policy relevant treatment effects accounting for individual level heterogeneity in the response to treatment is a major development in the econometric literature on program evaluation a substantial body of empirical evidence demonstrates that econometric models fit on individual level data manifest heterogeneity in treatment effects that is present even after conditioning on observables an important distinction is the one between evaluation models where participation in the program being evaluated is based at least in part on unobserved idiosyncratic responses to treatment and models where participation is not based on unobserved idiosyncratic responses this is the distinction between selection on unobservables and selection on observables the validity of entire classes of evaluation estimators hinges on whether or not they allow agents to act on unobserved idiosyncratic responses in a wide variety of applications the available evidence suggests that not only are ex post postenrollment responses heterogeneous but that ex ante decisions to participate in programs are based in part on these heterogeneous responses heckman and vytlacil 2000b 2001

expanding demand through price advertisement abstract retail stores frequently advertise prices when consumer search is costly advertising low prices expands the number of consumers who visit and buy we show that this demand enhancement may offset a retailer s loss in margins from the low price making advertisement desirable we further show that a multi product monopolist may choose to advertise low prices only for select products even when advertised and non advertised products are substitutes for duopolist retailers at a common location an equilibrium exists in which for some range of advertising costs one store advertises and the other free rides on its competitor

the strategic implications of sunk costs a behavioral perspective abstract this paper examines some of the strategic implications of the sunk cost phenomenon in sequential allocation decisions drawing from psychology and behavioral decision theory we first present a taxonomy of possible causes for the sunk cost effect the tendency of many managers to throw good money after bad we then present the analysis of some implications of this behavior in strategic situations a two period strategic game is developed and analyzed to derive optimal allocations as a function of one player s sunk cost behavior we establish when this behavior can be used as a successful precommitment strategy by the sunk cost player and when it is exploitable by an opponent welfare implications are also explored the sunk cost effect constitutes a form of strategic preference manipulation in which a credible preference change can be induced to provide a strategic advantage to one of the players

micro data heterogeneity and the evaluation of public policy nobel lecture this paper summarizes the contributions of microeconometrics to economic knowledge four main themes are developed 1 microeconometricians developed new tools to respond to econometric problems raised by the analysis of the new sources of micro data produced after the second world war 2 microeconometrics improved on aggregate time series methods by building models that linked economic models for individuals to data on individual behavior 3 an important empirical regularity detected by the field is the diversity and heterogeneity of behavior this heterogeneity has profound consequences for economic theory and for econometric practice 4 microeconometrics has contributed substantially to the scientific evaluation of public policy

optimal warranties reliabilities and prices for durable goods in an oligopoly this paper addresses the problem of durable goods manufacturers in an oligopoly seeking optimal values for three decision variables product warranty reliability and price each firm seeks a warranty reliability price combination that maximizes expected profit subject to quite general constraints on the firm s decision variables warranty serves as a signal of product reliability which is not observable by consumers we present a game theoretic model of warranty reliability price competition in such a market and examine nash equilibria for this game we show that under fairly general assumptions each firm can optimally set its warranty and reliability independently of price and competitors actions in addition we show that optimal warranties and reliabilities are complementary and we explore the impact of different market factors on the optimal warranty and reliability finally we show that optimal warranties are longer and products more reliable when consumers are risk averse

optimal task assignments with loss averse agents abstract this paper studies optimal task assignments in a setting where agents are expectation based loss averse according to koszegi and rabin 2006 2007 and are compensated according to an aggregated performance measure in which tasks are technologically independent we show that the optimal task assignment is determined by a trade off between paying lower compensation costs and restricting the set of implementable effort profiles under multitasking we show that loss aversion combined with how much the marginal cost of effort in one task increases with the effort chosen in other tasks determines when multitasking saves on compensation costs but results in an implementation problem

comparative statics by adaptive dynamics and the correspondence principle the intuition behind comparative statics results is usually dynamic in nature the economic explanation for why differences in endogenous variables result from variations in exogenous variables often takes the form of some sequential adjustment process for example consider the account by milgrom qian and roberts 1991 of technological and organizational changes in modern manufacturing the falling costs of high speed data communication data processing and flexible multitask equipment lead to increases in the directly affected activities which through a web of complementarities then lead to increases in a set of related activities as well despite the prevalence of dynamic economic explanations the formal analysis is static in games of strategic complementarities gsc topkis 1979 vives 1990 parameterized by a variable that is complementary to the choice variables the existing results on monotone comparative statics of equilibria are summarized by a theorem of milgrom and roberts 1990 mr hereafter the largest and smallest equilibria in a parameterized gsc

