Social Networks and Unraveling in Labor Markets

This paper studies the phenomenon of early hiring in entry-level labor markets (e.g. the market for gastroenterology fellowships and the market for judicial clerks) in the presence of social networks. We o¤er a two-stage model in which workers in training institutions reveal information on their own ability over time. In the early stage, workers receive a noisy signal about their own ability. The early information is ?soft?and non-veri?able, and workers can convey the information credibly only to ? rms that are connected to them (potentially via their mentors). At the second stage, ? hard? veri?able (and accurate) information is revealed to the workers and can be credibly transmitted to all ?rms. We characterize the e¤ects of changes to the network structure on the unraveling of the market towards early hiring. Moreover, we show that an e¢ cient design of the matching procedure can prevent unraveling.Networks; market design; unraveling; entry-level labor markets; early hiring

Community Structure and Market Outcomes: A Repeated Games in Networks Approach

Consider a large market with asymmetric information, in which sellers choose whether to cooperate or deviate and ?cheat?their buyers, and buyers decide whether to re-purchase from di¤erent sellers. We model active trade relationships as links in a buyer-seller network and suggest a framework for studying repeated games in such networks. In our framework, buyers and sellers have rich yet incomplete knowledge of the network structure; allowing us to derive meaningful conditions that determine whether a network is consistent with trade and cooperation between every buyer and seller that are connected. We show that three network features reduce the minimal discount factor necessary for sustaining cooperation: moderate competition, sparseness, and segregation. We ? nd that the incentive constraints rule out networks that maximize the volume of trade and that the constrained trade maximizing networks are in between ?old world? segregated and sparse networks, and a ?global market?Buyer-Seller networks; repeated games; moral hazard;asymmetric information; trust; cooperation; institutions

The Value of Network Information

The business model of companies such as Facebook, MySpace, and Twitter, relies on monetizing the information on the interactions and influences of their users. How valuable is such information, and is its use beneficial or detrimental for consumer welfare? We study these questions in a model where a monopoly sells a network good and may price discriminate using network information: information on consumers influences and/or on consumers susceptibilities to influence. Our framework incorporates a rich set of market products, including goods characterized by global and local network effects. We derive results on the value of network information and determine under which conditions, relative to uniform price, consumer surplus increases. We demonstrate the applicability of our framework using survey data on various types of relationships

Bilateral and Community Enforcement in a Networked Market with Simple Strategies

We present a model of repeated games in large buyer-seller networks in the presence of reputation networks via which buyers share information about past transactions. The model allows us to characterize cooperation networks - networks in which each seller cooperates (by providing high quality goods) with every buyer that is connected to her. To this end, we provide conditions under which: [1] the incentives of a seller s to cooperate depend only on her beliefs with respect to her local neighborhood - a subnetwork that includes seller s and is of a size that is independent of the size of the entire network; and [2] the incentives of a seller s to cooperate can be calculated as if the network was a random tree with seller s at its root. Our characterization sheds light on the welfare costs of relying only on repeated interactions for sustaining cooperation, and on how to mitigate such costs.Networks, moral hazard, graph theory, repeated games

Pricing Network Effects

The increase in the information that firms can collect or purchase about network effects across consumers motivates two important questions: how does a firm's pricing strategy react to detailed information on network effects? Are the availability and use of such information beneficial or detrimental to consumer surplus? We develop a model in which a monopoly sells a network good and price discriminates based on information about consumers' influence and consumers' susceptibility to influence. The monopoly optimally offers consumers price discounts for their influence and charges price premia for their susceptibility; the price premia and the price discounts are simple functions of the pattern of network effects.We determine under which conditions, relative to uniform price, consumer surplus increases, and we characterize the value of information on network effects for the monopoly

We study the va...

Note: The Discussion Papers in this series are prepared by members of the Department of Economics, University of Essex, for private circulation to interested readers. They often represent preliminary reports on work in progress and should therefore be neither quoted nor referred to in published work without the written consent of the author. The Value of Network Informatio

A Consistent Weighted Ranking Scheme with an Application to NCAA College Football Rankings

The NCAA college football ratings, in which the "so-called" national champion is determined, has been plagued by controversies the last few years. The difficulty arises because there is a need to make a complete ranking of teams even though each team has a different schedule of games with a different set of opponents. A similar problem arises whenever one wants to establish a ranking of patents or academic journals, etc. in which the raw data are (incomplete) bilateral citations or interactions among objects. This paper develops and estimates a simple consistent weighted ranking (CWR) scheme which, in the sports world, depends on four parameters (winning vs. losing and the relative importance of home vs. away games). In most ranking problems, there are not explicit criteria to evaluate the success of proposed rankings. NCAA college football has a special structure that enables the evaluation of each ranking scheme. Each season is essentially divided into two parts: the regular season and the post season bowl games. If a ranking scheme is accurate it should correctly predict a relatively large number of the bowl game outcomes. We use this structure to estimate the four parameters of our ranking function using "historical" data from the 1999-2003 seasons.NCAA football; ranking; sport tournament