efficient and durable decision rules with incomplete information we compare six concepts of efficiency for economies with incomplete information depending on the stage at which individuals welfare is evaluated and on whether incentive constraints are recognized an example is shown in which an incentive efficient decision rule may be unanimously rejected by the individuals in the economy we define durable decision rules which can resist such unanimous rejection and show that efficient durable decision rules exist

efficient resource allocation on the basis of priorities many institutions allocate resources by non market mechanisms based on priorities in this paper we introduce a model of resource allocation on the basis of priorities and address the following questions is it possible to allocate resources on the basis of any priority structure if yes when can we do this pareto efficiently without creating incentives for manipulation and consistently across different groups of agents and resource levels we adopt a basic indivisible objects model with a finite number of object types and a finite quota of goods of each type some interesting examples are the determination of access to education allocation of graduate houses offices or tasks agents are assumed to have strict preferences over object types and remaining unassigned an assignment is an allocation of the objects to the agents such that every agent receives at most one object a rule associates an assignment to each preference profile we formalize a priority structure to be a collection of strict priority rankings of individuals indexed by the object types where i a j would be read as i has higher priority for object a than j we assume that the priority structure is exogenously fixed and allow the preferences of the agents to vary a rule is said to violate a priority of i for a if there is a preference profile under which i envies j who is assigned a and publication information econometrica 70 6 november 2002 2489 2497 the copyright to this article is held by the econometric society http www econometricsociety org it may be downloaded printed and reproduced only for personal or classroom use absolutely no downloading or copying may be done for or on behalf of any for profit commercial firm or other commercial purpose without the explicit permission of the econometric society for this purpose contact julie p gordon executive director of the society at jpg northwestern edu i would like to thank faruk gul wolfgang pesendorfer the co editor the four anonymous referees and the participants of the micro theory lunch seminar in princeton university for their comments and suggestions

building criminal capital behind bars peer effects in juvenile corrections this paper analyzes the influence that juvenile offenders serving time in the same correctional facility have on each other s subsequent criminal behavior the analysis is based on data on over 8 000 individuals serving time in 169 juvenile correctional facilities during a two year period in florida these data provide a complete record of past crimes facility assignments and arrests and adjudications in the year following release for each individual to control for the non random assignment to facilities we include facility fixed effects thereby estimating peer effects using only within facility variation over time we find strong evidence of peer effects for various categories of theft burglary and felony drug and weapon crimes the influence of peers primarily affects individuals who already have some experience in a particular crime category we also find evidence that peer effects are stronger in smaller facilities and that the predominant types of peer effects differ in residential versus non residential facilities effects in the latter are consistent with network formation among youth serving time close to home

on the generic inefficiency of differentiable market games it is shown that a differentiable market game remains generically inefficient when its strategic outcome function is perturbed smoothly the proof is based on thom s transversality theorem and removes any restriction regarding the dimension of the strategy spaces a converse result is that almost all efficient market games that are competitive are characterized by bertrand like non differentiabilities finally a synthesis between the cournot and bertrand type approaches to walrasian equilibrium as recently developed in the literature is suggested

on stable and strategy proof rules in matching markets with contracts abstract this paper studies stable and one sided strategy proof rules in many to one matching markets with contracts not assuming any kind of substitutes condition or the law of aggregate demand we obtain the following results first the number of stable and strategy proof rules is at most one second the doctor optimal stable rule whenever it exists is the unique candidate for a stable and strategy proof rule third a stable and strategy proof rule whenever it exists is second best optimal for doctor welfare in that no individually rational and strategy proof rule can dominate it this last result is further generalized to non wasteful and strategy proof rules due to the weak assumptions our analysis covers a broad range of markets including cases where a unique stable and strategy proof rule is not equal to the one induced by the cumulative offer process or the deferred acceptance algorithm

social networks and technology adoption in northern mozambique despite their potentially strong impact on poverty agricultural innovations are often adopted slowly using a unique household dataset on sunflower adoption in mozambique we analyse whether and how individual adoption decisions depend upon the choices of others in the same social networks since farmers anticipate that they will share information with others we expect farmers to be more likely to adopt when they know many other adopters dynamic considerations however suggest that farmers who know many adopters might strategically delay adoption to free ride on the information gathered by others we present empirical evidence that shows that the relationship between the probability of adoption and the number of known adopters is shaped as an inverse u in line with information sharing the network effect is stronger for farmers who report discussing agriculture with others the data contains information which is needed to ameliorate the identification issues that commonly arise in this context in particular social networks are precisely identified and in addition we can control for village heterogeneity and endogenous group formation

