As we have seen in Part I, the rational inattention framework of Christopher Sims aims to capture the best a rational agent can do when his capacity for processing information is limited. This rationally inattentive agent, however, has no reason to question his statistical model. In this post we will examine the robustness framework of Thomas Sargent, which deals with the issue of model uncertainty, but does not assume any capacity limitations.
Economic activity involves making decisions. In order to make decisions, agents need information. Thus, the problem of acquisition, transmission, and uses of information has been occupying the economists’ attention for some time now (there is even a whole subfield of “information economics”). It is not surprising, therefore, that information theory, the brainchild of Claude Shannon, would eventually make its way into economics. In this post and the one to follow, I will briefly describe two specific strands of information-theoretic work in economics: the rational inattention framework of Christopher Sims and the robustness ideas of Thomas Sargent. (As an interesting aside: Sims and Sargent have shared the 2011 Nobel Memorial Prize in Economics, although not directly for their information-theoretic work, but rather for their work related to causality.)