does foreign aid increase private investment evidence from panel cointegration this article uses panel cointegration and causality techniques to examine the long run relationship between foreign aid and private investment our main result is that aid has a statistically significant negative effect on private investment this result is robust to outliers different measures and forms of aid sample selection and the sample period in addition we find that long run causality runs in both directions suggesting that an increase in aid reduces private investment and that in turn higher private investment leads to lower aid inflows

installed base and compatibility innovation product preannouncements and predation a good is often more valuable to any user the more others use compatible goods the authors show that this effect may inhibit innovation if an installed base exists and transition to a new standard must be gradual early adopters bear a disproportionate share of transient incompatibility costs this can produce excess inertia the installed base however is stranded if the new standard is adopted this may create excess momentum these dynamic effects have strategic implications temporary price cutting can permanently prevent entry and product preannouncements can be critical in innovation these strategic actions have ambiguous welfare effects

sharing default information as a borrower discipline device abstract creditors often share information about their customers credit records besides helping them to spot bad risks this acts as a disciplinary device if creditors are known to inform one another of defaults borrowers must consider that default on one lender would disrupt their credit rating with all the other lenders this increases their incentive to perform however sharing more detailed information can reduce this disciplinary effect borrowers incentives to perform may be greater when lenders only disclose past defaults than when they share all their information in some instances by fine tuning the type and accuracy of the information shared lenders can raise borrowers incentives to their first best level

testing models with multiple equilibria by quantile methods this paper proposes a method for testing complementarities between explanatory and dependent variables in a large class of economic models the proposed test is based on the monotone comparative statics mcs property of equilibria our main result is that mcs produces testable implications on the small and large quantiles of the dependent variable despite the presence of multiple equilibria the key features of our approach are that i we work with a nonparametric structural model of a continuous dependent variable in which the unobservable is allowed to be correlated with the explanatory variable in a reasonably general way ii we do not require the structural function to be known or estimable iii we remain fairly agnostic on how an equilibrium is selected we illustrate the usefulness of our result for policy evaluation within berry levinsohn and pakes s 1999 model

learning dynamics for mechanism design an experimental comparison of public goods mechanisms in a repeated interaction public goods economy incomplete information and dynamic behavior may affect the realized outcomes of mechanisms known to be efficient in a complete information oneshot game an experimental test of five public goods mechanisms indicates that subjects with private information appear to best respond to recent observations this provides predictions about which mechanisms will generate convergence to their efficient equilibrium allocations these predictions match the experimental result that globally stable efficient mechanisms realize the highest efficiency in practice the simplicity of the suggested best response model makes it useful in predicting stability of mechanisms not yet tested

learning to deal with repeated shocks under strategic complementarity an experiment experimental evidence shows that the rational expectations hypothesis fails to characterize the path to equilibrium after an exogenous shock when actions are strategic complements under identical shocks however repetition allows adaptive learning so that inertia in adjustment should fade away with experience if this finding proves to be robust inertia in adjustment may be irrelevant among experienced agents the conjecture in the literature is that inertia would still persist perhaps indefinitely in the presence of real world complications such as nonidentical shocks herein we empirically test the conjecture that the inertia in adjustment is more persistent if the shocks are nonidentical for both identical and nonidentical shocks we find persistent inertia and similar patterns of adjustment that can be explained by backward looking expectation rules a reformulation of naive expectations with similarity based learning approach is found to have a higher predictive power than rational and trend following rules

on using linear regressions in welfare economics this article consists of two parts the first part shows that the ordinary least squares regression coefficient is a weighted average of slopes between adjacent sample points when applied to a linear regression with income as the independent variable the regression coefficient depends heavily on the slopes of high income groups the weight of the highest income decile may well exceed that of the other nine deciles this may be undesirable especially if the regression is used for welfare analysis because the marginal propensities to consume attributed to the commodities are determined by the high income groups the second part of the article proposes alternative estimators the extended gini estimators that enable investigators to control the weighting scheme and to incorporate their social views into the weighting scheme of the estimators