the value of connections evidence from the italian american mafia using declassified federal bureau of narcotics records on 800 us mafia members active in the 1950s and 1960s and on their connections within the organized crime network i estimate network effects on gangsters economic status lacking information on criminal proceeds i measure economic status exploiting detailed information about their place of residence housing values are reconstructed using current deflated transactions recorded on zillow com i deal with the potential reverse causality between the economic status and the gangster s position in the network exploiting exogenous exposure to potential pre immigration connections in the absence of pre immigration data i use the informational content of surnames called isonomy to measure the place of origin the instrument is valid as long as conditional on the characteristics of the gangsters including the region of birth and a rich set of controls about the gangsters legal and illegal activities such exposure influences the gangsters importance inside the network called centrality but not the preference for specific housing needs a standard deviation increase in closeness centrality increases economic status by between one forth ols and one standard deviation 2sls

price quantity strategic market games this paper is yet another in a rapidly growing series e g 2 11 on strategic approaches to economic equilibrium our aim here is to make precise the remark implicitly due to bertrand 1 or 10 ch 4 5 that if the agents in an economy use price setting strategies then the strategic nash equilibria will in fact be walrasian and this without any assumption of a large number of small agents however in our models not only prices but also quantities are set by the agents thus it might actually be more appropriate to call them bertrand cournot types of models we begin with a standard walras exchange economy with a finite number of traders and commodities this is recast as a game in strategic form in essentially two different ways there is a trading post for each commodity to which traders send contingent statements about how much they wish to buy and sell and at what prices in model 1 the trading point is determined by the intersection of the aggregate supply and demand curves in model 2 trade takes place so as to meet as many contingent statements as possible each buyer whose orders are filled pays the price he quoted using a fiat money which can be borrowed costlessly and limitlessly but after trade is over there is a settlement of accounts and a penalty is levied on those who are bankrupt no attempt is made to model the penalty in any detail it is simply described in the form of a disutility but this in turn may be imagined to stem from confiscation of assets see remark 5 or the necessity of procuring highly priced loans etc call a noncooperative equilibrium active if it turns out that no trader is isolated i e trapped as the sole buyer or seller at some trading post then our results may be described as follows in model 1 the active2 n e of the game coincide with the c e of the market furthermore there is a subset of tight active n e which also coincide with the c e and each n e in this subset is strong

kinship and financial networks formal financial access and risk reduction kinship networks are beneficial for smoothing consumption and investment but the channels are not well understood we study the financing devices used for consumption and investment by thai households households that are connected to banks achieve significantly better consumption smoothing than unconnected households indirect connections via inter household borrowing are as effective as direct borrowing investment appears to be facilitated by kinship households with kin in the village display reduced sensitivity of investment to income while connections to banks do not significantly reduce sensitivity kin may act as implicit collateral permitting borrowing that would violate repayment constraints in its absence

shadow economies size causes and consequences using various methods the size of the shadow economy in 76 developing transition and oecd countries is estimated average size varies from 12 percent of gdp for oecd countries to 23 percent for transition countries and 39 percent for developing countries increasing taxation and social security contributions combined with rising state regulations are driving forces for the increase of the shadow economy especially in oecd countries according to some findings corruption has a positive impact on the size of the shadow economy and a growing shadow economy has a negative effect on official gdp growth

an econometric model of housing price permanent income tenure choice and housing demand abstract this paper addresses the determination of housing price permanent income tenure choice and housing demand full housing demand elasticities incorporate the interactive effects among the four stages of the model price and income have major effects in the tenure choice equation sociodemographic variables such as age have complex effects that may be lost in simpler forms of estimation

strategyproof assignment by hierarchical exchange we give a characterization of the set of group strategyproof pareto optimal and reallocation proof allocation rules for the assignment problem where individuals are assigned at most one indivisible object without any medium of exchange although there are no property rights in the model the rules satisfying the above criteria imitate a trading procedure with individual endowments in which individuals exchange objects from their hierarchically determined endowment sets in an iterative manner in particular these assignment rules generalize gale s top trading cycle procedure the classical rule for the model in which each individual owns an indivisible good

