r d investments under endogenous cluster formation abstract we provide an innovative theory based explanation for the positive relationship between firms r d intensity and their degree of r d cooperation we show that when oligopolistic firms decide on long term r d investment before forming research clusters among competitors investment incentives are increased by the desire to become a member of an attractive cluster this can result in over investment compared to the welfare optimum and compared to a scenario where research clusters are ex ante fixed thereby as a theoretical contribution we fully characterize the equilibria of the unanimity game on cluster formation with heterogeneous firms

changes in labor force composition and male earnings a production approach models of aggregate production are estimated and used to investigate the effects of changes in labor force composition on the recently observed decline in the earnings of college graduates relative to other workers and on the fall in the earnings of younger workers relative to older workers changes in labor force composition explain substantial proportions of these observed earnings changes the most important compositional change appears to have been the rapid increase in the number of young male college graduates projections outside the sample are consistent with depressed earnings throughout the lifetimes of the large baby boom cohorts especially among college graduates but do not suggest that depressed college graduate earnings are a permanent phenomenon for all birth cohorts

earnings inequality among males in the united states trends and the effect of labor force growth we analyze the variance of log earnings within labor force cohorts of u s males with particular attention to the influence of labor force growth rates estimates with data from the 1968 79 current population surveys reveal increases in earnings inequality within labor force cohorts even after we control for the level of education experience and unemployment a model of human capital investment is used to analyze differences among cohorts in the life cycle profile of the variance of log earnings it is shown that a pattern of sharply increasing and then declining labor force growth rates will tend to raise the return on human capital investment and thereby increase the variance of postschooling investment and log earnings early in the life cycle this positive effect on relative earnings inequality should decline with experience and possibly become negative because of the post world war ii baby boom and baby bust recent labor force entrants have faced just such a pattern of actual and projected labor

cooperative and noncooperative r d in duopoly with spillovers contrary to the usual assumption made in most oligopoly models relations among firms are seldom of a wholly cooperative or noncooperative type in many situations they compete in some fields while they cooperate in others an important example is the case of cooperative research efforts bringing fierce competitors together two types of agreement are observed first r d cooperation can take place at the so called precompetitive stage companies share basic information and efforts in the r d stage but remain rivals in the market place 1 a second type of agreement involves an extended collusion between partners creating common policies at the product level the usual justifications of this extension are the difficulties of protecting intellectual property the idea is then to allow partners who have achieved inventions together to also control together the processes and products which embody the results of their collaboration in order to recuperate jointly their r d investments 2 what could be expected from these types of agreement is a reduction in r d expenditures because of less wasteful duplication and a reduction of total production because of more reprinted from the american economic review 78 5 1133 1137 1988 center for operations research econometrics 1348 louvain la neuve belgium we are grateful to jean

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

networking off madison avenue known for the key role that networking plays in the operation of agencies where interviews suggest that informal networking among close neighbors is critical to many agencies success networking involves the exchange of ideas and while there is no market place for these ideas exchanges may be more deliberate rather than just marshall s 1890 mysteries of the air type of information spillovers this paper examines the effect on productivity of having more near advertising agency neighborhoods and hence better opportunities for meetings and exchange within manhattan we will show that there is extremely rapid spatial decay in the benefits of having more near neighbors even in the close quarters of southern manhattan a finding that is new to the empirical literature and indicates our understanding of scale externalities is still very limited the finding indicates that having a high density of commercial establishments is important in enhancing local productivity an issue in lucas and rossi hansberg 2002 where within business district spatial decay of spillovers plays a key role we will argue also that in manhattan advertising agencies trade off the higher rent costs of being in bigger clusters nearer centers of action against the lower rent costs of operating on the fringes away from high concentrations of other agencies introducing the idea of trade offs immediately suggests heterogeneity is involved we will show that higher quality agencies are the ones willing to pay more rent to locate in greater size clusters specifically because they benefit more from networking while all 1 the research in this paper was conducted while the authors were census bureau research associates at the boston research data center research results and conclusions expressed are those of the authors and do not necessarily indicate concurrence by the census bureau the paper has been screened to ensure that no confidential data are revealed we acknowledge helpful comments from andrew foster on aspects of the paper and from participants in seminars at brown university lse and the university of toronto

