hybrid r d we develop a model of r d collaboration in which individual firms carry out in house research on core activities and undertake bilateral joint projects on non core activities with other firms we develop conditions on the profit functions of the firm under which r d investments in different projects of a firm are complementary we show that this condition is met by standard price and quantity setting oligopoly models we then study the relation between the number of joint projects and investments and profits in this context we identify a second aspect of complementarity equilibrium investments in in house as well as in each joint project are increasing in the number of projects however we find that an increase in number of joint projects of all firms lowers collective profits suggesting the presence of excessive incentives for conducting research

learning about a new technology pineapple in ghana this paper investigates the role of social learning in the diffusion of a new agri cultural technology in ghana we use unique data on farmers communication patterns to define each individual s information neighborhood conditional on many potentially confounding variables we find evidence that farmers adjust their inputs to align with those of their information neighbors who were surpris ingly successful in previous periods the relationship of these input adjustments to experience further indicates the presence of social learning in addition applying the same method to input choices for another crop of known technol ogy correctly indicates an absence of social learning effects jel d83 013 033 q16

co creation with production externalities co creation the participation of customers in the design and production of goods and services has been gaining popularity in recent years in this research we incorporate firm pricing into the joint production process allowing us to study 1 production externalities between firm and customers 2 production externalities among customers and 3 optimal pricing by firms we show that given a choice a monopoly firm will opt for co creation with customers rather than deal with passive price taking consumers furthermore the firm will increase the effort it devotes to co creation as the number of potential co creating customers increases we show that the profit of a firm facing a centralized pattern of externalities among customers with an expert or lead user in the center can be higher than its profit when facing a decentralized pattern of externalities among customers and clearly dominates its profit when customers do not have any cross externalities thus we provide a different justification for the use of lead users one that depends on their network centrality and not on having lower cost more information or greater ability than the firm because the decentralized pattern has more links than the centralized pattern our results demonstrate the importance of the pattern of links between customers and not just their number in determining the profitability of co creation furthermore we find that the lead user s externality spillover to other connected users her neighbors acts as a force multiplier on the efforts exerted by all participants in equilibrium specifically a higher spillover from the lead user increases the efforts of the firm the neighbors and the lead user herself and this may lead to beneficial outcomes for all finally we show that in co creation environments a monopolist firm may benefit by committing to a single price rather than exercising price discrimination this is because the pricing structure affects customers incentive to invest effort in the innovation production stage

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

tax evasion on a social network abstract we relate tax evasion behavior to a substantial literature on social comparison in judgements taxpayers engage in tax evasion as a means to boost their expected consumption relative to others in their social network the unique nash equilibrium of the model relates optimal evasion to a bonacich measure of network centrality more central taxpayers evade more given that tax authorities are now investing heavily in big data tools that aim to construct social networks we investigate the value of acquiring network information we do this using networks that allow for celebrity taxpayers whose consumption is seen widely and who are systematically of higher wealth we show that there are pronounced returns to the initial acquisition of network information especially in the presence of celebrity taxpayers

public goods in networks this paper considers incentives to provide goods that are non excludable along social or geographic links we find first that networks can lead to specialization in public good provision in every social network there is an equilibrium where some individuals contribute and others free ride in many networks this extreme is the only outcome second specialization can benefit society as a whole this outcome arises when contributors are linked collectively to many agents finally a new link increases access to public goods but reduces individual incentives to contribute hence overall welfare can be higher when there are holes in a network

trading in networks theory and experiments intermediation is a prominent feature of economic production and exchange two features of intermediation are salient coordination among traders between the source and the destination and competition between alternative combinations of intermediaries we develop a simple model to study these forces and we test the theoretical predictions in experiments our theoretical analysis yields a complete characterization of pricing equilibrium in networks there exist both ecient and inecient equilibria suggesting a key role of coordination among intermediaries strategic interaction leads to either buyer and seller retaining all surplus or intermediaries extracting all surplus we develop conditions on network structure under which these di erent extremal outcomes arise respectively laboratory experiments show that eciency prevails in almost all cases so traders are successful in coordination subjects coordinate on extreme surplus division finally experiments highlight the role of network structure in determining pricing and the