linear inequality methods to enforce partnerships under uncertainty an overview we review different generic conditions on stochastic outcome functions to enforce either efficient or nearly efficient partnerships their logical relationship is explored two kinds of conditions are considered however the property for an action profile to be compatible plays a crucial role in both kinds also two kinds of enforcement mechanisms are considered enforcement through utility transfers and enforcement through repetition

why do popular mechanisms lack efficiency in random environments we consider the problem of randomly assigning n indivisible objects to n agents recent research introduced a promising mechanism the probabilistic serial that has superior e ciency properties than the most common real life mechanism random priority on the other hand mechanisms based on gale s celebrated top trading cycles method have long dominated the indivisible goods literature with the exception of the present context thanks to their outstanding e ciency features we present an equivalence

network effects and welfare cultures we empirically examine the role of social networks in welfare participation using data on language spoken at home to better infer networks within an area our empirical strategy asks whether being surrounded by others who speak the same language increases welfare use more for those from high welfare using language groups this methodology allows us to include local area and language group fixed effects and to control for the direct effect of being surrounded by one s language group these controls eliminate many of the problems in previous studies the results strongly confirm the importance of networks in welfare participation

on the operation of multiple matching markets abstract we provide a new perspective on how to operate matching markets when there are many types of markets our finding is that the market wise adaptation of strategy proof and non wasteful rules yields a strategy proof rule with the following efficiency property no strategy proof rule pareto dominates the rule such rules are abundant as they include the market wise use of the well known priority based rules of the top trading cycles and the deferred acceptance this result gives theoretical support to the independent operation of markets observed in real life markets as well as our practice in market design that separately treats each market for its design

the social organization of conspiracy illegal networks in the heavy electrical equipment industry we analyze the social organization of three well known price fixing conspiracies in the heavy electrical equipment industry although aspects of collusion have been studied by industrial organization economists and organizational criminologists the organization of conspiracies has remained virtually unexplored using archival data we reconstruct the actual communication networks involved in conspiracies in switchgear transformers and turbines we find that the structure of illegal networks is driven primarily by the need to maximize concealment rather than the need to maximize efficiency however network structure is also contingent on information processing requirements imposed by product and market characteristics our individual level model predicts verdict guilt or innocence sentence and fine as functions of personal centrality in the illegal network network structure management level and company size people of the same trade seldom meet together but the conversation ends in a conspiracy against the public or in some diversion to raise prices

strategy proof stochastic assignment abstract i study strategy proof assignment mechanisms where the agents reveal their preference rankings over the available objects a stochastic mechanism returns lotteries over deterministic assignments and mechanisms are compared according to first order stochastic dominance i show that non wasteful strategy proof mechanisms are not dominated by strategy proof mechanisms however non wastefulness is highly restrictive when the mechanism involves randomization in fact the random priority mechanism i e the random serial dictatorship and a recently adopted school choice mechanism deferred acceptance with random tie breaking are wasteful i find that both these mechanisms are dominated by strategy proof mechanisms in general strategy proof improvement cannot be due to merely reshuffling objects and therefore must involve assigning more objects

incentives in the probabilistic serial mechanism abstract the probabilistic serial mechanism bogomolnaia and moulin 2001 9 is ordinally efficient but not strategy proof we study incentives in the probabilistic serial mechanism for large assignment problems we establish that for a fixed set of object types and an agent with a given expected utility function if there are sufficiently many copies of each object type then reporting ordinal preferences truthfully is a weakly dominant strategy for the agent regardless of the number of other agents and their preferences the non manipulability and the ordinal efficiency of the probabilistic serial mechanism support its implementation instead of random serial dictatorship in large assignment problems

general equilibrium concepts under imperfect competition a cournotian approach in a pure exchange economy we propose a general equilibrium concept under imperfect competition the cournotian monopolistic competition equilibrium and compare it to the cournot walras and the monopolistic competition concepts the advantage of the proposed concept is to require less computational ability from the agents the comparison is made first through a simple example then through a mon abstract concept the p equilibrium based on a general notion of price coordination c 1997 academic press

