the earliest and most successful adopters of an inflation targeting monetary policy. We Kalman‐filter the historical structural shocks consistent with an estimated dynamic stochastic general equilibrium (DSGE) model of the Canadian economy. The estimated shocks are used to build counterfactual histories. The good luck hypothesis can explain only a minor portion of the change in the path and volatility of inflation after the shift in policy. Most of inflation and output stabilization is accounted by the impact on expectations. Unconditionally, the inflation targeting policy does not improve on the previous policy in terms of inflation volatility, but supports a more favourable trade‐off, reducing substantially output volatility.     

Money and Price Dispersion

We relax restrictions on the storage technology in a prototypical monetary search model to study price dispersion. In this case, buyers and sellers enter matches with potentially different willingness to trade. Across the distribution of possible bilateral matches, prices generally will differ even though agents have identical preferences and technologies. We provide existence conditions for a particularly simple equilibrium pattern of exchange. We prove that in the limiting case where search frictions are eliminated, equilibrium prices are uniform. We also show that a higher initial money stock can raise the average price level and increase price dispersion.