aggregate comparative statics abstract in aggregative games each player s payoff depends on her own actions and an aggregate of the actions of all the players many common games in industrial organization political economy public economics and macroeconomics can be cast as aggregative games this paper provides a general and tractable framework for comparative static results in aggregative games we focus on two classes of games 1 aggregative games with strategic substitutes and 2 nice aggregative games where payoff functions are continuous and concave in own strategies we provide simple sufficient conditions under which positive shocks to individual players increase their own actions and have monotone effects on the aggregate the results are illustrated with applications to public good provision contests cournot competition and technology choices in oligopoly

hysteresis in east asian unemployment high performing asian economies are quite distinctive with efficient flexible and responsive labour markets comparing the persistence of unemployment in east asian economies to that in western countries is difficult due to the data s short time spans and possible structural breaks this article employs advanced unit root tests to deal with these problems and fails to reject hysteresis in the unemployment rates of the high performing asian countries even after taking into account structural change an alternative explanation of different productivity growth for the hysteresis phenomenon of the asian countries is proposed herein

set identification in models with multiple equilibria we propose a computationally feasible way of deriving the identified features of models with multiple equilibria in pure or mixed strategies it is shown that in the case of shapley regular normal form games the identified set is characterized by the inclusion of the true data distribution within the core of a choquet capacity which is interpreted as the generalized likelihood of the model in turn this inclusion is characterized by a finite set of inequalities and efficient and easily implementable combinatorial methods are described to check them in all normal form games the identified set is characterized in terms of the value of a submodular or convex optimization program efficient algorithms are then given and compared to check inclusion of a parameter in this identified set the latter are illustrated with family bargaining games and oligopoly entry games copyright 2011 oxford university press

on modeling the advertising operations interface under asymmetric competition abstract using a market share attraction structure of advertising competition and following a supermodular game approach this article demonstrates for an asymmetric oligopoly the directional impact of changes in model parameters on the marketing controlled variables of all rivals advertising budgets and the operations controlled variables of all rivals ordered quantities importantly the various changes are examined analytically empirically and numerically in both non dominated and dominated asymmetric oligopolies in this regard the results indicate that firms in a dominated oligopoly one firm of market share larger than or equal to 50 behave differently compared to firms in a non dominated oligopoly each firm of market share less than 50 in response to changes in model parameters furthermore changes in model parameters are investigated in terms of their relative influential impact on a variety of equilibrium measures in this regard the findings indicate that for the analyzed model the marketing parameters exert much more influence on the equilibrium measures than the operations parameters additionally a change in the mode of competition from non cooperation oligopoly to cooperation joint ownership dictates that strong asymmetric firms of favorable marketing and operations parameters continue advertising but at lower levels and weak asymmetric firms of less favorable parameters cease advertising altogether

dynamic monotonicity and comparative statics for real options abstract we analyze the relationship between complementarities and monotonicity in dynamic programs while complementarities supermodularity and nondecreasing differences are sufficient for monotonic statics in stochastic dynamic programs they are only robustly necessary in a limited way under heavy discounting monotonicity of the decision rule doesnotin general imply monotonicity of the optimal path in fact optimal paths in such models may exhibit extremely complex behavior for convex adjustment costs many real option models have monotone decision rules while for fixed costs they typically do not we also strengthen a well known characterization of complementarities due to milgrom and shannon 19 journal of economic literatureclassification numbers c61 d92 e22

correlated equilibrium as an expression of bayesian rationality if it is common knowledge that the players in a game are bayesian utility maximizers who treat uncertainty about other players actions like any other uncertainty then the outcome is necessarily a correlated equilibrium random strategies appear as an expression of each player s uncertainty about what the others will do not as the result of willful randomization use is made of the common prior assumption according to which differences in probability assessments by different individuals are due to the different information that they have where information may be interpreted broadly to include experience upbringing and genetic makeup copyright 1987 by the econometric society

strategic complements and substitutes and potential games abstract we show that games of strategic complements or substitutes with aggregation are pseudo potential games the upshot is that they possess nash equilibria in pure strategies ne even if the strategy sets are not convex and that various dynamic processes converge to ne in particular ne exist in cournot oligopoly with indivisibilities in production our notion of aggregation is quite general and enables us to take a unified view of several disparate models