on implicit forms of multiproduct multifactor production functions a quest for generality in economic analysis appears to underlie the long tradition of the use of implicit functions however insufficient attention is given to weaknesses and limitations of implicit functions as they are traditionally used e g cohen and cyert hadar henderson and quandt malinvaud naylor naylor and vernon and samuelson among others careless use of implicit functions can result in faulty analysis in particular clarification of these limitations is needed especially as they pertain to the study of multiproduct multifactor mp mf production processes this paper is a rigorous examination of certain issues regarding implicit functions and mp mf production processes because any relation that explicitly determines one argument as a function of the remaining arguments can be written in implicit function form our results also apply to explicit function representations of mp mf production the functions examined here are continuously differentiable and can be used as production feasibility constraints in a lagrangian or kuhn tucker analysis of the mp mf firm the theory of mp mf production is relevant in the conceptualization of resource allocation problems throughout agriculture for example few important real world analyses of agricultural production or marketing operations are single product in nature in fact in his extensive literature review on production efficiency in agricultural processing and marketing french states multiple outputs are effectively the rule rather than the exception similarly mp mf theory is prominent in the study of environmental and natural resource problems involving technological externalities despite the importance of the theory it appears that work to date is a collection of special cases of a potentially more general theory it is our hope that this paper will stimulate a reexamination of mp mf production theory

survey attrition and schooling choices we use data from three cohorts of the national longitudinal surveys of labor market experience and from the panel study of income dynamics to study the effect of survey attrition on estimates of statistical models of schooling choices we estimate regressions using data on people who always respond to the surveys stayers and on people who miss some surveys attritors and test whether the same statistical model describes the behavior of stayers and attritors in general with a few exceptions we find that attrition either has no effect on the regression estimates or only affects the estimates of the intercept and sometimes the coefficients of birth year dummies and does not affect estimates of family background slope coefficients

endogenous structures of association in oligopolies the formulation of associations of firms in an oligopoly with linear demand is analyzed as a two stage noncooperative game in the first stage firms form associations in order to decrease their costs and in the second stage they compete on the market examples of associations include r d joint ventures and groups of firms adopting common standards in equilibrium the associations formed exhibit two general features they are asymmetric and inefficient

the effect of entry on r d networks we investigate the effect of potential entry on the formation and stability of r d networks considering farsighted firms we show that the presence of a potential entrant often alters the incentives of incumbent firms to establish an r d link in particular incumbent firms may choose to form an otherwise undesirable r d collaboration in order to deter the entry of a new firm moreover an incumbent firm may refrain from establishing an otherwise desirable r d collaboration expecting to form a more profitable r d link with the entrant finally potential entry may lead an inefficient incumbent to exit the market we also perform a welfare analysisand show that market and societal incentives are often misaligned

labor market competition among youths white women and others we estimate substitution possibilities among a set of age race sex groups in the labor force the estimates are based on cross section data from smsas in 1969 and they allow us to consider how substitutable adult women are for young women or young men the estimates are used along with assumptions about the extent of wage rigidity and elasticities of labor supply to simulate the direct and indirect effects of the growth of the female labor force on job opportunities for youth assuming rigid wages for young workers and on the wage rates of adult males assuming these wages are flexible this abstract was borrowed from another version of this item

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

race and human capital while human capital has been used with some success to analyze recent changes in racial income differences scholars have repeatedly pointed to a major empirical problem that appears to severely limit the historical relevanlce and scope of skill based theories as applied to racial questions the challenge they raise is legitimate put simply if measured skill disparities between the races narrowed throughout the twentieth century why did income ratios first begin to converge in the 1960 s in this paper i address this question relying on some unexploited census data by race on education literacy occupations and income using these data that begin with the 1890 census i present new estimates of agespecific relative income positions of black men for all postslavery birth cohorts in addition to reconciling the apparently inconsistent skill and income series these income ratios offer a very different historical record than many economists believe to have been the case to cite a prominent example gunnar myrdal s classic work 1944 saw the economic position of his contemporary black america not only as dismal but made even more so by its sense of hopelessness given the absence of any hint of progress or change while myrdal s pessimism is understandable it appears that even in his day seeds had long been sown that were already permanently altering and improving the relative economic status of black men

schooling choices and demographic cycles this paper examines the effect of demographic cycles on schooling choices and the timing of school completion utilizing data from the u s national longitudinal surveys of labor market experience and from the panel study of income dynamics we find that men and women born during the upswing of a demographic cycle obtain more schooling and take longer to finish a year of schooling than comparable individuals born during the downswing of a demographic cycle the patterns that we document are more complex than would be predicted by any of the theoretical models of educational responses to demographic cycles that have been presented in the literature excerpt

