A representative consumer uses Bayes' law to learn about parameters of several models and to construct probabilities with which to perform ongoing model averaging. The arrival of signals induces the consumer to alter his posterior distribution over models and parameters. The consumer's...

A representative investor does not know which member of a set of well-defined parametric "structured models'' is best. The investor also suspects that all of the structured models are misspecified. These uncertainties about probability distributions of risks give rise to components of...

A decision maker suspects that parameters of a set of structured parametric probability models vary over time in unknown ways that he does not describe probabilistically. He expresses a fear that all of these parametric models are misspeci ed by also wanting to consider alternative unstructured...