learning wage dynamics and firm specific human capital we introduce a dynamic and fully strategic model of wage determination in the presence of firm specific human capital in this model human capital is interpreted as information we show that equilibrium exists and is efficient and that it gives rise to a unique distribution of the social surplus we show further that the equilibrium wage is determined by three factors consideration of these factors allows us to determine when and how the market mechanism enables the worker to capture some of the returns to firm specific human capital we relate our findings to the ongoing empirical debate concerning the return to tenure

nonconvexities in optimal pollution accumulation abstract with a few exceptions the analysis of optimal pollution accumulation or detrimental stock externalities rests on the assumptions that the level of damage is unbounded and that pollution decay increases monotonically with the level of pollution stock we show that these assumptions are restrictive and that their generalization alters the basic economic properties of optimal pollution control we specify a decay function which is concave with low stock levels and convex when pollution is higher we show that although multiple steady states may exist the globally optimal solution may be independent of the initial pollution level it is also possible that there are cutoff levels which determine the optimal long run equilibrium implying that the feedback control law is discontinuous and nonmonotonic bounded damage may have similar implications but in contrast to concave convex decay they may occur even with zero discounting

on the economically optimal exploitation of a renewable resource the case of a convex environment and a convex return function we investigate optimal policies for the exploitation of a renewable resource subject to a concave growth function and a convex return function we prove an important result on the elasticity of the objective function and apply it to give a characterization of the optimal harvesting paths in this class of models in particular we derive conditions such that all optimal programs converge to a fixed point or to a cycle of finite period and hence result in the conservation of the resource we also show which assumptions guarantee that extinction of the stock is optimal that nonconvex preferences or technologies cause problems for economic theory is well known as our model can formally be interpreted as an optimal growth model with nonconcave utility function our results are a further contribution on the dynamics of optimal paths in the general class of economic models with nonconcavities journal of economic literatureclassification numbers c61 e32 q20

oligopoly game price makers meet price takers abstract the paper studies an oligopoly game where firms can choose between price taking and price making strategies on a mixed market price takers are always better off than price makers though the profits of both types decline in the number of price takers we investigate and confront two possibilities of firms decisions about their types forward looking equilibrium reasoning and backward looking individual learning we find that the cournot outcome is the only equilibrium prediction and it is learnable if firms are sufficiently sensitive to profit differences however with a larger number of firms a unilateral deviation from cournot behavior becomes profitable under learning this incentive creates a space for permanent oscillations over different markets with a positive but low number of price takers

a nonsmooth nonconvex model of optimal growth this paper analyzes the nature of economic dynamics in a one sector optimal growth model in which the technology is generally nonconvex nondifferentiable and discontinuous the model also allows for irreversible investment and unbounded growth we develop various tools to overcome the technical difficulties posed by the generality of the model we provide sufficient conditions for optimal paths to be bounded to converge to zero to be bounded away from zero and to grow unboundedly we also show that under certain conditions if the discount factor is close to 1 any optimal path from a given initial capital stock converges to a small neighborhood of the golden rule capital stock at which sustainable consumption is maximized if it is maximized at infinity then as the discount factor approaches 1 any optimal path either grows unboundedly or converges to an arbitrarily large capital stock

the impact of common native language and immigration on imports this paper sheds light on the impact of common native language and immigration both jointly and separately on imports common native language and immigrant networks stimulate bilateral trade relationships by reducing transaction costs through both market creation and the removal of information asymmetries whereas evidence on the importance of weak links for trade provides support for the first channel the need for additional immigrants does not decline if the second mechanism proves to be a driver of trade relationships for estimation of a causal and nonlinear effect of the two common native language and immigration on imports we employ a flexible identification strategy which allows common native language and migration to be endogenous the results suggest that both common native language and immigration raise imports but the impact of common native language is ever increasing with its level whereas that of immigration is of declining importance as its level increases

global equilibrium dynamics with stationary recursive preferences abstract we study the global dynamics of capital accumulation for a general two sector model which is not necessarily convex and where preferences of an infinitely lived agent are stationary but not additively separable we obtain monotonicity and convergence results for capital under normality assumptions on preferences and factor intensity assumptions on technology we then derive results on oscillatory dynamics under alternative factor intensity conditions or under the assumption of inferiority of future utilities finally in an exchange model with two agents we show that utilities will be monotonic or oscillatory depending on the normality or inferiority of the preferences

agent based computational transaction cost economics this article explores the use of agent based computational economics ace for modelling the development of transactions between firms transaction cost economics neglects learning and the development of trust ignores the complexity of multiple agents and assumes rather than investigates the efficiency of outcomes efficiency here refers to minimum cost or maximum profit we model how co operation and trust emerge and shift adaptively as relations evolve in a context of multiple interacting agents this may open up a new area of application for the ace methodology a simulation model is developed in which agents make and break transaction relations on the basis of preferences based on trust and potential profit profit is a function of product differentiation specificity of assets economy of scale and learning by doing in ongoing relations agents adapt their trust in a partner as a function of his loyalty exhibited by his continuation of a relation they also adapt the weight they attach to trust on the basis of realized profit the model enables an assessment of the efficiency of outcomes relative to the optimum as a function of trust and market conditions we conduct a few experiments to illustrate this application of ace

evolving market structure an ace model of price dispersion and loyalty we present an agent based computational economics ace model of the wholesale sh market in marseille two of the stylized facts of that market are high loyalty of buyers to sellers and persistent price dispersion although it is every day the same population of sellers and buyers that meets in the same market hall in our ace model sellers decide on quantities to supply prices to ask and how to treat loyal customers while buyers decide which sellers to visit and which prices to accept learning takes place through reinforcement the model explains both stylized facts price dispersion and high loyalty in a coevolutionary process buyers learn to become loyal as sellers learn to o er higher utility to loyal buyers while these sellers in turn learn to o er higher utility to loyal buyers as they happen to realize higher gross revenues from loyal buyers the model also explains the e ect of heterogeneity of the buyers we analyze how this leads to subtle di erences in the shopping patterns of the di erent types of buyers and how this is

