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An information (or informational) cascade occurs when a person observes the actions of others and then—despite possible contradictions in his/her own private information signals—engages in the same acts. A cascade develops, then, when people “abandon their own information in favor of inferences based on earlier people’s actions”. Information cascades provide an explanation for how such situations can occur, how likely they are to cascade incorrect information or actions, how such behavior may arise and desist rapidly, and how effective attempts to originate a cascade tend to be under different conditions.〔Bikhchandani, S., Hirshleifer, D., and Welch, I. (1992), "A Theory of Fads, Fashion, Custom, and Cultural Change as Informational Cascades," ''Journal of Political Economy'', Volume 100, Issue 5, pp. (pp. 992-1026. ) + button to enlarge.〕 By explaining all of these things, the original Independent Cascade model sought to improve on previous models that were unable to explain cascades of irrational behavior, a cascade's fragility, or the short-lived nature of certain cascades. There are five key conditions in an information cascade model: # There is a decision to be made — for example, whether to adopt a new technology, wear a new style of clothing, eat in a new restaurant, or support a particular political position # A limited action space exists (e.g. an adopt/reject decision).〔(Information Cascades and Rational Herding: An Annotated Bibliography and Resource Reference )〕 # People make the decision sequentially, and each person can observe the choices made by those who acted earlier # Each person has some private information that helps guide their decision. # A person can’t directly observe the private information that other people ''know'', but he or she can make inferences about this private information from what they ''do''. One assumption of Information Cascades which has been challenged is the concept that agents always make rational decisions. More social perspectives of cascades, which suggest that agents may act irrationally (e.g., against what they think is optimal) when social pressures are great, exist as complements to the concept of Information Cascades. While competing models exist, it is more often the problem that the concept of an information cascade is conflated with ideas which do not match the two key conditions of the model, such as social proof, information diffusion, and social influence. Indeed, the term information cascade has even been used to refer to such processes. == Basic model == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Information cascade」の詳細全文を読む スポンサード リンク
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