poor institutions rich mines resource curse in the origins of the sicilian mafia with weak law enforcement institutions a positive shock to the value of natural resources may increase demand for private protection and opportunities for rent appropriation through extortion favouring the emergence of mafia type organisations we test this hypothesis by investigating the emergence of the mafia in twentieth century sicily where a severe lack of state property rights enforcement coincided with a steep rise in international demand for sulphur sicily s most valuable export commodity using historical data on the early incidence of mafia activity and on the distribution of sulphur reserves we document that the mafia was more present in municipalities with greater sulphur availability

random matching under dichotomous preferences we consider bilateral matching problems where each person views those on the other side of the market as either acceptable or unacceptable an acceptable mate is preferred to remaining single and the latter to an unacceptable mate all acceptable mates are welfare wise identical using randomization many efficient and fair matching methods define strategyproof revelation mechanisms randomly selecting a priority ordering of the participants is a simple example equalizing as much as possible the probability of getting an acceptable mate across all participants stands out for its normative and incentives properties the profile of probabilities is lorenz dominant and the revelation mechanism is group strategyproof for each side of the market our results apply to the random assignment problem as well

how to organize crime in criminal organizations diffusing information widely throughout the organization might lead to greater internal efficiency in particular since these organizations are self sustaining through enhancing trust however this may come at the cost of leaving the organization more vulnerable to external threats such as law enforcement we consider the implications of this trade off and characterize the optimal information structure rationalizing both hierarchical structures and organization in cells then we focus on the role of the external authority characterize optimal detection strategies and discuss the implications of different forms of enforcement on the internal structure of the organization and policy finally we discuss a number of applications and extensions in this paper we study the interplay between trust within an illegal organization and its vulnerability to the authorities illegal organizations function more effectively when the people who constitute them trust each other we argue that information sharing is an important factor in building internal trust and cohesion but that can leave the organization vulnerable understanding how this trade off affects an organization s information structure and productivity can allow us to assess detection policies designed to destabilize such organizations since 9 11 the u s congress has passed a 400 billion annual budget for the war on terror new domestic institutions have been created or enhanced among many others the counterterrorism section at the u s department of justice s criminal division international intelligence cooperation has been strengthened and new protocols and controversial legal tools such as the patriot act have been developed however these new agencies and institutions face the same basic questions that have challenged the prosecutors fighting organized crime in italy south america and eastern asia as well as authorities fighting terrorism all over the world now and in the past how can we learn about the internal structure of criminal organizations how should we go about investigating a criminal organization in order to break its internal cohesion how does a criminal organization react to investigation policies we highlight the fact that simply understanding the information links within an organization gives us insight into addressing these questions the anecdotal evidence suggests that there is a wide heterogeneity across the information structures of different criminal organizations the most credited theory about the mafia developed in the early 1990 s has identified the so called cupola as the highest level of the organization supposedly consisting of agents who hold large amounts of information about the organization itself and carry out the enforcement needed for the organization to function 2 these crucial agents are shielded from the authorities since they are typically not directly involved in criminal activities this theory suggests a centralized information and enforcement structure 1 previous drafts have circulated under the titles power and organizational structure under an external threat

networks in the modern economy mexican migrants in the u s labor market this paper attempts to identify job networks among mexican migrants in the u s labor market the empirical analysis uses data on migration patterns and labor market outcomes based on a sample of individuals belonging to multiple origin communities in mexico over a long period of time each community s network is measured by the proportion of the sampled individuals who are located at the destination the united states in any year we verify that the same individual is more likely to be employed and to hold a higher paying nonagricultural job when his network is exogenously larger by including individual fixed effects in the employment and occupation regressions and by using rainfall in the origin community as an instrument for the size of the network at the destination

liquid markets and competition abstract a market is liquid if no individual s actions have a big effect on the prices of goods traded in that market perfectly competitive markets are therefore perfectly liquid it is well known that market liquidity can be achieved by increasing the number of traders so that individual trades are small compared to total trades we show that even when there are only few traders market liquidity can be achieved through large short sales in which net trades are small relative to gross trades in particular for a natural variant of the market game which permits unlimited short sales we show that there is always a nash equilibrium allocation arbitrarily close to a competitive equilibrium allocation of course not all ne are near competitive only the large short sales ne are nearly liquid and hence close to ce