information health risk beliefs and the demand for fats and oils mean and variance measures of health information about cholesterol and saturated fat are included in a demand system for fats and oils a bayesian model of health risk belief and consumer awareness surveys are the basis for computing these measures the empirical demand model shows that health information has resulted in significant increases in consumption for corn cottonseed and soybean oils and decreased consumption for butter and lard the predicted demand effects based on the bayesian information model are more reasonable than predictions from using either a time trend or a simple cumulative cholesterol information index copyright 1995 by mit press

predicting consumer demand responses to carbon labels abstract providing carbon footprint labels for all food products is a daunting and potentially infeasible project knowing how consumers substitute away from high carbon goods and what they choose as substitutes is essential for understanding which goods are likely to result in meaningful reductions in carbon emissions this paper proposes a model to systematically estimate how consumers will respond to information from a carbon footprint label our model uses consumers value of their individual carbon footprint with own and cross price elasticities of demand data on carbon emissions from life cycle analysis to simulate shifts in consumer demand for 42 food products and a non food composite and subsequent changes in carbon emissions from different labeling schemes our simulation results have several findings including 1 carbon labels can reduce emissions but labeling only some items could lead to perverse impacts where consumers substitute away from labeled goods to unlabeled goods with a higher carbon footprint 2 carbon labels can inform consumers such that their previous beliefs about carbon footprints matter and 3 carbon labels on alcohol and meat would achieve the largest decreases in carbon emissions among the 42 food products studied

self fulfilling mechanisms and rational expectations we introduce a class of communication equilibria which we call self fulfilling mechanisms and show that they provide a game theoretic foundation to rational expectations equilibria letebe an exchange economy with differential information we associate a strategic market game e withe we prove that the allocations achieved through a self fulfilling mechanism in e coincide with the rational expectations equilibrium allocations ine in order to understand how self fulfilment can be realized in a dynamic framework we investigate the relationship between self fulfilling mechanisms in e and nash equilibria of thet stage repeated game t e journal of economic literatureclassification numbers d82 c72

increasing returns and crowding out abstract this paper explores how public debt interferes with the accumulation of physical capital when the technology displays a production externality of the arrow romer type we identify conditions under which a small positive amount of debt will prevent the economy from ever approaching the stock of capital that it would achieve if public debt were zero we also show that the interaction of debt and production externalities may produce bounded possibly cycling capital stock sequences in economies where sustained growth rates are possible with zero national debt finally welfare issues concerning the relation between static and dynamic inefficiencies are discussed

market organisation and trading relationships in this paper we give a theoretical model of buyers behaviour on a market for a perishable good where no prices are posted we show that if buyers learn from their own previous experience there is a sharp division between those who learn to be loyal to certain sellers and those who continue to shop around this feature remains in more general models which are simulated and is consistent with empirical data from the marseille fish market

a complete characterization of optimal growth paths in an aggregated model with a non concave production function the convexity of technology has played a crucial role in economic analyses of optimal one sector growth problems for example two of the key results on the traditional model of ramsey 1928 that have relied on the convexity of the technology are that optimal intertemporal growth involves moving monotonically towards a unique steady state as in cass 1965 koopmans 1965 and that the value function is a concave differentiable function of the initial capital stock as in benveniste and scheinkman 1979

the influence of seller learning and time constraints on sequential bargaining in an artificial perishable goods market in this paper we test some hypotheses about the formation of prices through sequential bilateral bargaining on a perishable goods market under the assumption of behavioural learning by buyers and sellers we constructed a multi agent simulation model based on a survey concerning the fruit and vegetables market in marseille france in our model the agents bargain the price of a perishable good the representation of agents rationality is inspired by a literature relative to markets of perishable goods kirman 6 7 and rouchier 18 19 20 as well as on artificial bargaining brenner 2 weisbuch 22 we study the influence of three parameters the sellers initial beliefs concerning the buyers willingness to pay the time spent by buyers on the market and the heterogeneity in the sellers limit value on the evolution of prices and of agents representations of others agents we compare our results with empirical observations and some existing literature on bargaining we find that our assumptions concerning the learning process give consistent results and lead the transactions prices to converge toward the sellers limit value

price formation on the marseille fish market evidence from a network analysis abstract the empirical analysis of fish markets always reveals strong price dispersion for homogeneous or very similar goods the problem is how to explain this price dispersion on a market where there is no evident arbitrage explanations proposed by different authors include differences in organization the characteristics of the good and the influences of social interactions between buyers and sellers in line with the last of these three approaches we consider the fish market of marseille as a seller seller network we start by examining the influence of market interactions through a static and then a dynamic econometric model we then analyze the role of the seller s position in the network we bring to light a surprising paradox in that the sellers who share the most buyers with competitors i e the most central sellers charge the highest prices

stationary optimal policies with discounting in a stochastic activity analysis model we consider optimal capital accumulation in a nonlinear activity analysis model in which production and primary resource supplies are affected by a stationary stochastic process of exogenous shocks the optimality criterion is the sum of discounted expected future social utilities under various neoclassical conditions on technology and preferences i there exists an optimal policy of investment and consumption expressible as a continuous time invariant function of the capital stocks and the history of stochastic shocks and ii there is a stationary stochastic process of capital stocks that is consistent with the optimal policy

crime and social interactions the high variance of crime rates across time and space is one of the oldest puzzles in the social sciences this variance appears too high to be explained by changes in the exogenous costs and benefits of crime we present a model where social interactions create enough covariance across individuals to explain the high cross city variance of crime rates this model provides an index of social interactions which suggests that the amount of social interactions is highest in petty crimes moderate in more serious crimes and almost negligible in murder and rape

co evolution of firms and consumers and the implications for market dominance consider a setting in which rms randomly discover new ideas that a ect their products or services and implement favorable ones at the same time that rms are adapting their o erings consumers are searching among rms for the best match it is shown that implicit in these dual dynamics is an increasing returns mechanism which can result in one rm dominating the market in the long run the conditions under which there is sustained market dominance are characterized

