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Sto caricando le informazioni... Rational Herds: Economic Models of Social Learningdi Christophe P. Chamley
Nessuno Sto caricando le informazioni...
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Penguins jumping off a cliff, economic forecasters and financial advisors speculating against a currency, and farmers using traditional methods in India are all practising social learning. Such learning from the behavior of others may and does lead to herds, crashes, and booms. These issues have become, over the last ten years, an exciting field of research in theoretical and applied economics, finance, and in other social sciences. This book provides both an informal introduction and in-depth insights into the subject. Each chapter is devoted to a separate issue: individuals learn from the observations of actions, the outcomes of these actions, and from what others say. They may delay or make an immediate decision; they may compete against others or gain from cooperation; they make decisions about investment, crop choices, and financial investments. The book highlights the similarities and the differences between the various cases. Non sono state trovate descrizioni di biblioteche |
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 Google Books — Sto caricando le informazioni...GeneriSistema Decimale Melvil (DDC)303.3Social sciences Social Sciences; Sociology and anthropology Social Processes Coordination and control ; PowerClassificazione LCVotoMedia: (2.83)
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For example, in a proof by contradiction on page 49, Chamley assumes that constant-gain learning implies convergence of agents' beliefs to zero variability over time. Really, Chamley? Have you even read any of the economic learning literature outside your own fumbling attempts?
And in his very first example of Bayesian inference, he uses this bizarre assumption: In making a report to the police about a car accident, a witness doesn't report what he observed; rather, he reports his Bayesian inference about what he observed, as if it were his observation. Chamley’s point is that this causes information to be mis-used by the society, under some circumstances, but the entire problem is an artifact of the weird assumption about the witness's behavior!
Furthermore, the assumption that the witness is a rational Bayesian implies the witness will follow the same reasoning that Chamley follows. So the witness knows that his method of reporting is socially suboptimal… but he does it anyway! For a witness that is purely disinterested (as Chamley assumes), that makes no sense.
It is especially strange that Chamley offers this invalid example, because there are plenty of valid examples in which rational agents use information suboptimally in equilibrium.
Sad, this could have been a useful book. As it is, though: Stay away. (