the demographic cycle and optimal schooling choices a model is developed that enables the authors to estimate the effects of demographic cycles on both earnings and schooling the model is tested using data from the 1991 korean occupational wage survey the results indicate that cohorts following large birth cohorts in the cycle choose relatively less formal schooling compared to pre peak cohorts and that post peak cohorts also have lower incomes this result concerning south korea is consistent with findings from previous studies concerning the united states annotation

farsighted r d networks we analyze the formation of bilateral r d collaborations in an oligopoly when each firm benefits from the research done by other firms it is connected to in contrast to myopic stability farsighted stability leads to r d networks consisting of two minimally connected components with the largest one comprising three quarters of firms

cooperative and noncooperative r d in an oligopoly with spillovers this paper examines the positive and normative effects of cooperative r d whereby member firms commit themselves to the joint profit maximizing level of r d in a precompetitive stage but remain fierce competitors in the product market vis a vis noncooperative r d socially first best r d and socially second best r d in the presence of sufficiently large r d spillovers neither noncooperative nor cooperative equilibria achieve even second best r d levels in the absence of spillover effects however while the cooperative r d level remains socially insufficient the noncooperative level may overshoot first and second best levels of r d copyright 1992 by american economic association

heterogeneous network games conflicting preferences abstract in many economic situations a player pursues coordination or anti coordination with her neighbors on a network but she also has intrinsic preferences among the available options we here introduce a model which allows to analyze this issue by means of a simple framework in which players endowed with an idiosyncratic identity interact on a social network through strategic complements or substitutes we classify the possible types of nash equilibria under complete information finding two thresholds for switching action that relate to the two player setup of the games this structure of equilibria is considerably reduced when turning to incomplete information in a setup in which players only know the distribution of the number of neighbors of the network for high degrees of heterogeneity in the population the equilibria is such that every player can choose her preferred action whereas if one of the identities is in the minority frustration ensues

the effects of demographic change on the distribution of wages 1967 1990 a multiple skills model was used to examine the impact of changes in labor force composition on the wage distribution of workers by age sex education and race in the us from 1967 through 1990 the model provided for a higher level of specification than previous studies of wage distribution changes in previous investigations workers were grouped into arbitrary and a priori categories and workers in each category were assumed to be perfectly interchangeable in contrast the multiple skills model assumed that each worker had multiple skills that each skill had a productive value and that each skill was an imperfect substitute for other skills the model further assumed that changes in labor force composition would alter the distribution of skills in the labor force which in turn would produce changes in relative wages analysis revealed that wages of young college educated white and nonwhite males relative to the wages of older college educated white and nonwhite males declined since 1967 and were expected to decline throughout the 1980s in contrast the wages of young high school educated white and nonwhite males relative to the wages of older high school educated white and nonwhite males did not decline since 1967 and were not expected to decline during the 1980s the wages of white females of all ages and of all educational levels relative to the wages of males of all ages and of all educational levels declined throughout the period and were expected to decline in the future nonwhite workers made greater gains in wages since 1967 than white males and this trend was expected to continue through the 1980s however the wages of nonwhite males remained absolutely lower than those of white males by 1985 the wages of nonwhite females were expected to surpass those of white females these findings were similar to those observed in other studies except that other studies failed to detect the differential impact on the wages of high school and college educated males

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

endogenous formation of research coalitions with spillovers abstract we examine the endogenous formation of research coalitions with high spillovers among symmetric firms members of a research coalition set their r and d investments in order to maximize the aggregate profits of members of their coalition the exclusive membership rule supports a more concentrated coalition structure and thus leads to higher industry r and d investments for high spillovers than the open membership rule does however due to free riding problems the grand research coalition which is the socially efficient outcome is rarely an equilibrium outcome under either rule our results suggest that government subsidies to research consortia for basic research with high spillovers can improve social welfare by encouraging wider participation to a research consortium that is by alleviating free rider problems in coalition formation from a more theoretical viewpoint our results on stable coalition structures are applicable to a wide variety of economic coalitions with positive externalities