can a stochastic cusp catastrophe model explain stock market crashes this paper is the first attempt to fit a stochastic cusp catastrophe model to stock market data we show that the cusp catastrophe model explains the crash of stock exchanges much better than other models using the data of u s stock markets we demonstrate that the crash of october 19 1987 may be better explained by cusp catastrophe theory which is not true for the crash of september 11 2001 with the help of sentiment measures such as the index put call options ratio and trading volume the former models the chartists the latter the fundamentalists we have found that the 1987 returns are bimodal and the cusp catastrophe model fits these data better than alternative models therefore we may say that the crash has been led by internal forces however the causes for the crash of 2001 are external which is also evident in much weaker presence of bifurcations in the data in this case alternative models explain the crash of stock exchanges better than the cusp catastrophe model

meso comes to markets comment on markets come to bits mirowski s research programme of markomata formally sets out to model the diversity of market forms by making use of the mathematical theory of automata and then to taxonomize and organize these entities by means of a theory of evolution mirowski this issue this suggests a new sort of economics in which it is markets that evolve not people systems that evolve not agents prosthesis that evolve not preferences and rules that evolve not information economies evolve people do not this proposition is both obvious and true making it an excellent foundation for an evolutionary social science so if we are to take mirowski s program seriously as a general framework for economic analysis which we think we certainly should then it is important to recognize that although mirowski s unified rubric of markomata elides agency and is instead based upon john von neumann s theory of automata as a model for the study of social institutions the separate lines of research into markets as computational entities are all still very much but a microeconomics markomata is a theory of the core microeconomic building blocks of an economic system as well as a theory of their evolutionary principles i e a microeconomics but it is not yet a theory of the whole economy yet it is our view that mirowski s markomata program can indeed be the basis for such a general theory when analytically expounded in terms of the new evolutionary economic framework of micro meso macro dopfer et al 2004 and dopfer 2005 in which market automata mirowski and somefun 1998 and potts 2001 are abstracted as a special central instance of generic meso rules dopfer and potts 2004 which is to suggest that the mirowski framework of markomata can be yet further developed

the population problem theory and evidence this study is concerned with the relationships among population growth poverty and environmental degradation with particular focus on the situation in developing countries the author rejects the concept of a general theory of fertility behavior in favor of an interpretation of these relationships which might be applicable to certain situations in the poorest parts of the indian subcontinent and sub saharan africa such situations include unacceptable risks of maternal death for poor illiterate women and a condemnation to extreme poverty in conditions of the deterioration of local resources and of the environment the author concludes that population growth rates are too high in certain specific areas and that an appropriate policy reaction to such conditions would be to try to change the options that men and women face so that their reasoned choice would be to lower their fertility

self fulfilling mechanisms in bayesian games abstract amechanismfor a bayesian gamegis a mapping from the set of states of nature to the set of players actions isself fulfillingif players are truthful at the communication stage and given the information revealed by no player can gain in unilaterally deviating from the action prescribed by the mechanism we investigate the properties of self fulfilling mechanisms and we show in particular that they correspond to inert solutions of the infinitely repeated game generated byg we also discuss applications to market games regulation and r d games journal of economic literatureclassification numbers d82 c72

adaptive learning models of consumer behavior abstract in a model of dynamic duopoly optimal price policies are characterized assuming consumers learn adaptively about the relative quality of the two products a contrast is made between belief based and reinforcement learning under reinforcement learning consumers can become locked into the habit of purchasing inferior goods such lock in permits the existence of multiple history dependent asymmetric steady states in which one firm dominates in contrast belief based learning rules must lead asymptotically to correct beliefs about the relative quality of the two brands and so in this case there is a unique steady state

discrete choice with social interactions this paper provides an analysis of aggregate behavioural outcomes when individual utility exhibits social interaction effects we study generalized logistic models of individual choice which incorporate terms reflecting the desire of individuals to conform to the behaviour of others in an environment of noncooperative decisionmaking laws of large numbers are generated in such environments multiplicity of equilibria in these models which are equivalent to the existence of multiple self consistent means for average choice behaviour will exist when the social interactions exceed a particular threshold local stability of these multiple equilibria is also studied the properties of the noncooperative economy are contrasted with the properties of an economy in which a social planner determines the set of individual choices finally a likelihood function based on the theoretical model is given and conditions for the econometric identifiability of the model are established

a dynamic network model of the unsecured interbank lending market abstract we introduce a dynamic network model of interbank lending and estimate the parameters by indirect inference using network statistics of the dutch interbank market from february 2008 to april 2011 we find that credit risk uncertainty and peer monitoring are significant factors in explaining the sparse core periphery structure of the market and the presence of relationship lending shocks to credit risk uncertainty lead to extended periods of low market activity intensified by reduced peer monitoring moreover changes in the central bank s interest rate corridor have both a direct effect on the market as well as an indirect effect by changing banks monitoring efforts

