Sticky Prices and Indeterminacy

The aim of this paper is to analyze the link between price rigidity and indeterminacy. This is done within a cash-in-advance economy that is known to exhibit indeterminacy at high degrees of relative risk aversion. My findings show that price stickiness reduces the scope of these sunspot equilibria: to be compatible with indeterminacy, sluggish price adjustment requires degrees of relative risk aversion that prove too high to square with data.     

Learnability and monetary policy: A global perspective

The recent literature on monetary policy design has emphasized the importance of equilibrium determinacy and learnability in the choice of policy rules. This paper contains an analysis of the learnability of the equilibrium in a class of simple, micro-founded models in which the policy authority uses a Taylor-type monetary policy rule. Unlike previous analyses, the model economy is not linearized about a steady state—instead, a global perspective is adopted. Globally, the nonlinear model economy can possess rational expectations equilibria other than the steady state consistent with the inflation target of the monetary authorities. These include a second, low inflation ‘liquidity trap’ steady state, periodic equilibria, and sunspot equilibria. The main results in the paper characterize the conditions under which these alternative equilibria maybe stable under adaptive learning, even when the policy rule obeys the Taylor principle. The stability of multiple equilibria is associated with policy rules which are forecast-based. An important finding is that backward-looking Taylor-type policy rules can guarantee that the unique learnable equilibrium is the steady state associated with the inflation target of the monetary authority.     

Did sunspot forces cause the Great Depression?

We apply a dynamic general equilibrium model to the period of the U.S. Great Depression. In particular, we examine a modification of the real business cycle model in which the possibility of indeterminacy of equilibria arises. In other words, agents’ self-fulfilling expectations can serve as a primary impulse behind fluctuations. We find that the model, driven only by these measured sunspot shocks, can explain well the entire Depression era. That is, the decline from 1929 to 1932, the subsequent slow recovery, and the recession that occurred in 1937-1938.     

Instability of sunspot equilibria in real business cycle models under adaptive learning

We provide conditions under which a general, reduced-form class of real business cycle (RBC) models has rational expectations equilibria that are both indeterminate and stable under adaptive learning. Indeterminacy of equilibrium allows for the possibility that non-fundamental “sunspot” variable realizations can be used to drive the model, and several researchers have offered calibrated structural models where sunspot shocks play such a role. However, we show that the structural restrictions researchers have adopted lead to reduced-form systems that are always unstable under adaptive learning dynamics, thus calling into question the plausibility of these sunspot-driven RBC models.     

Liquidity and asset-market dynamics

This study analyzes economies with an essential role for liquid assets in the exchange process. The model can generate multiple stationary equilibria, across which asset prices, market participation, capitalization, output and welfare are positively related. It can also generate a variety of nonstationary equilibria, even when fundamentals are deterministic and time invariant, including periodic, chaotic and stochastic (sunspot) equilibria with recurrent market crashes. Some equilibria have asset-price trajectories that resemble bubbles growing and bursting. Endogenous private and public liquidity is also introduced. Sometimes it is efficient to provide enough liquid assets to satiate demand; other times it is not.     

Simple Monetary Rules under Fiscal Dominance

This paper asks whether interest rate rules that respond aggressively to inflation, following the Taylor principle, are feasible in countries that suffer from fiscal dominance. We find that if interest rates are allowed to also respond to government debt, they can produce unique equilibria. But such equilibria are associated with extremely volatile inflation. The resulting frequent violations of the zero lower bound make such rules infeasible. Even within the set of feasible rules the welfare optimizing response to inflation is highly negative. The welfare gain from responding to government debt is minimal compared to the gain from eliminating fiscal dominance.     

Adverse selection and the financial accelerator

Many economists believe that credit market distortions create a financial accelerator which destabilizes the economy. This paper shows that when credit market distortions arise from adverse selection they sometimes stabilize the economy rather than destabilize it. The stabilizing forces are closely related to forces that cause overinvestment in static models. When investment projects are equity financed, or when contracts are written optimally, the distortions always stabilize the economy. Thus, stabilizing equilibria are a robust feature of the model. The empirical distinction between accelerator and stabilizer equilibria is subtle. Many empirical tests are unable to distinguish between accelerator and stabilizer equilibria.     