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

choosing organizational modes of strategic technology partnering international and sectoral differences this paper focuses on international strategic technology partnerships and the choice that companies have in terms of the organizational mode either through complex inter organizational modes involving equity sharing or contractual non equity alliances the empirical results show that the choice of particular mode of cooperation varies with the technological characteristics of sectors of industry joint ventures are disproportionately represented in relatively mature industries contractual alliances dominate strategic technology partnering in so called high tech industries

from exogenous to endogenous economic networks internet applications economic agents behaviour is affected by their position in a network either exogenous or endogenous in which they interact with a sub set of neighbours only the network s links which may be generated by vertical and or horizontal relations or by more complex morphologies may explain the transition between dynamic equilibria and the instability of economic aggregates moreover networks shape strategic interaction among agents by determining their strategies the problem of access and interconnection particularly relevant in the internet is perhaps the best example a two way feedback between strategies and network structures arises instead when links are endogenous those features are clearly shown in the mechanism underlying the formation of peering links an dr d networks

coalitional stochastic stability in games networks and markets abstract this paper examines a dynamic process of unilateral and joint deviations of agents and the resulting stochastic evolution of social conventions our model unifies stochastic stability analysis in static settings including normal form games network formation games and simple exchange economies as stochastic stability analysis in a class of interactions in which agents unilaterally and jointly choose their strategies we embed a static setting in a dynamic process over time agents revise their strategies based on the improvements that the new strategy profile offers them in addition to the optimization process there are persistent random shocks on agents utility that potentially lead to switching to suboptimal strategies under a logit specification of choice probabilities we characterize the set of states that will be observed in the long run as noise vanishes we apply these results to examples of certain potential games

environmental economics an evolutionary critique and a plea for pluralism abstract environmental economics is a contradiction in terms the contradiction is intuitive to the puzzled lay person inquiring about the nature of our subdiscipline it is explicit to those who think of environmental systems in terms of complex evolving interconnectedness and identify the economic model with the atomistic and mechanistic assumptions of classical mechanics within the subdiscipline we try to resolve the contradiction by internalizing externalities by matching market feedbacks with environmental relations while acknowledging that insights can be drawn from the market view of environmental problems i argue in this essay that 1 the contradiction is nerver resolved 2 multiple incongruous perspectives are all we have for understanding the interface between economic and environmental systems and 3 environmental economics will thrive with a return to philosophical pluralism to the open acceptance of the contradiction

cross licensing and competition we study bilateral cross licensing agreements between n 2 firms that engage in competition after the licensing phase it is shown that the most collusive cross licensing royalty i e the one that allows the industry to achieve the monopoly profit is sustainable as the outcome of bilaterally efficient agreements in a symmetric setting if the terms of the cross licensing agreements are not observable to third parties the monopoly royalty is the unique symmetric bilaterally efficient royalty however when the terms of the agreements are public the most competitive royalty i e zero can also be bilaterally efficient policy implications regarding the antitrust treatment of cross licensing agreements are derived from these results

network economics and the environment insights and perspectives local interactions and network structures appear to be a prominent feature of many environmental problems this paper discusses a wide range of issues and potential areas of application including the role of relational networks in the pattern of adoption of green technologies common pool resource problems characterized by a multiplicity of sources the role of social networks in multi level environmental governance infrastructural networks in the access to and use of natural resources such as oil and natural gas the use of networks to describe the internal structure of inter country relations in international agreements and the formation of bilateral links in the process of building up an environmental coalition for each of these areas we examine why and how network economics would be an effective conceptual and analytical tool and discuss the main insights that we can foresee

educational attainment and cohort size we argue that the postwar baby boom caused substantial fluctuations in both the economic rewards to education and educational attainment over the last 3 decades if substitutability between young and old workers diminishes with education the present value of lifetime earnings for a boom cohort is depressed more for highly educated workers reducing incentives for educational attainment the opposite is true for pre and postboom cohorts the diminishing substitutability hypothesis explains the declines in both the returns to college and college completion rates in the 1970s and predicts a substantial increase in educational attainment for postboomers

dollars and dreams a reduced middle class alternative explanations we decompose annual earnings into hours of work and hourly earnings and analyze male female differences in earnings inequality using canadian data our results indicate that the larger female inequality in earnings is due to a greater inequality in the

endogenous network formation in patent contests and its role as a barrier to entry in a setting of r d co opetition we study by using an all pay auction approach how collaboration affects strategic decisions during a patent contest and how the latter influences the possible collaboration network structures the firms can hope to form the all pay auction approach allows us to 1 endogenize both network formation and r d intensities and 2 take heterogeneous and private valuations for patents into account we find that different from previous literature the complete network is not always the only pairwise stable network even and especially if the benefits from cooperating are important interestingly the other possible stable networks all have the realistic property that some firms decide not to participate in the contest thus weak cooperation through network formation can serve as a barrier to entry on the market for innovation we further show that there need not be any network that survives a well known refinement of pairwise stability strong stability which imposes networks to be immune to coalitional deviations