private provision of public goods and information diffusion in social groups i describe a dynamic model of costly information sharing where private information affecting collective value actions is transmitted by social proximity individuals make voluntary contributions toward the provision of a pure public good and information transmission about quality of provision is a necessary condition for collective provision to take place in a stationary equilibrium i show that unlike in the case of private goods better informed individuals face positive incentives to incur a cost to share information with their neighbors and that these incentives are stronger and provision of the pure public good greater the smaller are individuals social neighborhoods

network structure and strategic investments an experimental analysis abstract this paper experimentally analyzes the effect of network structures on individuals decisions in a game of strategic substitutes the theoretical basis for our experiment is the model of bramoulle and kranton 2007 as predicted we find that individuals are able to coordinate on equilibria but that coordination strongly depends on the network structure despite frequent coordination failures in graphs of size n 4 equilibrium play seems easier on network architectures with high low density and low high centrality if play converges it almost exclusively does so towards the predicted equilibria theoretical results with respect to welfare are also confirmed next to global graph structural properties we also explore the effects of local and individual factors we find that behavior on networks is affected by the number of direct neighbors but not by individuals risk attitudes apparently the global and the local structure of a network does not leave much explanatory room for individual effects that pertain to risk taking

social capital access and entrepreneurship we investigate the effect of social capital access on entrepreneurship social capital helps entrepreneurs to overcome resource constraints this is especially important in small communities where we often see a lack of market oriented institutions such as venture capital firms entrepreneurs gain access to social capital via club memberships combining differences in the number of individual club memberships with differences in the importance of social capital across communities we identify a causal small community mark up effect of individual club memberships on entrepreneurship assuming that unobserved heterogeneity that might influence both the individual s selection into clubs and the occupational choice to be an entrepreneur is independent of community size we find that the effect of club membership on the propensity to be an entrepreneur is 2 6 percentage points larger in small communities than in large communities robustness tests support the validity of our identifying assumption and results

learning by doing and learning from others human capital and technical change in agriculture household level panel data from a nationally representative sample of rural indian households describing the adoption and profitability of high yielding seed varieties hyvs associated with the green revolution are used to test the implications of a model incorporating learning by doing and learning spillovers the estimates indicate that i imperfect knowledge about the management of the new seeds was a significant barrier to adoption ii this barrier diminished as farmer experience with the new technologies increased iii own experience and neighbors experience with hyvs significantly increased hyv profitability and iv farmers do not fully incorporate the village returns to learning in making adoption decisions

a theory of buyer seller networks this paper introduces a new model of exchange networks rather than markets of buyers and sellers it begins with the empirically motivated premise that a buyer and seller must have a relationship a link to exchange goods networks buyers sellers and the pattern of links connecting them are common exchange environments this paper develops a methodology to study network structures and explains why agents may form networks in a model that captures characteristics of a variety of industries the paper shows that buyers and sellers acting strategically in their own self interests can form the network structures that maximize overall welfare

learning from neighbours when payoffs from different actions are unknown agents use their own past experience as well as the experience of their neighbours to guide their decision making in this paper we develop a general framework to study the relationship between the structure of these neighbourhoods and the process of social learning we show that in a connected society local learning ensures that all agents obtain the same payoffs in the long run thus if actions have different payoffs then all agents choose the same action and social conformism obtains we develop conditions on the distribution of prior beliefs the structure of neighbourhoods and the informativeness of actions under which this action is optimal in particular we identify a property of neighbourhood structures local independencewhich greatly facilitates social learning simulations of the model generate spatial and temporal patterns of adoption that are consistent with empirical work

endogenous peer effects local aggregate or local average a b s t r a c t we develop a unified model embedding different behavioral mechanisms of social interac tions and design a statistical model selection test to differentiate between them in empirical applications this framework is applied to study peer effects in education effort in study ing and sport activities for adolescents in the united states we find that for education students tend to conform to the social norm of their friends while for sport activities both the social multiplier and the social norm effect matter

