A crucial challenge for economists is figuring out how people interpret the world and form expectations that will likely influence their economic activity. Inflation, asset prices, exchange rates, investment, and consumption are just some of the economic variables that are largely explained by expectations. Here George Evans and Seppo Honkapohja bring new explanatory power to a variety of expectation formation models by focusing on the learning factor. Whereas the rational expectations paradigm offers the prevailing method to determining expectations, it assumes very theoretical knowledge on the part of economic actors. Evans and Honkapohja contribute to a growing body of research positing that households and firms learn by making forecasts using observed data, updating their forecast rules over time in response to errors. This book is the first systematic development of the new statistical learning approach. Depending on the particular economic structure, the economy may converge to a standard rational-expectations or a "rational bubble" solution, or exhibit persistent learning dynamics. The learning approach also provides tools to assess the importance of new models with expectational indeterminacy, in which expectations are an independent cause of macroeconomic fluctuations. Moreover, learning dynamics provide a theory for the evolution of expectations and selection between alternative equilibria, with implications for business cycles, asset price volatility, and policy. This book provides an authoritative treatment of this emerging field, developing the analytical techniques in detail and using them to synthesize and extend existing research.

Abstract: My dissertation studies models of exchange rate determination that are standard in all respects except that market participants have incomplete knowledge about the economic structure, and employ adaptive learning rules to learn about the economic environment. My work on introducing model uncertainty into standard models is motivated by the well documented fact that when the underlying economic environment is known and is common knowledge to market participants, models under rational expectations cannot account for such basic features of the data as the relative volatility between exchange rate and fundamentals or the predictability of future exchange rate returns by the deviation of the exchange rate from the fundamentals. I partly response to this problem to use an alternative view of expectations, adaptive expectations, which can be a reasonable way to form expectations when the environment is excessively complex. I find that the model under adaptive expectations performs better than rational expectations in explaining why the forward exchange rate as a predictor of the future spot rate generates a large bias, why the maximal depreciation of a currency upon an unexpected monetary shock occurs some periods after the initial shock. I consider a standard monetary model where market participants learn about the economic structure using adaptive learning rules. While market participants are assumed to know the functional form of the stochastic process that drives the fundamentals, they do not know the parameter values which they assess by least squares learning. Market participants must also contend with unannounced regime shifts in the fundamental process. I compare the predictions of the model under adaptive learning to those generated under standard rational expectations and under adaptive expectations. I find that the model under adaptive learning dominates the alternative specifications of expectations in its ability to account for why the fundamentals predict exchange rate returns over long horizons, for generating exchange rate return volatility in excess of fundamentals volatility, and in generating persistent deviations of the exchange rate from the fundamentals. I conclude that the underlying model uncertainty goes far in helping to resolve some longstanding puzzles in the foreign exchange market.

Originally published in 1982. This book deals with exchange-rate determination and the implications of floating rate regimes for the time paths of prices and quantities. It develops a class of stochastic equilibrium models of the open economy operating under flexible exchange rates, assuming that agents are endowed with rational expectations but do not possess full current information as to the state of the world. Chapters look at a model’s response to economic disturbances, the effect on non-traded goods, and cyclical variations of the terms of trade. The final chapter considers a model to investigate purchasing parity issues.

This paper studies dynamic-optimizing model of a semi-small open economy with sticky nominal prices and wages. The model exhibits exchange rate overshooting in response to money supply shocks. The predicted variability of nominal and real exchange rates is roughly consistent with that of G-7 effective exchange rates during the post-Bretton Woods era. The model predicts that a positive domestic money supply shock lowers the domestic nominal interest rate, that it raises output and that it leads to a nominal and real depreciation of the country’s currency. Increases in domestic labor productivity and in the world interest rate too are predicted to induce a nominal and real exchange rate depreciation.

We propose a new explanation for the forward-premium and the delayed-overshooting puzzles. Both puzzles arise from a systematic under-reaction of short-term interest rate forecasts to current innovations. Accordingly, the forward premium is always a biased predictor of future depreciation; the bias can be so severe as to lead to negative coeffcients in the 'Fama' regression; delayed overshooting may or may not occur depending upon the persistence of interest rate innovations and the degree of under-reaction; lastly, for G-7 countries against the U.S., these puzzles can be rationalized for values of the model's parameters that match empirical estimates.

The paper models an adjustable peg exchange rate arrangement as a policy rule with an escape clause under which the timing and magnitudes of realignments are the outcomes of policy optimization decisions. Under the assumptions that market participants are rational, risk averse, and fully informed about the incentives of policymakers, the analysis focuses on the implications for relating realignment expectations to the state variables that enter the policy objective function, for modeling the bias in using forward exchange rates to predict future spot rates, and for characterizing the effectiveness of sterilized intervention.

This paper presents a brief survey of the empirical literature on survey-based exchange rate expectations. The literature in general supports the presence of a non-zero risk premium and rejects the hypothesis of rational expectations. The crucial result is that, while short-run expectations tend to move away from some long-run “normal” values, long-run expectations tend to regress toward them. If this nature of short-run expectations increases the volatility of exchange rate movements, there may be a basis for some official measure to minimize short-run exchange rate movements.