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

r d collaboration networks in mixed oligopoly we develop a model of endogenous network formation in order to examine the incentives for r d collaboration in a mixed oligopoly our analysis reveals that the complete network where each firm collaborates with all others is uniquely stable when r d subsidies are not available in addition to the complete network the private partial and the private hub star networks are pareto efficient however the complete network becomes the unique pareto efficient network when r d is subsidized this result is in contrast with earlier contributions in private oligopoly where under strong market rivalry a conflict between stable and efficient networks is likely to occur it also highlights the role of a public firm as policy instrument in aligning individual incentives for collaboration with the objective of efficiency independently of whether r d subsidies are provided by the regulator

cohort crowding how resources affect collegiate attainment abstract analyses of college attainment typically focus on factors affecting enrollment demand including the financial attractiveness of a college education and the availability of financial aid while implicitly assuming that resources available per student on the supply side of the market are elastically supplied the higher education market in the united states is dominated by public and non profit production and colleges and universities receive considerable subsidies from state federal and private sources because consumers pay only a fraction of the cost of production changes in demand are unlikely to be accommodated fully by colleges and universities without commensurate increases in non tuition revenue for this reason public investment in higher education plays a crucial role in determining the degrees produced and the supply of college educated workers to the labor market using data covering the last half of the twentieth century we find strong evidence that large cohorts within states have relatively low undergraduate degree attainment reflecting less than perfect elasticity of supply in the higher education market that large cohorts receive lower public subsidies per student in higher education explains this result indicating that resources have large effects on degree production our results suggest that reduced resources per student following from rising cohort size and lower state expenditures are likely to have significant negative effects on the supply of college educated workers entering the labor market

a framework for analyzing the impact of cohort size on education and labor earning the paper analyzes three models of labor demand solving for the change in wages of a given labor group due to a change in the size of a birth cohort when the production function includes age schooling groups as separate factors an increase in the size of one birth cohort changes the size of several labor market groups also in this case the demand effect of changing factor size is joined by a supply effect of changing schooling proportions ignoring the supply effect may cause us to overestimate the effect of a large birth cohort on wages of young skilled workers

firm heterogeneity and the pattern of r d collaborations we consider an oligopoly setting in which firms form pairwise collaborative links in rd 2 some firms have more innovative capabilities than others these two situations provide clear insights about how firms heterogeneity affects both equilibrium and efficient networks we also show that the most valuable collaborative links do not always appear in equilibrium and a public policy that increases the value of the most valuable links may lead to a loss of social welfare

uncertainty networks and real options abstract two pervasive features of industries experiencing rapid technological progress are uncertainty with regard to the technological feasibility and marketabilility of an innovation and networks the dense web of research alliances and joint ventures linking firms to each other this paper connects the two disparate phenomena using the notion of real options it visualizes firms as nodes and the links connecting them as call options that give each pair of interlinked firms the right but not the obligation to sink additional resources into a project at some future date conditional on favorable technical market information the formation of networks is endogenous as firms establish links with others by appraising their value using option pricing methods our model explains the following why networks are particularly ubiquitous in industries that are subject to high uncertainty why networks often display an interconnected hubs and spokes architecture why small or peripheral spoke firms often sink resources into relatively higher risk higher return investment projects and those too with only large or hub firms and why so many research alliances are continuously formed and dissolved our paper also outlines the conditions under which ex ante symmetric firms end up ex post forming complex asymmetric networks

structural holes in social networks we consider a setting where every pair of players that undertake a transaction e g exchange goods or information creates a unit surplus a transaction can take place only if the players involved have a connection if the connection is direct the two players split the surplus equally while if it is indirect then intermediate players also get an equal share of the surplus thus individuals form links with others to create surplus to gain intermediation rents and to circumvent others who are trying to become intermediary our analysis clarifies the interplay between these forces in the process of strategic network formation first we show that in the absence of capacity constraints on links it leads to the emergence of a star network where a single agent acts as an intermediary for all transactions and enjoys significantly higher payoffs second we study the implications of capacity constraints in the ability of agents to form links in this case distances between players must be long which induces players who are far off to connect in order to avoid paying large intermediation rents a cycle network then emerges payoffs being equal across all players

