Michael Woodford je zadnji dve desetletji prva avtoriteta na področju monetarne ekonomike. Veliko truda vlaga v integracijo monetarnega pristopa z novokeynesianskimi modeli (je avtor prvega mikrofundiranega novokeynesianskega modela), predvsem z namenom ciljanja inflacije in iskanja optimalnega odziva ekonomske politike (monetarne in fiskalne) na poslovne cikle (krize). V zadnjih letih, ko je postalo več kot očitno, da je predpostavka racionalnih pričakovanj neumestna za modeliranje obnašanja ekonomskih subjektov, dela Woodford predvsem na eksperimentiranju z različnimi predpostavkami glede pričakovanj v makro modelih. V še svežem članku “Macroeconomic Analysis without the Rational Expectations Hypothesis” (Avgust 2013) podaja izvrsten pregled implikacij različnih vrst pričakovanj za ekonomsko politiko.

A crucial methodological question in macroeconomic analysis is the way in which the expectations of decision makers about future conditions should be modeled. To the extent that behavior is modeled as goal-directed, it will depend (except in the most trivial cases) on expectations; and analyses of the effects of alternative governmental policies need to consider how expectations are endogenously influenced by one policy or another. Finding tractable ways to address this issue has been a key challenge for the extension of optimization-based economic analysis to the kinds of dynamic settings required for most questions of interest in macroeconomics.

The dominant approach for the past several decades, of course, has made use of the hypothesis of model-consistent or “rational expectations” (RE): the assumption that people have probability beliefs that coincide with the probabilities predicted by one’s model. The RE benchmark is a natural one to consider, and its use has allowed a tremendous increase in the sophistication of the analysis of dynamics in the theoretical literature in macroeconomics. Nonetheless, the assumption is a strong one, and one may wonder if it should be relaxed, especially when considering relatively short-run responses to disturbances, or the consequences of newly adopted policies that have not been followed in the past — both of which are precisely the types of situations which macroeconomic analysis frequently seeks to address.

While the assumption that an economy’s dynamics must necessarily correspond to an RE equilibrium may seem unjustifiably strong—and under some circumstances, is a heroic assumption indeed—it does not follow that we should then be equally willing to entertain all possible assumptions about the expectations of economic agents. It makes sense to assume that expectations should not be completely arbitrary, and have no relation to the kind of world in which the agents live; indeed, it is appealing to assume that people’s beliefs should be rational, in the ordinary-language sense, though there is a large step from this to the RE hypothesis.1 We should like, therefore, to replace the RE hypothesis by some weaker restriction, that nonetheless implies a substantial degree of conformity between people’s beliefs and reality — that implies, at the least, that people do not make obvious mistakes.

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Nonetheless, it is probably a mistake to suppose that empirical investigations should identify a single model of expectations that can be judged to have been historically valid, and that can then be treated as the way in which expectations must be formed in the future, for purposes of counterfactual policy analyses. It is more reasonable, in my view, to search for policies that should be robust to a variety of possible specifications of expectations. Of course, it is not possible (and probably would not be desirable, even if feasible) to demand that a policy be robust to all possible views of the world; it is therefore important that macroeconomists continue to seek greater certainty about which models of the economy are more accurate. But one need not settle upon a single model specification before policy analysis is possible.  

Vir: Michael Woodford