dynamic instability of a mixed city in the presence of neighborhood externalities it has been often asked whether a city currently accommodating a variety of economic social and racial groups will continue to be a mixed city or will become exclusively occupied by a single group particularly poor blacks with all other groups moving out of the city in the long run in order to answer this question properly it seems essential to develop a long run dynamic model of a city with emphasis on socioeconomic factors like neighborhood externalities within or among various groups of residents as well as spatial factors like the individual choice of residential space and location it might be safely said that in the literature the only theoretical work which employs a long run dynamic approach to this kind of problem is a paper on dynamic models of segregation by thomas schelling 197 1 although his socioeconomic analysis has revealed some of the dynamic properties of a racially mixed area with neighborhood externalities his model itself is quite unsatisfactory from the economic point of view since it lacks individual utility functions and thereby disregards the aspect of the individual choice of space and location within the city 2 as a result he failed to analyze the effect of spatial segregation within the city on the long run nature of the residential composition of the city in this paper i develop a long run dynamic model of an open city which accommodates two groups of households for example blacks and whites rich and poor young and old with their utility functions depending on a consumption good and residential space i also assume two kinds of neighborhood externalities the first is called negative intergroup externalities that is the utility level of a typical household in one group is adversely affected by an increase in the number of households in the other group living in the city the second is called positive intragroup externalities that is the utility level of a typical household in one group is positively affected by an increase in the size of its own group in in the city first i define a mixed city equilibrium as a long run equilibrium which allows the two groups to coexist in the city in the long run and then introduce a dynamic adjustment process of household movement into and out of the city it is proved that the mixed city equilibrium is always unstable in the presence of negative intergroup externalities and or positive intragroup externalities if residential land is perfectly homogeneous and there is no differential transport cost incurred within the city it turns out however that in the case of a monocentric city with positive transport cost the mixed city equilibrium may be stable or unstable depending on the degree of neighborhood externalities because of the stabilizing effect of spatial segregation between the two groups within the city

the economics of non convex ecosystems introduction the word convexity is ubiquitous in economics but absent from economics in this paper we explain why and show what difference it makes to economic analysis if ecosystem non convexities are taken seriously a simple proof is provided of the connection between self similarity and power laws we also provide an introduction to each of the papers in the symposium and draw out the way in which they form a linked set of contributions

aspirations and inequality the premise of this paper is twofold first people s aspirations for their future wellbeing or that of their children aect their incentives to invest second the experiences of others help shape one s aspirations this paper marries a model of aspirations based choice with a simple theory of aspirations formation to study the relationship between aspirations and the distribution of income through its impact on investments aspirations aect economic mobility and the income distribution which in turn shape aspirations thus aspirations income and the distribution of income evolve jointly and in many situations in a self reinforcing way we study the consequences of this model for income distribution as well as for growth rates over dierent quantiles of the distribution we show that extreme equality is unstable moreover when the same aspirations are shared in a society polarization arises the theory we propose captures both the complacency stemming from low aspirations and the frustration resulting from aspirations that are too high as a result for commonly held aspirations growth rates have an inverted u shape along the income distribution

economic assessment of nutritional recommendations abstract the effect of consumers compliance with nutritional recommendations is uncertain because of potentially complex substitutions to lift this uncertainty we adapt a model of consumer behaviour under rationing to the case of linear nutritional constraints dietary adjustments are derived from information on consumer preferences consumption levels and nutritional contents of foods a calibration exercise simulates for different income groups how the french diet would respond to various nutrition recommendations and those behavioural adjustments are translated into health outcomes through the dietron epidemiological model this allows for the ex ante comparison of the efficiency equity and health effects of ten nutritional recommendations although most recommendations impose significant taste costs on consumers they are highly cost effective with the recommendations targeting salt saturated fat and fruits and vegetables f v ranking highest in terms of efficiency most recommendations are also economically progressive with the exception of that targeting f v

ex post regret and the decentralized sharing of information abstract firms reveal private information about the value of investment through their investment decisions as a consequence they may have ex post regret once they see other firms investments we define a notion of rational expectations equilibrium for games which imposes a no regret property in this equilibrium all firms make the same investment decision but despite the absence of ex post regret the investment herd can be inefficient in addition equilibrium might not exist we introduce a notion of probabilistic existence and identify conditions under which if the number of firms is large enough information comes out so that investment herds are first best efficient with high probability and equilibrium exists with high probability journal of economic literatureclassification numbers c7 d8

equilibrium and optimality some imprints of david gale abstract the paper is a review of some of the themes to which david gale made lasting contributions it touches upon a number of the fundamental issues in the walrasian equilibrium theory existence uniqueness and stability the overlapping generations model non optimality and indeterminacy of competitive equilibria the von neumann equilibrium as a turnpike and in the theory of decentralized intertemporal allocation through competitive prices efficiency and golden rules duality and existence of optimal programs

potential dietary outcomes of changing relative prices of healthy and less healthy foods the case of ready to eat breakfast cereals abstract many prevalent and costly health disorders in the u s can be attributed in part to poor diets overconsumption of calories and physical inactivity taxing less healthy foods and subsidizing healthy foods as a strategy to improve diet and health has attracted growing interest among policy makers and researchers we test this strategy by using national household purchase data to estimate a censored price and expenditure endogenous demand system for 12 food groups that are commonly consumed at breakfast low and high nutrition ready to eat breakfast cereals eggs breads hot cereals breakfast bars juice whole and reduced fat milk yogurt meats and coffee the estimated demand elasticities are applied to nationally representative food intake data to simulate under the assumption of perfectly price elastic supply the potential dietary improvement from taxing low nutrition and subsidizing high nutrition ready to eat breakfast cereals we find that the demand for both types of cereals is own price inelastic suggesting that consumers are not likely to make large shifts in consumption of cereals if the price changes thus only limited dietary improvement can be expected from taxes and subsidies furthermore when the healthfulness of breakfast foods is evaluated using a comprehensive list of nutrients and food components a price intervention strategy may result in unintended adverse impacts our simulation results suggest that the hypothetical price intervention actually increases the calorie content of foods consumed at breakfast

marginal contribution reciprocity and equity in segregated groups bounded rationality and self organization in social networks we study the formation of social networks that are based on local interaction and simple rule following agents evaluate the profitability of link formation on the basis of the myerson shapley principle that payoffs come from the marginal contribution they make to coalitions the np hard problem associated with the myerson shapley value is replaced by a boundedly rational spatially myopic process agents consider payoffs from direct links with their neighbours level 1 which can include indirect payoffs from neighbours neighbours level 2 and up to m levels that are far from global agents dynamically break away from the neighbour to whom they make the least marginal contribution computational experiments show that when this self interested process of link formation operates at level 2 neighbourhoods agents self organize into stable and efficient network structures that manifest reciprocity equity and segregation reminiscent of hunter gather groups a large literature alleges that this is incompatible with self interested behaviour and market oriented marginality principle in the allocation of value we conclude that it is not this valuation principle that needs to be altered to obtain segregated social networks as opposed to global components but whether it operates at level 1 or 2 of social neighbourhoods remarkably all m 2 neighbourhood calculations for payoffs leave the efficient network structures identical to the case when m 2