Price dispersion, information and learning

We consider an economy where trade is decentralized and agents have incomplete information with respect to the value of money. Agents’ learning evolves from private experiences and we explore how the formation of prices interacts with learning. We show that multiple equilibria arise, and equilibria with price dispersion entail more learning than equilibria with one price. Price dispersion increases communication about private histories, which in turn increases the overall amount of information in the economy. We also compare ex ante welfare under price dispersion and one price. Our results show that, despite the existence of some meetings where no trade takes place, ex ante welfare under price dispersion may be higher than under one price.     

The Value of Interest Rate Stabilization Policies When Agents Are Learning

We examine the expectational stability (E-stability) of rational expectations equilibrium in the "New Keynesian" model where monetary policy is optimally derived and interest rate stabilization is added to the central bank's traditional objectives of inflation and output stabilization. We consider both the case where the central bank lacks a commitment technology and the case of full commitment. We show that for both cases, optimal policy rules yield rational expectations equilibria that are E-stable for a wide range of empirically plausible parameter values. These findings stand in contrast to Evans and Honkapohja's findings for optimal monetary policy rules in environments where interest rate stabilization is not a central bank objective.     

Banks, private money, and government regulation

We study competition between inside and outside money in economies with trading frictions and financial intermediation. Claims on banks circulate if the redemption rate is low. When the quantity of fiat money is scarce, coexistence of inside and outside money dominates equilibria with a unique medium of exchange. If outside money is ample, banks choose to redeem claims in outside money, which increases welfare. Under binding reserve requirements, tightening monetary policy leads to credit rationing. Our results support recent trends toward lower reserve requirements. However, we also identify situations where restrictions on note issue are beneficial.     

Optimal fiscal policy under multiple equilibria

We study optimal fiscal policy in an economy where (i) search frictions create a coordination problem and generate multiple, Pareto-ranked equilibria and (ii) the government finances the provision of a public good by taxing market activity. The government must choose the tax rate before it knows which equilibrium will obtain, and therefore an important part of the problem is determining how the policy will affect the equilibrium selection process. We show that when the equilibrium selection rule is based on the concept of risk dominance, higher tax rates make coordination on the Pareto-superior outcome less likely. As a result, taking equilibrium-selection effects into account leads to a lower optimal tax rate.     

Currency competition: A partial vindication of Hayek

This paper establishes the existence of equilibria for environments in which outside money is issued competitively. Such equilibria are typically believed not to exist because of a classic overissue problem: if money is valued in equilibrium, an issuer produces money until its value is driven to zero. By backward induction, money cannot have value in the first place. This paper shows that overissuance is not a problem if agents believe that if an issuer produces more than some threshold number of notes, then only those notes issued up to the threshold will be valued; additional notes will be worthless. This result is very general, applying to any monetary economy in which equilibria with and without valued money exist if the money supply is finite. The paper also compares the allocation achieved by a monopolist to that achieved with competitive issuance in both a search and an overlapping-generations environment. The results depend on the environment considered, but two general conclusions arise. First, it is ambiguous whether competitive issuers can achieve a more desirable allocation than a monopolist. Second, with competitive issuance, a licensing agency can always improve on pure laissez-faire and achieve the efficient allocation in the long run.     

Aggregate Stability and Balanced‐Budget Rules

It has been shown that under perfect competition and a Cobb‐Douglas production function, a basic real business cycle model may exhibit indeterminacy and sunspot fluctuations when income tax rates are determined by a balanced‐budget rule (BBR). This paper introduces in an otherwise standard real business cycle model a more general and data‐coherent class of production functions, namely, a constant elasticity of substitution production function. We show that the degree of substitutability between production factors is a key ingredient to understanding the (de)stabilizing properties of a BBR. Then we calibrate the model consistently with the empirical evidence; that is, we set the elasticity of substitution between labor and capital below unity. We show that compared to the Cobb‐Douglas case, the likelihood of indeterminacy under a BBR is greatly reduced in the U.S., the EU, and the UK.     