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

farsighted network formation this paper studies a model of dynamic network formation when individuals are farsighted players evaluate the desirability of a current move in terms of its consequences on the entire discounted stream of payoffs we define a concept of equilibrium which takes into account farsighted behavior of agents and allows for limited cooperation amongst agents we show that an equilibrium process of network formation exists we also show that there are valuation structures in which no equilibrium strategy profile can sustain efficient networks we then provide sufficient conditions under which the equilibrium process will yield efficient outcomes

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

the efficiency and stability of r d networks we investigate the efficiency and stability of r d networks in a model with network dependent indirect spillovers we show that the efficient network structure critically depends on the marginal cost of r d collaborations when the marginal cost is low the complete graph is efficient while high marginal costs imply that the efficient network is asymmetric and has a nested structure regarding the stability of network structures we show the existence of both symmetric and asymmetric equilibria the efficient network is stable for small industry size and small cost in contrast for large industry size there is a wide region of cost in which the efficient network is not stable this implies a divergence between efficiency and stability in large industries

the samuelson condition and the lindahl scheme in networks abstract we study optimal provision of public goods in the network showing that the samuelson condition and the lindahl scheme can both be substantially extended to characterize the expenditure on such public goods couched in terms of the structure of the network the extended samuelson condition and lindahl scheme formulate precisely how the local publicness of a local public good fundamentally determines its optimal provision and the personalized price that the lindahl tax payer faces independence of the optimal allocation from the distribution of resources at interior samuelsonian solutions in the network generally fails to hold even for the bergstrom cornes preferences

biases in technical efficiency scores caused by intra input aggregation mathematical analysis and a dea application using simulated data in data envelopment analysis dea applications involving multiple inputs and outputs inputs are aggregated into the total amounts of each type of input for example if input types labour and capital are used to produce multiple outputs the total amount of labour used to produce all outputs is treated as one aggregated input and the total amount of capital as another resources are not disaggregated into input variables measuring the amount of labour used to produce the first output the amount of labour used to produce the second output the amount of labour used to produce the third output and so on for both labour and capital it is shown that such intra input aggregation causes downward bias in reported technical efficiency scores with variations in bias unrelated to true technical efficiency therefore with few exceptions any technical efficiency comparisons among dmus are invalid the presence of intra input aggregation bias is demonstrated mathematically simulation is used to exhibit it

the substitutability of occupational groups using firm level data abstract labor demand elasticity estimates are presented for a model in which labor groups are defined by occupation while most studies construct labor groups according to non productive characteristics such as race or gender the results corroborate much of the existing research

networks of knowledge among unionized firms we develop a model of strategic networks in order to analyze how trade unions will affect the stability of r d networks through which knowledge is transmitted in an oligopolistic industry whenever firms settle wages the partially connected network is likely to emerge in the long run if and only if knowledge spillovers are large enough however when unions settle wages the complete network is the unique stable network in other words the stronger the union bargaining power is the more symmetric stable r d networks will be in terms of network efficiency the partially connected network when firms settle wages does not pareto dominate the complete network when unions settle wages and vice versa

public policy towards r d in oligopolistic industries the importance of determining optimal policy towards r d cannot be exaggerated given the worldwide interest in fostering r d and given the significant differences between european and u s policies towards interfirm cooperation on r d moreover the problem is an inherently difficult one because of the complex nature of the r d process since r d is a component of fixed costs industries where it is important tend to be concentrated hence r d policy must go hand in hand with competition policy at the same time r d is like any form of investment in that it precedes the production stage hence issues of time consistency and strategic commitment inevitably arise in considering the choice of r d policy finally r d by one firm typically leads to spillovers wbich benefit other firms so that r d exhibits many of the character department of economics university college dublin belfield dublin 4 ireiatid for helpful discussions and comments we are grateful to two anonymous referees to pedro bartos steve martin massimo motta and damien neven and to participants at seminars in birmingham st andrew s and warwick at a cepr workshop on r d spillovers in lausanne at erwit 94 in caslel gandolfo eea 95 in prague the 1996 conference on industrial economics at universidad carlos iii de madrid and a meeting of the dublin economics workshop this paper was produced as part of the international economic performance programme of the centre for economic performance london school of economics supported by the u k esrc an earlier version was circulated as cepr discussion paper no 1243 see alexis jacquemin 1988 and stephen martin 1996 istics of a public good albeit one that is mostly privately produced tbe degree to which such spillovers occur and can be internalized is another crucial influence on the desirable pattem of intervention