r d networks we develop a model of strategic networks that captures two distinctive features of interfirm collaboration bilateral agreements and nonexclusive relationships our analysis highlights the relationship between market competition firms incentives to invest in r d and the architecture of collaboration networks in the absence of firm rivalry the complete network where each firm collaborates with all others is uniquely stable industry profit maximizing and efficient by contrast under strong market rivalry the complete network is stable but intermediate levels of collaboration and asymmetric networks are more attractive from a collective viewpoint this suggests that competing firms may have excessive incentives to form collaborative links

social networks and non market valuations this paper considers the role of social networks in the non market valuation of public goods in the model individuals derive utility both from their own direct enjoyment of the public good and from the enjoyment of those in their network we find that network structure almost always matters both for utility and for valuation the network increases aggregate valuation when it assigns higher importance that is stronger connections to individuals with higher private values for the public good the model provides a theoretical foundation for the idea of opinion leaders who have disproportionate influence over their communities specifically opinion leaders are individuals assigned high importance by the network and projects favored by opinion leaders tend to be favored by the network as a whole the model can also guide future empirical studies by enabling a more structural approach to non market valuation in a socially connected group

learning from the behavior of others conformity fads and informational cascades learning by observing the past decisions of others can help explain some otherwise puzzling phenomena about human behavior for example why do people tend to converge on similar behavior why is mass behavior prone to error and fads the authors argue that the theory of observational learning and particularly of informational cascades has much to offer economics business strategy political science and the study of criminal behavior

cooperation with network monitoring this paper studies the maximum level of cooperation that can be sustained in perfect bayesian equilibrium in repeated games with network monitoring where players observe each other s actions either perfectly or not at all the foundational result is that the maximum level of cooperation can be robustly sustained in grim trigger strategies if players are equally well monitored comparative statics on the maximum level of cooperation are highly tractable

sanctions in networks the most unkindest cut of all the extensive literature on sanctions has mainly focused on a dyadic interaction between sender and target in contrast this paper examines sanctions when the sender and target are embedded in a network of linkages to other agents the sender can assemble a sanctioning coalition of neighbors to sever their links execute multi link cuts to the target and her allies efficacy of sanctions is now crucially dependent on the network architecture we characterize the structural properties of networks in which a sender can effectively sanction a target in the short run when links can only be deleted and the long run when links can be both deleted and added

strong and weak links many of the interesting issues in the economics of networks information transmission individual incentives with local externalities investments in connections and the structure of complex networks have to do with the quality of links between individuals entities however most of the research to date has assumed a one zero formulation of connections i argue that it is possible to write down tractable models of quality of links and that analyzing such models yields fresh insights into these issues jel c72 d85 z13

the origins of the canadian wheat boom 1880 1910 completion of the canadian pacific railway was expected to initiate a rush of settlement yet the wheat boom did not materialize until about fifteen years later in addition to causes of the delay already identified this paper proposes another factor the inability of early settlers to cultivate more than a small area of land the paper analyzes reasons for the small sizes of early farms and for their subsequent growth and estimates farm profitability before and after the delay to show how climate and technology affected early prairie farming completion of the canadian pacific railway was expected to initiate a rush of settlement yet the wheat boom did not materialize until about fifteen years later in addition to causes of the delay already identified this paper proposes another factor the inability of early settlers to cultivate more than a small area of land the paper analyses reasons for the small sizes of early farms and for their subsequent growth and estimates farm profitability before and after the delay to show how climate and technology affected early prairie farming

social norms in networks abstract although the linear in means model is the workhorse model in empirical work on peer effects its theoretical properties are understudied in this study we develop a social norm model that provides a microfoundation of the linear in means model and investigate its properties we show that individual outcomes may increase decrease or vary non monotonically with the taste for conformity equilibria are usually inefficient and to restore the first best the planner needs to subsidize tax agents whose neighbors make efforts above below the social norms thus giving more subsidies to more central agents is not necessarily efficient we also discuss the policy implications of our model in terms of education and crime

