We analyze a sequential decision model in which each decision maker looks at the decisions made by previous decision makers in taking her own decision. This is rational for her because these other decision makers may have some information that is important for her. We then show that the decision rules that are chosen by optimizing individuals will be characterized by herd behavior; i.e., people will be doing what others are doing rather than using their information. We then show that the resulting equilibrium is inefficient.

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A Simple Model of Herd Behavior

This paper explores the dynamics of allocation under increasing returns in a context where increasing returns arise naturally: agents choosing between technologies competing for adoption. Modern, complex technologies often display increasing returns to adoption in that the more they are adopted, the more experience is gained with them, and the more they are improved.1 When two or more increasing-return technologies 'compete' then, for a 'market' of potential adopters, insignificant events may by chance give one of them an initial advantage in adoptions. This technology may then improve more than the others, so it may appeal to a wider proportion of potential adopters. It may therefore become further adopted and further improved. Thus a technology that by chance gains an early lead in adoption may eventually 'corner the market' of potential adopters, with the other technologies becoming locked out. Of course, under different 'insignificant events' - unexpected successes in the performance of prototypes, whims of early developers, political circumstances - a different technology might achieve sufficient adoption and improvement to come to dominate. Competitions between technologies may have, multiple potential outcomes. It is well known that allocation problems with increasing returns tend to exhibit multiple equilibria, and so it is not surprising that multiple outcomes should appear here. Static analysis can typically locate these multiple equilibria, but usually it cannot tell us which one will be 'selected'. A dynamic approach might be able to say more. By allowing the possibility of 'random events' occurring during adoption, it might examine how these influence ' selection' of the outcome - how some sets of random 'historical events' might cumulate to drive the process towards one market-share outcome, others to drive it towards another. It might also reveal how the two familiar increasingreturns properties of non-predictability and potential inefficiency come about: how increasing returns act to magnify chance events as adoptions take place, so that

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Competing technologies, increasing returns, and lock-in by historical events*

An informational cascade occurs when it is optimal for an individual, having observed the actions of those ahead of him, to follow the behavior of the preceding individual without regard to his own information. We argue that localized conformity of behavior and the fragility of mass behaviors can be explained by informational cascades.

https://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID1405027_code2024.pdf?abstractid=1286306&mirid=1&type=2

A Theory of Fads, Fashion, Custom, and Cultural Change as Informational Cascades

From the Publisher:
Information Goods -- from movies and music to software code and stock quotes - have supplanted industrial goods as the key drivers of world markets. Confronted by this New Economy, many instinctively react by searching for a corresponding New Economics to guide their business decisions. Executives charged with rolling out cutting-edge software products or on-line versions of their magazines are tempted to abandon the classic lessons of economics, and rely instead on an ever changing roster of trends, buzzwords, and analogies that promise to guide strategy in the information age. Not so fast, say authors Carl Shapiro and Hal R. Varian. In Information Rules they warn managers, "Ignore basic economic principles at your own risk. Technology changes. Economic laws do not." Understanding these laws and their relevance to information goods is critical when fashioning today's successful competitive strategies. Information Rules introduces and explains the economic concepts needed to navigate the evolving network economy. Information Rules will help business leaders and policy makers - from executives in the entertainment, publishing, hardware, and software industries to lawyers, finance professionals, and writers -- make intelligent decisions about their information assets.

/pdf/information-rules-a-strategic-guide-to-the-network-economy-e8wzthah9w.pdf

Information Rules: A Strategic Guide to the Network Economy

/pdf/a-theory-of-fads-fashion-custom-and-cultural-change-as-3s4j8rv8xm.pdf

There are often benefits to consumers and to firms from standardization of a product. We examine whether these standardization benefits can "trap" an industry in an obsolete or inferior standard when there is a better alternative available. With complete information and identical preferences among firms the answer is no; but when information is incomplete this "excess inertia" can occur. We also discuss the extent to which the problem can be overcome by communication.

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Standardization, compatibility, and innovation

A good is often more valuable to any user, the more others use compatible goods. The authors show that this effect may inhibit innovation. If an installed base exists and transition to a new standard must be gradual, early adopters bear a disproportionate share of transient incompatibility costs. This can produce "excess inertia." The installed base, however, is "stranded" if the new standard is adopted: this may create "excess momentum." These dynamic effects have strategic implications. Temporary price cutting can permanently prevent entry; and product preannouncements can be critical in innovation. These strategic actions have ambiguous welfare effects.

Installed base and compatibility : innovation, product preannouncements and predation

theoretical grounds that implicitly colluding oligopolies are likely to behave more competitively in periods of high demand. We then show that, in practice, during those periods, various oligopolistic industries tend to have relatively low prices. The few price wars which have been documented also seem to have taken place during periods of high demand. Finally, we study the possibility that this oligopolistic behavior has macroeconomic consequences. We show that it is possible that the increase in competitiveness that results from a shift in demand towards goods produced by oligopolies may be sufficient to raise the output of all sectors.

A Supergame-Theoretic Model of Price Wars during Booms

We discuss three common mechanisms for achieving coordination, with particular reference to the choice of compatibility standards. The first involves explicit communication and negotiation before irrevocable choices are made: It represents what standardization committees do. The second mechanism, by contrast, involves no explicit communication and depends on unilateral irrevocable choices: It succeeds if one agent chooses first and the other(s) follow(s). This is a simple version of "market leadership." We analyze these two mechanisms in a simple model and show that the committee is more likely to achieve coordination. Moreover, although the committee is slower, it outperforms the market mechanism, even when we allow for the value of speed. Third, we examine a hybrid of the first two mechanisms, in which both communication and unilateral preemptive actions are allowed. We show that, far from worsening its performance, unilateral actions improve the committee system. This hybrid system more closely resembles the committee system, the more important coordination is relative to conflict. (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.)

Coordination Through Committees and Markets

The literature on networks suggests that the value of a network is positively affected by the number of geographically dispersed locations it serves (the "network effect") and the number of its users (the "production scale effect"). We show that as a result a firm's expected time until adoption of technologies with network effects declines in both users and locations. We provide empirical evidence on the adoption of automated teller machines by banks that is consistent with this prediction. Using standard duration models, we find that a bank's date of adoption is decreasing in the number of its branches (a proxy for the number of locations and hence for the network effect) and the value of its deposits (a proxy for number of users and hence for production scale economies). The network effect is the larger of the two effects.

Garth Saloner

Papers

Standardization, compatibility, and innovation

Installed base and compatibility : innovation, product preannouncements and predation

A Supergame-Theoretic Model of Price Wars during Booms

Coordination Through Committees and Markets

Adoption of Technologies with Network Effects: An Empirical Examination of the Adoption of Automated Teller Machines