bertrand supertraps we study oligopoly price competition between multiproduct firms firms whose products interact in the profit function specifically we focus on the impact of intrafirm product interactions on the level of equilibrium profits this impact may be decomposed in two different ways a a direct effect keeping the competitors actions fixed plus a strategic effect i e through the competitors actions or alternatively b a competitive advantage effect change in firmi only plus an imitation effect change in all other firms we derive conditions such that a the strategic effect more than outweighs the direct effect and conditions such that b the imitation effect more than outweighs the competitive advantage effect bertrand supertraps for example an increase in the degree of economies of scope would increase profits if prices were fixed or if the change were limited to firmi s cost function however if all firms increase the degree of economies of scope then all firms receive lower profits a variety of other applications is considered including learning curves core competencies demand synergies systems competition compatibility bundling network effects switching costs durable goods long term contracts

estimating the economic return to educational levels using data on twins this paper relaxes some restrictions of previous twin based estimates of the effects of education on earnings first it estimates the earnings premiums associated with different educational levels second it estimates a piecewise linear relationship between the natural logarithm of annual earnings and years of schooling third the measurement error corrections are based on a less restrictive non classical measurement error model the estimation strategy implies that ability bias can be investigated separately in different parts of the educational distribution the linear relationship between the logarithm of annual earnings and years of schooling is rejected furthermore the results in the sample of identical mz twins indicated both that the ability bias could be of different signs and of different magnitudes in different parts of the educational distribution the twin based estimates in the sample of fraternal dz twins did not display any marked differences as compared to the cross sectional estimates finally the results indicated that the error corrected twin based estimates of the average return to years of schooling that rely on a classical measurement error model are upwards biased by approximately 30 copyright 2004 john wiley sons ltd

rationalizable strategic behavior the notion of equilibrium proposed by nash 19 has come to play a dominant role in economic applications of noncooperative games while analyses of nash equilibria have unquestionably contributed to our understanding of economic behavior it would be unreasonably optimistic to maintain that nash solved the problem of noncooperative strategic choice there is a small literature beginning with ellsberg 6 and a much larger oral tradition which argues that nash behavior is neither a necessary consequence of rationality nor a reasonable empirical proposition in this paper i take the view that although there may be various reasons why an agent might select a nash strategy the notion of an equilibrium has little intrinsic appeal within a strategic context when an agent reaches a decision in ignorance of the strategies adopted by other players rationality consists of making a choice which is justifiable by an internally consistent system of beliefs rather than one which is optimal post hoc this point of view is not original indeed most serious justifications of the nash hypothesis embrace such an approach arguing that agents will expect the game to yield a nash outcome and consequently will choose their equilibrium strategies nevertheless when we think in terms of maximizing utility subject to expectations rather than realizations it becomes clear that the nash hypothesis far from being a consequence of rationality arises from certain restrictions on agents expectations which may or may not be plausible depending upon the game being played we are then quite naturally led to ask are there any restrictions of individuals expectations and hence choices which are required by rationality alone rather than by subjective plausibility this paper is concerned with defining justifying characterizing and refining a criterion for rational strategic choice which i label rationalizability

an experimental study of uncertainty in coordination games global games and poisson games have been proposed to address equilibrium indeterminacy in common knowledge coordination games where fundamentals are commonly known by all players global games assume that agents face idiosyncratic uncertainty about economic fundamentals whereas poisson games model the number of actual players as a poisson random variable to capture population uncertainty in large games the present study investigates in a controlled setup using as controls common knowledge coordination games whether idiosyncratic uncertainty about economic fundamentals or uncertainty about the number of actual players may influence subjects behavior our findings suggest that uncertainty about the number of actual players has a more significant impact on subjects behavior than idiosyncratic uncertainty about economic fundamentals furthermore subjects behavior under poisson population size uncertainty is consistent with the theoretical prediction of poisson coordination games

noncooperative versus cooperative r d with endogenous spillover rates this paper deals with a general version of a two stage model of r d and product market competition we provide a thorough generalization of previous results on the comparative performance of noncooperative and cooperative r d dispensing in particular with ex post firm symmetry and linear demand assumptions we also characterize the structure of profit maximizing r d cartels where firms competing in a product market jointly decide r d expenditure as well as internal spillover levels we establish the firms would essentially always prefer extremal spillovers and within the context of a standard specification derive conditions for the optimality of minimal spillover

strong comparative statics of equilibria some results in the monotone comparative statics literature tell us that if a parameter increases some old equilibria are smaller than some new equilibria we give a sufficient condition such that at a new parameter value every old equilibrium is smaller than every new equilibrium we also adapt a standard algorithm to compute a minimal such newer parameter value and apply this algorithm to a game of network externalities our results are independent of a theory of equilibrium selection and are valid for games of strategic complementarities

