How helpful is a long memory on financial markets?

Summary. How should portfolio decisions depend on the past? In a simple model with boundedly rational agents we show that there is no universal answer to this question. Both, long and short memory, can be optimal in the appropriate environment. In most cases there is an equilibrium where both dispositions are equally successful. We characterize such equilibria for the case of two assets and two states. For dynamics based on average payoff, equilibria are global attractors whereas discrete choice dynamics in general do not converge to the equilibrium. Received: August 31, 1998; revised version: November 15, 1999     

Heterogeneous learning

There is by now a large literature characterising conditions under which learning schemes converge to rational expectations equilibria (REEs). It has been claimed that these results depend on the assumption of homogeneous agents and homogeneous learning. This paper analyses the stability of REEs under heterogeneous adaptive learning, for the class of self-referential linear stochastic models. Agents may differ in their initial perceptions about the evolution of the economy, the degrees of inertia in revising their expectations, or the learning rules they use. General conditions are provided for local stability of an REE. In general, it is not possible to show that stability under homogeneous learning implies stability under heterogeneous learning. To illustrate how to apply the results, several examples are provided.     

Monetary policy and the choice of a monetary instrument in a stochastic setting

Should the FED try to set some monetary aggregate, or should it try to create certain credit conditions by setting interest rates? This question has been examined extensively within models that are essentially non-stochastic or certainty equivalent; however, the question is not meaningful to the monetary authority unless one postulates a stochastic setting. This paper attempts to analyze the question within a stochastic setting. It illustrates the new dimensions added by incorporating risk adverse economic behavior, “rational” expectations, and randomized policy settings.     

On the welfare equivalence of asset markets and banking in Diamond Dybvig economies

Why do people choose bank deposit contracts over a direct participation in asset markets? In their seminal paper, Diamond and Dybvig’s (1983) answer this question by claiming that bank deposit contracts can implement allocations that are welfare superior to asset markets equilibria. The present paper demonstrates that this claim is false whenever the asset market participants are highly rational.     

What to stabilize in the open economy*

We consider the question how “best” to maintain price‐level stability in an open economy, and evaluate three possible policy choices: (a) a constant money growth rate rule; (b) a fixed exchange rate; and (c) a policy of explicit commitment to a price‐level target. In each case we assume that policy is conducted by injecting reserves into or withdrawing reserves from the “banking system.” In evaluating the three regimes, we adopt the criterion that the “best” policy should leave the least scope for indeterminacy and “excessive” economic volatility. In a steady‐state equilibrium, the choice of regime is largely irrelevant; any steady‐state equilibrium under one regime can be duplicated by an appropriate choice of the “control” variable under any other regime. However, we show that the sets of equilibria under the three regimes are dramatically different. When all countries follow the policy of fixing a constant rate of money growth, there are no equilibria displaying endogenously arising volatility and there is no indeterminacy of equilibrium. Under a regime of fixed exchange rates, indeterminacies and endogenously arising fluctuations are impossible if and only if the country with the low “reserve‐to‐deposit” ratio is charged with maintaining the fixed rate. Finally, when one country targets the time path of its price level, under very weak conditions, there will be indeterminacy of equilibrium and endogenously arising volatility driven by expectations.     

From Judicial Sovereignty to Collective Democracy: The Development of J.R. Commons’ Perspective on Progressive Institutional Change

Abstract:

This article clarifies the significance of “collective democracy” in the works of John R. Commons by comparing it with “judicial sovereignty” in terms of its contribution to “progress.” We can thus answer two issues that Paul D. Bush does not clearly address: (i) what setup for policy formation contributes to progress and (ii) what is the role of economists within a collective democracy? Based on the comparison, the answer to the first question is collective democracy, and regarding the second question, the roles of economists as both economists and “institutional” economists are extrapolated.     