Steady-state equilibrium with state-dependent pricing

State-dependent pricing models are now an operational framework for quantitative business cycle analysis. The analysis in Ball and Romer [1991. Sticky prices as coordination failure. American Economic Review 81 (3), 539-552], however, suggests that such models may be rife with multiple equilibria, for in their static model, price adjustment is always characterized by complementarity, a necessary condition for multiplicity. We study existence and uniqueness of steady-state equilibrium in a discrete-time state-dependent pricing model. We find only weak complementarity and no evidence of multiplicity. However, nonexistence of symmetric steady-state equilibrium with pure strategies arises in the region of the parameter space between flexible and sticky prices.     

Are non-fundamental equilibria learnable in models of monetary policy?

Recent models of monetary policy can have indeterminacy of equilibria, which is often viewed as a difficulty of these models. We consider the significance of indeterminacy using the learning approach to expectations formation. We employ expectational stability as a selection criterion for different equilibria and derive the expectational stability and instability conditions for forward-looking multivariate models, both without and with lags. The results are applied to several monetary policies.     

Discrete devaluations and multiple equilibria in a first generation model of currency crises

The first generation models of currency crises have often been criticized because they predict that, in the absence of very large triggering shocks, currency attacks should be predictable and lead to small devaluations. This paper shows that these features of first generation models are not robust to the inclusion of private information. In particular, this paper analyzes a generalization of the Krugman-Flood-Garber (KFG) model, which relaxes the assumption that all consumers are perfectly informed about the level of fundamentals. In this environment, the KFG equilibrium of zero devaluation is only one of many possible equilibria. In all the other equilibria, the lack of perfect information delays the attack on the currency past the point at which the shadow exchange rate equals the peg, giving rise to unpredictable and discrete devaluations.     

Equilibrium Indeterminacy and Asset Price Fluctuation in Japan: A Bayesian Investigation

This paper investigates sources of asset price fluctuation in Japan using an estimated financial accelerator model. For explicit treatment of expectational beliefs characterized by sunspots, the model is analyzed over the parameter space where the equilibrium can be indeterminate. We show that indeterminacy arises if the financial accelerator effect is sufficiently large. According to our Bayesian estimation results, Japan's economy was affected by sunspot shocks; however, the contribution of the sunspots to asset price volatility was low. Rather, net worth and cost shocks drove the asset price fluctuation. We find, however, that the sunspots substantially affected capital investment.     

Returns to Scale,Market Power,and the Nature of Price Rigidity in New Keynesian Models with Self‐Fulfilling Expectations

Increasing returns to scale and firms' market power are two potential sources of sunspot expectations in neoclassical models. We show that in New Keynesian models, returns to scale and market power can have fundamentally different implications for broad macroeconomic issues, including self‐fulfilling expectations, depending on the nature of price rigidity. Our findings suggest that the design of stabilization monetary policy can depend on precise knowledge about the economy's real and nominal features. Therefore, a clear understanding of the specific economic environment and its relevance to monetary policymaking for ensuring macroeconomic stability can be an integrated part of monetary policy practice.     

On Complicated Dynamics in Simple Monetary Models

We provide a complete characterization of stationary and nonstationary deterministic equilibria in search models of liquidity with indivisible assets. Two formulations are considered: the usual one with random search and bargaining; and a less common but arguably better one with directed search and posting. Also, we consider general meeting technologies. This is interesting because some results are easy with the particular technologies in previous studies but not in general. As is known, these models have equilibria where endogenous variables change over time as self‐fulfilling prophecies. More surprisingly, we prove there are no equilibria where they cycle in the long run.     

A General Theory (and Some Evidence) of Expectation Traps in Monetary Policy

I show that multiple equilibria are a general property of economies under full monetary policy discretion. Three simple conditions are sufficient to rule out, generically, a unique equilibrium in a static economy. The key departure from Barro and Gordon (1983) is to consider bounded welfare costs of inflation. I also show that in a two Markov equilibrium economy the inflation response to certain perturbations is, generically, qualitatively different in each equilibrium. Finally, I discuss some evidence on inflation dynamics that supports the hypothesis that U.S. monetary policy was caught in an expectation trap during the high inflation episode of the 1970s.