learning in games with strategic complementarities revisited fictitious play is a classical learning process for games and games with strategic complementarities are an important class including many economic applications knowledge about convergence properties of fictitious play in this class of games is scarce however beyond games with a unique equilibrium global convergence has only been claimed for games with diminishing returns v krishna learning in games with strategic complementarities hbs working paper 92 073 harvard university 1992 this result remained unpublished and it relies on a specific tie breaking rule here we prove an extension of it by showing that the ordinal version of strategic complementarities suffices the proof does not rely on tie breaking rules and provides some intuition for the result

estimating the value of an in kind transfer the case of food stamps the value of one in kind transfer food stamps is estimated by evaluating the experience of an actual conversion from stamps to cash in puerto rico in 1982 the evidence indicates that the cashout of the stamps had no detectable influence on food expenditures the explanation partly lies in the distribution of expenditures for the stamps were inframarginal for most recipients however some evidence indicates that trafficking in stamps was widespread as well including indirect evidence from estimation of the piecewise linear constraint model copyright 1989 by the econometric society

a global game with strategic substitutes and complements abstract we study a global game in which actions are strategic complements over some region and strategic substitutes over another region an agent s payoff depends on a market fundamental and the actions of other agents if the degree of congestion is sufficiently large agents strategies are non monotonic in their signal about the market fundamental in this case a signal that makes them believe that the market fundamental is more favorable for an action may make them less likely to take the action because of the risk of overcrowding

rationalizable strategic behavior and the problem of perfection this paper explores the fundamental problem of what can be inferred about the outcome of a noncooperative game from the rationality of the players and from the information they possess the answer is summarized in a solution concept called rationalizability strategy profiles that are rationalizable are not always nash equilibria conversely the information in an extensive form game often allows certain unreasonable nash equilibria to be excluded from the set of rationalizable profiles a stronger form of rationalizability is appropriate if players are known to be not merely rational but also cautious what constitutes rational behavior in a noncooperative strategic situation this paper explores the issue in the context of a wide class of finite noncooperative games in extensive form the traditional answer relies heavily upon the idea of nash equilibrium nash 17 the position developed here however is that as a criterion for judging a profile of strategies to be reasonable choices for players in a game the nash equilibrium property is neither necessary nor sufficient some nash equilibria are intuitively unreasonable and not all reasonable strategy profiles are nash equilibria the fact that a nash equilibrium can be intuitively unattractive is well known the equilibrium may be imperfect introduced into the literature by selten 20 the idea of imperfect equilibria has prompted game theorists to search for a narrower definition of equilibrium while this research some of which will be discussed here has been extremely instructive it remains inconclusive theorists often agree about what should happen in particular games but to capture this intuition in a general solution concept has proved to be very difficult if this paper is successful it should make some progress in that direction the other side of the coin has received less scrutiny can all non nash profiles really be excluded on logical grounds i believe not the standard justifications for considering only nash profiles are circular in nature or make gratuitous assumptions about players decision criteria or beliefs the following discussion of these points is extremely brief due to space constraints more detailed arguments may be found in pearce 18

technological progress and optimal supply price abstract this article presents an analysis of the firm s optimal product price decision as a joint process with optimal production planning the production decision is formulated as a dynamic optimization problem over an infinite horizon under conditions of profit maximization and rational expectation given a set of market and technical progress information the problem is solved to obtain the time paths of shadow prices of capital and labor services these shadow prices of factors are combined to construct the time path of the optimal supply price sensitivity analysis are conducted on the optimal supply price to isolate the variational effects of technical progress and labor turnover rate the results are stated as propositions

technology asymmetries group algebra and multiplant cost minimization for a homogeneous good this article studies firm level production activities when the firm controls a plural number of plants through careful construction of cost function technology asymmetries we inquire into the ordinal structure of the production vector for multiplant cost minimizers when schur convexity of a reference pseudo cost technology is the principal functional assumption then ordinal concepts of technical asymmetries map into rank order on the equilibrium production vector under a more generalized characterization of the technical asymmetries a multiplant firm encounters group theory is used to map a cardinal concept of asymmetries into cardinal bounds on the optimum allocation