is equality stable economic inequality is of interest not only at some intrinsic level but also for its close connections to diverse variables ranging from economic indicators such as growth rates to sociopolitical outcomes such as collective action and conflict it is only natural then to study the evolution of inequality in an economic system it is fair to say that the dominant view on this topic is that inequality is the outcome of a constant battle between convergence and luck gary becker and nigel tomes 1979 current asset inequalities may echo into the future but their natural tendency is to die out owing to a convex investment technology disparities are only sustained through ongoing stochastic shocks see also david champernowne 1953 glenn loury 1981 a second approach emphasizes that initial conditions determine final outcomes owing principally to a nonconvex investment technology see e g mukul majumdar and tapan mitra 1982 abhijit banerjee and andrew newman 1993 oded galor and joseph zeira 1993 ray and peter streufert 1993 historical disparities may persist and magnify if such differences straddle some bifurcation threshold inequality is not inevitable in this view stable steady states with inequality coexist with others that involve perfect equality in this paper we examine a third view which emphasizes an intrinsic tendency of the market mechanism to create inequality in this approach economic inequality appears as an inevitable outcome even if all agents are identical to begin with and even if there is no uncertainty or technological nonconvexity this view has received attention in ray 1990 debasis bandyopadhyay 1993 lars ljungqvist 1993 scott freeman 1996 kiminori matsuyama 2001 and mookherjee and ray 2001 the basic argument is as follows suppose that an economy is populated by several dynasties each of which allocates resources to current consumption and bequests to descendants assume for the moment that the latter consists entirely of educational expenditures preparing children for their chosen professions of course the returns to such professions are endogenous they depend on the distribution of individuals across different professions now if several professional categories are necessary wages must adjust so as to force separation in choices even if all individuals are ex ante identical to be sure this broken symmetry matsuyama 2002 has no payoff implications for the generation alive today identical individuals must receive identical payoffs starting with the next generation however there must be inequality not just in wages but in payoffs there must be individuals in lowpaying professions that involve low training costs whose parents invested little and there must be others in high paying high trainingcost professions whose parents invested a lot once such inequality sets in it may well magnify richer offspring will find it easier to invest in better paying professions for their children two ingredients are used in this argument first credit markets must be missing or imperfect otherwise the necessary finances may be borrowed and wages net of costs must be equalized over all professions however the assumption that parents cannot borrow against their children s future earnings seems innocuous enough second parents cannot make financial bequests to supplement or substitute for educational expenditures such bequests could conceivably neutralize earnings inequality this motivates the question when might financial bequests compensate for earnings inequality in steady state moreover starting from perfect equality will equality be preserved thereafter or will inequality emerge and persist we discuss an extended example from an ongoing research project mookherjee department of economics boston university 270 bay state road boston ma 02215 ray department of economics new york university 269 mercer street new york ny 10003 and instituto de analisis economico csic barcelona spain we thank kiminori matsuyama who encouraged us to write this paper

hospital quality choice and market structure in a regulated duopoly this paper analyzes the optimal structure of a regulated health care industry in a model in which the regulator cannot enforce what hospitals do unverifiable quality of health or does not know what hospitals know incomplete information about production costs or both we show that if quality is unverifiable the choice between monopoly and duopoly does not change with respect to the verifiable case but if there are fixed costs assumed to be quality dependent and the monopoly is the optimal market structure the quality level of the operative hospital decreases asymmetry of information introduces informational rents that can be reduced by increasing the most efficient hospital s market share a monopoly is chosen more often

equity and efficiency in human capital investment the local connection a general model of community formation and human capital accumulation with social spillovers and decentralized school funding is used to analyse the causes of economic segregation and its consequences for equity and efficiency significant polarization arises from minor differences in endowments preferences or access to capital markets this makes income inequality more persistent across generations but the same need not be true for wealth equilibrium stratification tends to be excessive resulting in low aggregate surplus whether state equalization of school resources can remedy these problems hinges on how purchased social and family inputs interact in education and in mobility decisions

learning to bid in sequential dutch auctions abstract we propose an agent based computational model to investigate sequential dutch auctions with particular emphasis on markets for perishable goods and we take as an example wholesale fish markets buyers in these markets sell the fish they purchase on a retail market the paper provides an original model of boundedly rational behavior for wholesale buyers behavior incorporating learning to improve profits conjectures as to the bids that will be made and fictitious learning we analyze the dynamics of the aggregate price under different market conditions in order to explain the emergence of market price patterns such as the well known declining price paradox and the empirically observed fact that the very last transactions in the day may be at a higher price the proposed behavioral model provides alternative explanations for market price dynamics to those which depend on standard hypotheses such as diminishing marginal profits furthermore agents learn the option value of having the possibility of bidding in later rounds when confronted with random buyers such as occasional participants or new entrants they learn to bid in the optimal way without being conscious of the strategies of the other buyers when faced with other buyers who are also learning their behavior still displays some of the characteristics learned in the simpler case even though the problem is not analytically tractable

market diffusion with two sided learning we analyze the diffusion of a new product of uncertain value in a duopolistic market both sides of the market buyers and sellers learn the true value of the new product from experiments with it buyers have heterogeneous preferences over the products and sellers compete in prices the pricing policies and market shares in the unique markov perfect equilibrium are obtained explicitly the dynamics of the equilibrium market shares display excessive sales of the new product relative to the social optimum in early stages and too low sales later on the diffusion path of a successful product is s shaped

