1.

Record Nr.

UNINA9910693954303321

Autore

Acemoglu Daron

Titolo

Bayesian Learning in Social Networks / / Daron Acemoglu, Munther A. Dahleh, Ilan Lobel, Asuman Ozdaglar

Pubbl/distr/stampa

Cambridge, Mass, : National Bureau of Economic Research, 2008

Descrizione fisica

1 online resource : illustrations (black and white);

Collana

NBER working paper series ; no. w14040

Classificazione

C72

D83

Altri autori (Persone)

DahlehMunther A

LobelIlan

OzdaglarAsuman

Soggetti

Noncooperative Games

Search • Learning • Information and Knowledge • Communication • Belief • Unawareness

Lingua di pubblicazione

Inglese

Formato

Materiale a stampa

Livello bibliografico

Monografia

Note generali

May 2008.

Sommario/riassunto

We study the perfect Bayesian equilibrium of a model of learning over a general social network. Each individual receives a signal about the underlying state of the world, observes the past actions of a stochastically-generated neighborhood of individuals, and chooses one of two possible actions. The stochastic process generating the neighborhoods defines the network topology (social network). The special case where each individual observes all past actions has been widely studied in the literature. We characterize pure-strategy equilibria for arbitrary stochastic and deterministic social networks and characterize the conditions under which there will be asymptotic learning -- that is, the conditions under which, as the social network becomes large, individuals converge (in probability) to taking the right action. We show that when private beliefs are unbounded (meaning that the implied likelihood ratios are unbounded), there will be asymptotic learning as long as there is some minimal amount of "expansion in observations". Our main theorem shows that when the probability that each individual observes some other individual from the recent past



converges to one as the social network becomes large, unbounded private beliefs are sufficient to ensure asymptotic learning. This theorem therefore establishes that, with unbounded private beliefs, there will be asymptotic learning an almost all reasonable social networks. We also show that for most network topologies, when private beliefs are bounded, there will not be asymptotic learning. In addition, in contrast to the special case where all past actions are observed, asymptotic learning is possible even with bounded beliefs in certain stochastic network topologies.