portfolio selection with qualitative input abstract we formulate a mean variance portfolio selection problem that accommodates qualitative input about expected returns and provide an algorithm that solves the problem this model and algorithm can be used for example when a portfolio manager determines that one industry will benefit more from a regulatory change than another but is unable to quantify the degree of difference qualitative views are expressed in terms of linear inequalities among expected returns our formulation builds on the black litterman model for portfolio selection the algorithm makes use of an adaptation of the hit and run method for markov chain monte carlo simulation we also present computational results that illustrate advantages of our approach over alternative heuristic methods for incorporating qualitative input

technology adoption in the presence of network externalities we analyze technology adoption in industries where network externalities are significant the pattern of adoption depends on whether technologies are sponsored a sponsor is an entity that has property rights to the technology and hence is willing to make investments to promote it key findings include the following 1 compatibility tends to be undersupplied by the market but excessive standardization can occur 2 in the absence of sponsors the technology superior today has a strategic advantage and is likely to dominate the market 3 when one of two rival technologies is sponsored that technology has a strategic advantage and may be adopted even if it is inferior 4 when two competing technologies both are sponsored the technology that will be superior tomorrow has a strategic advantage

real exchange rate behavior and economic performance in ldcs in recent years policy discussions have included increasing references to real exchange rate rer stability and correct exchange rate alignment as crucial conditions to improve economic performance in less developed countries ldcs 1 evidence from latin american asian and african countries is often quoted to support the view that the link between rer behavior and economic performance is strong it is argued that while unstable rers inhibited export growth in some of latin america their stability was fundamental in promoting east asian expansion in many african countries on the other hand persistently misaligned local currencies harmed the development of agriculture reducing domestic food supply 2 but in spite of its importance no empirical work has been attempted either to test the relationship between rer behavior and performance indicators at a broad multicountry level or to investigate the sources of rer variability and misalignment in ldcs the theoretical literature on rer determinants has been recently surveyed by sebastian edwards 3 he distinguishes between equilibrium and disequilibrium rers and between external and domestic rer determinants although domestic policies are often said to account for significant rer variations empirical work has only concentrated on the effect of nominal devaluations4 or speculative crises arising from expansionary monetary policies in a system of fixed ex

equilibrium selection in imperfectly competitive economies with multiple equilibria this paper investigates the selection of an equilibrium in an economy with multiple pareto ranked nash equilibria a history dependent selection criterion is proposed which induces correlated behavior in equilibrium even though agents are playing one shot games and disturbances are not correlated over time the model economy may experience prolonged periods in which a low productivity technology is in use and then as a consequence of a large real disturbance may switch to an alternative equilibrium in which a high productivity technology is utilized thus the model qualitatively matches observations of serially correlated movements in output and employment and generates procyclical productivity though there are no exogenous technology shocks copyright 1994 by royal economic society

aggregate pattern of time dependent adjustment rules ii strategic complementarity and endogenous nonsynchronization abstract this paper provides an explanation for an important institutional feature of staggered time dependent adjustment rules assumed in a number of macroeconomic models it identifies strategic complementarity as the crucial factor leading to nonsynchronized decisions in a game theoretic framework the paper first shows that nonsynchronization is the equilibrium outcome in an infinite horizon game in which strategic complementarity is present whether the players choose predetermined or fixed actions by pursuing the interpretation of a nonsynchronized move dynamic game as a series of games with symmetric stackelberg leadership it is further suggested that the relationship between strategic complementarity and the benefit to the stackelberg follower provides the insight to the game theoretic explanation of nonsynchronization the results of this paper reveal a link between strategic complementarity and nonsynchronization two important macroeconomic features journal of economic literature classification numbers e30 l16

economists models of learning abstract economic theorists have intensively studied learning in games and decisions over the last decade this essay puts some of the work in perspective and offers opinions about what still needs to be learned journal of economic literature classification numbers c73 d83

reputation and turnover we consider a repeated duopoly game where each firm privately chooses its investment in quality and realized quality is a noisy indicator of the firm s investment we focus on turnover equilibria in which a low quality realization is penalized by lowering future demand of the firm that delivered this quality we determine when a turnover equilibrium that gives higher welfare than the static equilibrium exists and how this relates to market fundamentals we also derive comparative statics properties and we characterize a set of investment levels and hence payoffs that turnover equilibria sustain