getting consumers to eat more whole grains the role of policy information and food manufacturers the 2005 dietary guidelines were unique because they offered quantitative recommendations for consumption of whole grains this case study examines the hypothesis that the changed recommendations were responsible for the recent increase in retail sales and consumption of whole grain food products we find that release of the dietary guidelines and related media attention did increase availability and sales of whole grain foods a large impact on consumption occurred through reformulation of existing products induced by competition among food suppliers this study reveals the key role product reformulation plays in inter firm competition and in realization of dietary changes recommended by public

the price effect of expanding fish auction markets abstract fish markets can be expanded by two means first by attracting newcomers in a local trading room and secondly by allowing remote bidders to participate in both cases electronic systems have played a key role in french primary fish markets the computerisation of trading rooms started in the mid 1980s while connection through intranet or internet systems first started in the mid 1990s and then has spread more actively in france since 2007 however the socioeconomic impact on prices for example of expanding markets by electronic means is far from being clearly predictable first based on an econometric analysis this article presents evidence of increases in price level and variability after the implementation of local electronic auction systems secondly a comprehensive survey of the 40 fish auction markets in france brings additional information about the effects of electronic remote bidding on fish prices the analysis of these two empirical outcomes uses the cross fertilization of the positivist auction theory in economics with the constructionist approach of actor network theory ant in sociology to enrich the potential hypotheses lying behind the study of the structural impact of electronic systems on market prices

sustained endogenous growth with decreasing returns and heterogeneous capital abstract the possibility of sustained long run growth is typically associated with the presence of some endogenous engine of growth it may allow the economy to grow without bound despite the use of some non reproducible resources such situations can lead to dynamic models combining the features of sustainable growth and decreasing returns one sector models of this kind have recently attracted much attention in macroeconomics applications their approximate linearity for the purposes of long run analysis has been noted this paper is aimed at establishing the general fact dynamic models one or multi sector which are characterized by sustained endogenous growth with non increasing returns display the patterns of optimal growth asymptotically equivalent to those generated by models with linear technology i consider a neoclassical growth model with heterogeneous capital develop its linear counterpart and prove their asymptotic equivalence in terms of long run optimal growth rates and cross sectoral profiles of consumption real interest rates and relative prices this result also implies the non substitution theorem for the neoclassical dynamic model of sustained growth optimal input profiles relative prices and interest rates are asymptotically independent of intertemporal preferences

transactions that did not happen and their influence on prices abstract this paper studies data from the wholesale fruit and vegetables market in marseille we have details of counteroffers to the prices that were proposed by the seller even when no transaction took place we analyse the evolution of prices and the relation between the final price struck and the proposals of the two parties periods with no buyer refusals of offers or bargaining with no transaction will lead to a revision of the seller s first price more importantly the sharing of the surplus moves in the buyer s favour during the day these theoretical predictions are confirmed by our data set

turnpike theorems in nonconvex nonstationary environments this paper provides a comprehensive development of turnpike theory in a stochastic aggregative model with time varying nonconvex technology a new approach to turnpike theorems is developed that exploits the monotonicity of optimal programs and utilizes a supermartingale process generated by stochastic euler equations this extends the classical turnpike theory to general nonconvex nonstationary environments copyright 1997 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

identification of endogenous social effects the reflection problem this paper examines the reflection problem that arises when a researcher observing the distribution of behaviour in a population tries to infer whether the average behaviour in some group influences the behaviour of the individuals that comprise the group it is found that inference is not possible unless the researcher has prior information specifying the compisition of reference groups if this information is available the prospects for inference depend critically on the population relationship between the variables defining reference groups and those directly affecting outcomes inference is difficult to implossible if these variables are functionally dependent or are statistically independent the prospects are better if the variables defining reference groups and those directly affecting outcomes are moderately related in the population

the social multiplier aggregate data is often used to make inferences about individual level behavior if there are social interactions in which one person s actions influence his neighbor s incentives or information then these inferences are inappropriate the presence of positive social interactions or strategic complementarities implies the existence of a social multiplier where aggregate relationships will overstate individual elasticities we present a brief model and then estimate the size of the social multiplier in three areas the impact of education on wages the impact of demographics on crime and group membership among dartmouth roommates in these contexts there is a significant social multiplier jel ho jo co

equipment prices human capital and economic growth abstract this paper presents a multisectoral model of economic growth in which endogenous technological progress is embodied in new equipment capital the difference in the intensity of use of human capital across sectors creates aggregate dynamic non convexities and hence the model may generate multiple balanced growth paths under standard parameter values our model can explain the observed correlations found for a pool of countries between investment rates in equipment capital and income growth on the one hand and between the rate of decline in equipment prices and income growth on the other the model is then used to study the effectiveness of two public policies that have been widely implemented to promote economic growth an equipment investment tax credit and a tax incentive to human capital accumulation our results indicate that both policies have positive effects on equipment investment and on long run growth

a strategic model of social and economic networks we study the stability and efficiency of social and economic networks when self interested individuals can form or sever links first for two stylized models we characterize the stable and efficient networks there does not always exist a stable network that is efficient next we show that this tension persists generally to assure that there exists a stable network that is efficient one is forced to allocate resources to nodes that are not responsible for any of the production we characterize one such allocation rule the equal split rule and another rule that arises naturally from bargaining of the players

dynamic interaction models of economic equilibrium abstract the paper develops a stochastic dynamic model of economic equilibrium with locally interacting agents the main focus of the study is on the modeling of market interactions those arising in connection with commodity exchange and regulated by price mechanisms the mathematical framework is a control theory for random vector fields on directed graphs the graphs involved serve to describe the spatio temporal structure of commodity flows in the system the main results are concerned with the existence uniqueness and stability of stochastic dynamic equilibria