comparing the welfare costs and initial dynamics of alternative inflation stabilization policies abstract this paper uses calibrated versions of a sticky price currency substitution model to compare the initial dynamics and welfare costs of three types of stabilization program exchange rate based erb money based mb and money based with initial reliquefication mbr erb and mbr programs are found to induce an initial expansion in real activity whereas mb programs are initially contractionary the welfare gains of eliminating high inflation are significant under permanent erb and mbr programs but small under permanent mb programs in addition temporary mb programs are shown to be much more disruptive than temporary erb or mbr programs these results provide an explanation for why mb programs are so rarely implemented and suggest that empirical studies that fail to distinguish mb from mbr programs are likely to be biased toward finding that stabilizations are always expansionary regardless of the nominal anchor

anti coordination and social interactions abstract this paper studies the first model of social interactions with anti coordination agents have fixed partners with whom they play a common bilateral game of anti coordination like the chicken game partnerships are represented as links of a network the paper asks how do social interactions interplay with the incentives to anti coordinate how does the social network affect individual choices in equilibrium the analysis shows that network effects are much stronger than when partners play a coordination game the network notably affects how agents respond when a strategy becomes more advantageous in the standard benchmark of complete interactions more agents play the strategy this result does not generally hold when the network is incomplete on bipartite networks agents choices are unaffected while on core periphery networks less agents may play the strategy

the effects of social networks on employment and inequality we develop a model where agents obtain information about job opportunities through an explicitly modeled network of social contacts we show that employment is positively correlated across time and agents moreover unemployment exhibits duration dependence the probability of obtaining a job decreases in the length of time that an agent has been unemployed finally we examine inequality between two groups if staying in the labor market is costly and one group starts with a worse employment status then that group s drop out rate will be higher and their employment prospects will be persistently below that of the other group

the cost of segregation in social networks abstract this paper investigates the welfare effect of income redistribution in the private provision of public goods on networks we first show that the welfare effect of income redistribution is determined by bonacich centrality then we develop an index based on the network structure of interactions which roughly speaking measures the welfare effect of income redistribution confined to a component of contributors the proposed index vanishes when applied to large components of contributors that display special segregated interactions which suggests an asymptotic neutrality of redistributive policies

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

experimental games on networks underpinnings of behavior and equilibrium selection in this paper we describe a series of laboratory experiments that implement specific examples of a general network structure specifically actions are either strategic substitutes or strategic complements and participants have either complete or incomplete information about the structure of a random network since economic environments typically have a considerable degree of complementarity or substitutability this framework applies to a wide variety of settings we examine behavior and equilibrium selection the degree of equilibrium play is striking in particular with incomplete information behavior closely resembles the theoretical equilibrium whenever this is unique when there are multiple equilibria general features of networks such as connectivity clustering and the degree of the players help to predict informed behavior in the lab people appear to be strongly attracted to maximizing aggregate payoffs social efficiency but there are forces that moderate this attraction 1 people seem content with in the aggregate capturing only the lion s share of the efficient profits in exchange for reduced exposure to loss and 2 uncertainty about the network structure makes it considerably more difficult to coordinate on a demanding but efficient equilibrium that is typically implemented with complete information

network effects on strategic interactions a laboratory approach abstract we examine the effect of interaction structure network on two classes of collective activities herding and shirking respectively referring to the situation where a player s incentive to take a certain action increases and decreases if more of her network neighbors follow the same action in our experiment we find that subjects do not act according to theoretical equilibrium and their frequencies of making the socially beneficial choice in herding and shirking games are inversely influenced by the number of network neighbors they have moreover the observed local network effect is stronger in shirking games while the global network effect is more significantly present in herding games we explain the behavioral regularities through a hybrid learning model which extends sewa learning into a network context as such our learning model provides a foundation for the observed dynamics disequilibrium behavior as well as the local and global network effects