Learning,Large Deviations,And Recurrent Currency Crises*

This article studies a version of Obstfeld's (Journal of International Economics 43 (1997), 61–77) “escape clause” model. The model is calibrated to produce three rational expectations equilibria. Two of these equilibria are E‐stable and one is unstable. Dynamics are introduced by assuming that agents must learn about the government's decision rule. It is assumed they do this using a stochastic approximation algorithm. It turns out that as a certain parameter describing the sensitivity of beliefs to new information gets small, the algorithm converges to a small noise diffusion process. The dynamics of exchange rate changes are then characterized using large deviation techniques from Freidlin and Wentzell (Random Perturbations of Dynamical Systems, Second Edition, Berlin: Springer‐Verlag, 1998). These methods describe the sense in which the limiting distribution of exchange rate changes is approximated by a two‐state Markov‐Switching process, where the two states correspond to the two E‐stable equilibria. The model is calibrated to the exchange rate histories of Argentina, Brazil, and Mexico. Currency crises in these countries resemble the predicted “escape routes” of the model. A key feature of these escape routes is that expectations of a devaluation erupt suddenly, without large contemporaneous shocks. This is consistent with evidence showing that crises are often poorly anticipated by financial markets.     

Rational expectations in microeconomic models: An overview

This paper is an expository introduction to several topics of current research in the general equilibrium theory of rational expectations. More specifically, we discuss the existence of exact and approximate rational expectations equilibria, the implementation of equilibria, the behavior of learning and smoothing processes by which traders construct expectations from repeated observations of the market, and the lagged use of the information revealed by prices in an intertemporal sequence of markets. The purpose of this discussion is to introduce papers on these topics appearing in the Journal of Economic Theory Symposium on Rational Expectations in Microeconomic Models.     

Learning rational expectations in an asset market

Will traders in a risky asset market learn Muthian expectations when they initially lack the necessary information? If some traders learn from their observations, will market dynamics depend only on “fundamentals,” as implied by the Efficient Market Hypothesis? This paper shows that at any finite point in time the answer to these questions is “no”. The context is a constant absolute risk aversion model with two kinds of traders and asymmetric information. The market converges asymptotically to a rational expectations equilibrium where prices depend only on fundamentals and the market is efficient.     

Expectations and optimal monetary policy: A stability problem revisited

A landmark result in the optimal monetary policy design literature is that fundamental-based interest rate rules invariably lead to rational expectations equilibria (REE) that are not stable under adaptive learning. In this paper, we make a novel information assumption that private agents cannot observe aggregate fundamental shocks, and use simple linear forecasting rules for learning. We find that with fundamental-based rules, there exist limited information equilibria that are stable under learning. Moreover, there are multiple equilibria. Learning can be used as a selection tool to identify a unique equilibrium.     

Economic resilience in times of public health shock: The case of the US states

Does adopting social distancing policies amid a health crisis, e.g., COVID-19, hurt economies? Using a machine learning approach at the intermediate stage, we applied a generalized synthetic control method to answer this question. We utilize state policy response differences. Cross-validation, a machine learning approach, is used to produce the “counterfactual” for adopting states—how they “would have behaved” without lockdown orders. We categorize states with social distancing as the treatment group and those without as the control. We employ the state time-period for fixed effects, adjusting for selection bias and endogeneity. We find significant and intuitively explicable impacts on some states, such as West Virginia, but none at the aggregate level, suggesting that social distancing may not affect the entire economy. Our work implies a resilience index utilizing the magnitude and significance of the social distancing measures to rank the states' resilience. These findings help governments and businesses better prepare for shocks.     

Estimating the effects of forward guidance in rational expectations models

Simulations of forward guidance in rational expectations models should be assessed using the “modest policy interventions” framework introduced by Eric Leeper and Tao Zha. That is, the estimated effects of a policy intervention should be considered reliable only if that intervention is unlikely to trigger a revision in private sector beliefs about the way that monetary policy will be conducted. I show how to constrain simulations of forward guidance to ensure that they are regarded as modest policy interventions and illustrate the technique using a medium-scale DSGE model estimated on US data. I find that many experiments that generate the large responses of macroeconomic variables deemed implausible by many economists – the so-called “forward guidance puzzle” – are not modest policy interventions. Those experiments should therefore be treated with caution, since they may prompt agents to believe that there has been a change in the monetary policy regime that is not accounted for within the model. More reliable results can be obtained by constraining the experiment to be a modest policy intervention. In the cases I study, the quantitative effects on macroeconomic variables are more plausible when this constraint is imposed.     