welfare and sustainability effects of dietary recommendations the paper develops a framework combining a model of rational behaviour under dietary constraints an epidemiological model of diet related mortality and a life cycle analysis model of environmental impact which permits the ex ante assessment of dietary recommendations in multiple sustainability dimensions i e taste cost welfare effect deaths avoided reductions in greenhouse gas emissions and acidification it is applied to compare in a french context the relative effects and efficiency of six popular sustainable diet recommendations the results confirm the synergies between the health and environmental dimensions healthy eating recommendations usually have a positive effect on the environment although some exceptions exist most of the sustainable diet recommendations appear highly cost effective but those most commonly promoted on health grounds e g targeting consumption of salt fruits and vegetables and saturated fat rank highest in terms of overall efficiency moreover the valuation of benefits indicates that in most cases health benefits are significantly larger than environmental benefits overall the analysis reveals some under investment in the promotion of sustainable diet recommendations in france the general lack of enthusiasm in policy circles for informational measures promoting behavioural change may reflect unrealistic expectations about the speed and magnitude of dietary change rather than an objective assessment of the efficiency of those measures

what s that got to do with the price of fish buyers behavior on the ancona fish market abstract in this paper we analyze the ancona wholesale fish market meritan where transactions take place in three simultaneous dutch auctions our objective is to characterize the behavior of market participants and in particular that of buyers in such a market structure our analysis shows that buyer seller relationships are less important than in a pairwise bargaining market such as the marseille fish market but that a significant amount of loyalty is still present under the auction mechanism we provide an explanation of the declining price paradox for the fish market of ancona by linking the rule used by the buyers to set their bid to the relationship between the variation in the price of the last transactions in the day and the quantity of fish available on that day in fact the average price tends to increase for the last transactions on days characterized by a limited supply of fish

information and advertising the case of fat consumption in the united states the role of information in markets has become a mainstay of the economics literature theoretical work has focused on the market effects of asymmetric information and costly search incentives for voluntary disclosure contracting and other market and policy solutions to information issues see michael katz 1989 and joseph stiglitz 1989 for recent reviews and on how consumers ability to use information could affect market outcomes as in the recent work on information cascades e g sushil bikhchandani et al 1992 the empirical literature testing informational theories is more limited in large part because the key variable of interest information is so difficult to measure most of the literature relies on indirect tests usually based on regulatory differences as in the study of state restrictions on advertising for eyeglasses lee benham 1972 or on new information or public education campaigns typified by the studies of smoking see w kip viscusi 1992 for a recent summary other studies examine cross sectional differences in behavior in an effort to assess whether human capital or other individual or household differences are important in explaining responses to evolving information this paper follows these traditions specifically this study examines changes in fat and saturated fat consumption in the united states as information spread connecting these lipids to heart disease and cancer risks 1 the study examines changes in consumption during two regulatory regimes the years 1977 1985 when government and general information sources continued their efforts to educate the public about the links between fats and disease risks and when producers were free to label these characteristics on food packages and in advertising and the years 1985 1990 when the regulatory ban was lifted that prohibited producers from explaining the reasons why consumers should be interested in the content of foods this controversial regulatory change allowed the use of so called health claims in labeling and advertising subject to the normal deception rules for all advertising and labeling claims 2 comparison of these two periods allows us to provide evidence on whether and how consumers reacted to the general flow of information prior to 1985 and whether advertising appears to have added information to the market or as many critics believe provided deceptive or sufficiently incomplete information to undermine public education efforts

global water crisis and future food security in an era of climate change food policy should serve humanity by advancing the humane goals of eradicating extreme poverty and hunger however these goals have recently been challenged by emerging forces including climate change water scarcity the energy crisis as well as the credit crisis this paper analyses the overall role of these forces and population growth in redefining global food security specifically global water supply and demand as well as the linkages between water supply and food security are examined the analysis reveals that the water for food security situation is intricate and might get daunting if no action is taken investments are needed today for enhancing future food security this requires action on several fronts including tackling climate change preserving land and conserving water reducing the energy footprint in food systems developing and adopting climate resilient varieties modernising irrigation infrastructure shoring up domestic food supplies reforming international food trade and responding to other global challenges

some stochastic processes of interdependent demand and technological diffusion of an innovation exhibiting externalities among adopters one frequently hears the opinion that as twentieth century society becomes more complex technological change assumes more significance and occurs at a more r apid pace investment in researclh and development results in a myriad of potential innovations yet as the frontiers of technology are plshed outward uncertainity about the usefulniess of innovations becomes an increasingly important factor in the decision whether or not to adopt the new innovation furthermore the decisions of individual economic agents tend to become increasingly interrelated many recent innovations are such that whether others adopt the device influences the benefits of adoption which accrue to a given consumer or firm such externalities may be positive for example consider a nation s decision to use the metric system the wearing of a style by a fashion leader a merchant s decision to accept a certain credit card or the purchase of a coinmunication device by someone with whom one desires to communicate or negative for instance imitation in the production of a faddish consumption item for which the potential market is limited or the pulrchase of a telephone by an obscene caller our goal is to analyze techn ological difflsioll with interdependencies when uncertainty and informational considerationis are an inherent part of the theoretical model the uncertainty may be of two types a technological ulncertainty the usefulness or quality of the innovation is at least partially unlknown and b adoption uncertainity incomplete or inaccurate knowledge about who is usinlg the innovation in our stochastic model adoptioni is reversible the decision to use the innovation is not permanent but rather agents may change their minds agents are not able to learn about the characteristics quality profitability usefulness etc of the innovation this assumption limits the applicability of

food choice health information and functional ingredients an experimental auction employing bread abstract in this paper we present the results of an experimental auction conducted to examine the influence of health and nutritional information on food choice and in particular estimate consumer willingness to pay wtp for bread that contains functional ingredients employing a sandwich we find that consumers are wtp more for a whole grain and whole grain granary bread sandwich than other bread types including white bread that contains a functional ingredient we also find that consumers react positively to the provision of nutritional and health benefit information but that this effect occurs regardless of whether we supply specific or non specific health benefit information we discuss information provision and health policy implications that emerge from our analysis for bread products in the sandwich market

