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Dynamics of Bayesian Updating with Dependent Data and Misspecified Models

Cosma Shalizi

Abstract:

Recent work on the convergence of posterior distributions under Bayesian updating has established conditions under which the posterior will concentrate on the truth, if the latter has a perfect representation within the support of the prior, and under various dynamical assumptions, such as the data being independent and identically distributed or Markovian. Here I establish sufficient conditions for the convergence of the posterior distribution in non-parametric problems even when all of the hypotheses are wrong, and the data-generating process has a complicated dependence structure. The main dynamical assumption is the generalized asymptotic equipartition (or "Shannon-McMillan-Breiman") property of information theory. I derive a kind of large deviations principle for the posterior measure, and discuss the advantages of predicting using a combination of models known to be wrong. An appendix sketches connections between the present results and the "replicator dynamics" of evolutionary theory.



Heidi Sestrich 2009-02-06
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