Monetary Policy,Expectations and Commitment*

Commitment in monetary policy leads to equilibria that are superior to those from optimal discretionary policies. A number of interest‐rate reaction functions and instrument rules have been proposed to implement or approximate commitment policy. We assess these rules in terms of whether they lead to a rational expectations equilibrium that is both locally determinate and stable under adaptive learning by private agents. A reaction function that appropriately depends explicitly on private sector expectations performs particularly well on both counts.     

Australian Macroeconomic Policy Experience*

This paper looks at Australian macroeconomic experience from approximately 1912 to 1985. The whole period is divided into five episodes. The idea in preparing this paper was to try to answer three questions namely: how did Australian experience differ from that of other OECD countries, what policy lessons could be learnt, and finally, what light could be shed on the relevance of various macroeconomic theories notably rational expectations. In fact. the questions have by no means been adequately answered though the paper goes furthest in dealing with the first question. I hope it will encourage further discussion and research¹ Anticipating some of the conclusions, the historical review suggests that Australian experiences have been fairly similar to those of other OECD countries. notably European countries. But the timing has sometimes differed the Australian wages explosions have been (more or less) exceptional and recently Australia has been special in having on incomes policy, It also appears that the theory of rational expectations does not get much support from Australian was behaviour, that policy from 1916 to 1981 was not really monetarist, and that fiscal expansions since 1982 have been made possible by the availability of the international capital market.     

Rights: Why do they matter,and to whom?

Following Sen, social choice theorists often formulate rights in terms of relationships between individuals' preferences and social preferences. An alternative “procedural” formulation treats rights as properties of game forms. This paper reviews the debate between the proponents of these two approaches, focusing in particular on Sen's claim that the procedural approach is inflexible in its refusal to make trade-offs between rights violations. It looks at different answers to the question, “Why do rights matter?” It argues that, if a contractarian answer is given, there are good reasons not to make trade-offs.     

The effects of the subprime crisis on the Latin American financial markets: An empirical assessment

The aim of this article is to answer the following question: can the considerable rise in the volatility of the LAC stock markets in the aftermath of the 2007/2008 crisis be explained by the worsening financial environment in the US markets? To this end, we rely on a time-varying transition probability Markov-switching model, in which “crisis” and “non-crisis” periods are identified endogenously. Using daily data from January 2004 to April 2009, our findings do not validate the “financial decoupling” hypothesis since we show that the financial stress in the US markets is transmitted to the LAC's stock market volatility, especially in Mexico.     

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.     

New techniques for estimation of rational expectation models and Volcker deflation

Multivariate autoregressive moving average models are used to form the “reduced forms” of Muth's rational expectation models. One implication of the modern macroeconomic theory is that economic agents' expectations should change in the presence of major policy changes. This paper proposes a simple method for directly comparing the formulation of expectations, and illustrates it by considering the impact of a recent policy change in the US under Paul Volcker of the Federal Reserve Bank. Many new interpretations are based on transfer functions, “gain” calculations, Green's function matrices from solutions of difference equations, and complex conjugate roots to measure cyclical phenomena. Furthermore, the traditional distributed lag models are criticized for arbitrarily assuming that the gain is unity. We provide an equation for minimum mean squared error regulation, and indicate the role played by rational two-step ahead speculations made by economic agents, along with changes therein emanating from the policy change.     

Understanding Markov-switching rational expectations models

We develop a set of necessary and sufficient conditions for equilibria to be determinate in a class of forward-looking Markov-switching rational expectations models and we develop an algorithm to check these conditions in practice. We use three examples, based on the new-Keynesian model of monetary policy, to illustrate our technique. Our work connects applied econometric models of Markov-switching with forward looking rational expectations models and allows an applied researcher to construct the likelihood function for models in this class over a parameter space that includes a determinate region and an indeterminate region.