network structure and the diffusion of knowledge this paper models knowledge diffusion as a barter process in which agents exchange different types of knowledge this is intended to capture the observed practice of informal knowledge trading agents are located on a network and are directly connected with a small number of other agents agents repeatedly meet those with whom direct connections exist and trade if mutually profitable trades exist in this way knowledge diffuses throughout the economy we examine the relationship between network architecture and diffusion performance we consider the space of structures that fall between at one extreme a network in which every agent is connected to n nearest neighbours and at the other extreme a network with each agent being connected to on average n randomly chosen agents we find that the performance of the system exhibits clear small world properties in that the steady state level of average knowledge is maximal when the structure is a small world that is when most connections are local but roughly 10 percent of them are long distance the variance of knowledge levels among agents is maximal in the small world region whereas the coefficient of variation is minimal we explain these results as reflecting the dynamics of knowledge transmission as affected by the architecture of connections among agents

implementation of walrasian expectations equilibria in an exchange economy with differentially informed traders non exclusivity of information nei is the condition that each trader s private information be perfectly predictable by an outside observer who has observed the private information of all other traders nei is one of a set of conditions which taken together are sufficient for the implementability of fully revealing expectations equilibria here we show that this condition is in fact necessary for the weak implementation of a much broader class of walrasian equilibria herein called expectations equilibria

on bayesian implementable allocations this paper identifies several social choice correspondences which are and are not fully implementable in economic environments when agents are incompletely informed about the environment we show that in contrast to results in the case of complete information neither efficient allocations nor core allocations define implementable social choice correspondences we also identify conditions under which the rational expectations equilibrium correspondence is implementable we extend the concepts of fair allocations and lindahl allocations to economies with incomplete information and show that envy free allocations and lindahl allocations are implementable under some conditions while fair allocations are not

rationalizability learning and equilibrium in games with strategic complementarities we study a rich class of noncooperative games that includes models of oligopoly competition macroeconomic coordination failures arms races bank runs technology adoption and diffusion r d competition pretrial bargaining coordination in teams and many others for all these games the sets of pure strategy nash equilibria correlated equilibria and rationalizable strategies have identical bounds also for a class of models of dynamic adaptive choice behavior that encompasses both best response dynamics and bayesian learning the players choices lie eventually within the same bounds these bounds are shown to vary monotonically with certain exogenous parameters we study the class of noncooperative supermodular games introduced by topkis 1979 and further analyzed by vives 1985 1989 who also pointed out the importance of these games in industrial economics supermodular games are games in which each player s strategy set is partially ordered the marginal returns to increasing one s strategy rise with increases in the competitors strategies so that the game exhibits strategic complementarity 2 and if a player s strategies are multidimensional marginal returns to any one com ponent of the player s strategy rise with increases in the other components this class turns out to encompass many of the most important economic applications of noncooperative game theory in macroeconomics diamond s 1982 search model and bryant s 1983 1984 rational expectations models can be represented as supermodular games in each of these models more activity by some members of the economy raises the returns to increased levels of activity by others in oligopoly theory some models of bertrand oligopoly with differentiated products qualify as supermodu lar games in these games when a firm s competitors raise their prices the marginal profitability of the firm s own price increase rises a similar structure is present in games of new technology adoption such as those of dybvig and spatt 1983 farrell and saloner 1986 and katz and shapiro 1986 when more users hook into a communication system or more manufacturers adopt an interface standard the marginal return to others of doing the same often rises similarly in some specifications of the bank runs model introduced by diamond and dybvig 1983 when more depositors withdraw their funds from a bank it is more worthwhile for other depositors to do the same in the warrant exercise

on income fluctuations and capital gains with a convex production function abstract this work considers a one good economy the production function is random and not necessarily concave the interest factor is variable and the consumer must maximize asymptotically the expected accumulated and discounted utility one proves that the value function is concave and the limit policy is optimal and is the unique one furthermore if the production function is convex there exist two levels of capital with the property that for initial capitals below the first level the optimal sequence of capitals stays bounded with probability one for initial capitals above the second level the optimal sequence of capitals tends monotonically to infinity for initial capitals between the two levels the optimal sequence of capitals leaves the interval with probability one

dynamic efficiency of conservation of renewable resources under uncertainty abstract we examine the efficiency of conservation of a renewable resource whose natural productivity is influenced by random environmental disturbances we allow for non concave biological production and stock dependent social welfare unlike deterministic models conservation may be inefficient no matter how productive the resource growth function is in addition improvements in the natural productivity of the resource might increase the possibility of extinction we characterize the conditions on social welfare resource growth the discount rate and the distribution of environmental disturbances that are sufficient for conservation to be efficient the productivity of the resource under the worst possible environmental conditions the discount rate and the welfare function are all crucial factors in determining the efficiency of conservation journal of economic literature classification numbers q20 o41 d90

food product composition consumer health and public policy introduction and overview of special section as efforts to improve diets in high income countries intensify attention has turned to how policies may influence diet composition the case studies in this special issue contribute to our understanding of how two main types of policies have influenced food product composition and dietary outcomes 1 policies affecting food manufacturers input costs and 2 information policy affecting competition research on the first type of policy is relatively new but suggests that us commodity policies would not be good policy instruments to influence diets except through the long run impacts of agricultural research research on the impacts of information policy continues to demonstrate that it can spur food industry competition to introduce healthier products but may not result in healthier diets international comparisons show where the us experience may have relevance for other high income countries

uneven growth a framework for research in development economics the textbook paradigm of economy wide development rests on the premise of balanced growth that is on the presumption that all sectors will grow in unison over time as a country gets richer this view has served us reasonably well in some circumstances but is not particularly useful for accounts of modern under development in many developing countries economic growth has been fundamentally uneven software development the outsourcing of services sectoral technological change quick compositional shifts between agriculture and other sectors the rise of particular exports special economic zones and so on this paper will discuss both the sources of uneven growth and its implications with greater emphasis on the latter the paper will argue that much of the distributional issues or the reactions to globalization that we see in modern developing societies can be viewed as reactions to a growth process that is fundamentally uneven and is indeed perceived as such