optimal contracting of separable production technologies abstract we analyze the class of agency problems with a risk neutral principal and a risk averse agent in which hidden actions and hidden information on the agent s efficiency are jointly present technological assumptions such as monotonicity of likelihood are no longer sufficient for the optimal contract to be monotone in the sharing rule we show that these regularity properties obtain for the rather wide class of production technologies that are separable in the agent s inputs together with ordinal properties such as monotone differences and affiliation of inputs separability yields the monotonicity in efficiency of the agent s actions and indirect utility

strategic differentiation and strategic emulation in games with uncertainty when players who choose a common strategy face a common shock while players who choose different strategies face independent or imperfectly correlated shocks equilibrium choices exhibit differentiation respectively emulation when the sign of the cross partial derivative of the firms profit functions with respect to the realizations of the uncertain variables is negative respectively positive i consider a variety of applications including technology choice brand investments and r d races many of which can be characterized as two stage games in such games i demonstrate that differentiation is more likely to occur when the second stage game is a game of strategic substitutes

do panel data permit the rescue of the balassa samuelson hypothesis for latin american countries this paper tests empirically the balassa samuelson bs hypothesis i e rapid economic growth is accompanied by real exchange rate appreciation because of differential productivity growth between tradable and non tradable sectors using annual data for twenty latin american countries the paper applies new panel data unit root tests proposed by im et al discussion paper university of cambridge june 1997 and new panel data cointegration techniques suggested by pedroni oxford bulletin of economics and statistics 1999 and the results are compared with those obtained with conventional time series unit roots and cointegration tests the main finding is that whereas a standard time series approach rejects the balassa samuelson hypothesis for 11 countries out of 20 new panel cointegration techniques permit the rescue of this hypothesis for latin american countries as well as for central american and south american groups of countries considered separately

relative deprivation and economic welfare abstract it is shown that the theory of relative deprivation can be decomposed into two concepts deprivation and its relativity deprivation is interpreted as forgone utility due to lack of commodities thus minimizing deprivation and maximizing utility come to much the same thing the relativity of the concept stems from the existence of reference groups in the society the core of the paper deals with the effect of reference groups on the deprivation felt in the society

a discrete choice model with social interactions with an application to high school teen behavior we develop an empirical discrete choice interaction model with a finite number of agents we characterize its equilibrium properties in particular the correspondence between interaction strength number of agents and the set of equilibria and propose to estimate the model by means of simulation methods in an empirical application we analyze the individual behavior of high school teenagers in almost 500 school classes from 70 schools in our baseline model endogenous social interaction effects are strong for behavior closely related to school truancy somewhat weaker for behavior partly related to school smoking cell phone ownership and moped ownership and absent for behavior far away from school asking parents permission for purchases intra gender interactions are generally much stronger than cross gender interactions in a model with school specific fixed effects social interaction effects are insignificant with the exception of intra gender interactions for truancy copyright c 2007 john wiley sons ltd

the strategy of manipulating conflict two decision makers choose hawkish or dovish actions in a con ict game with incomplete information the decision making can be manipulated by extremists who send publicly observed cheaptalk messages the power of extremists depends on the nature of the underlying con ict game if actions are strategic complements a hawkish extremist provocateur can increase the likelihood of con ict by sending messages which trigger a fear spiral of hawkish actions this reduces the welfare of both decision makers if actions are strategic substitutes a dovish extremist paci st can send messages which cause one decision maker to back down and become more dovish this reduces his welfare but bene ts the other decision maker the hawkish extremist is unable to manipulate the decision makers if actions are strategic substitutes and the paci st is equally powerless if actions are strategic complements

decreasing serial cost sharing under economies of scale we consider the problem of cost sharing in the presence of increasing returns to scale and potential strategic behavior on the part of consumers we show that any smooth and strictly monotonic mechanism for which a nash equilibrium exists for all profiles of convex and monotonic preferences must be dictatorial however we propose a cost sharing mechanism the decreasing serial mechanism for which an interesting domain restriction ensures existence of a noncooperative equilibrium for its cost sharing game a characterization theorem of the mechanism based on the strategic properties of existence uniqueness and efficiency of its noncooperative equilibrium is provided journal of economic literature classification numbers c70 c72 d70 cost allocation is a practical problem that organizations of all kinds face universities allocate computing costs among departments aviation authorities set landing fees for aircraft based on their size regulatory com missions set rates for electricity water and other utilities based on the costs of providing these services the common feature in all of these exam ples is that prices are not determined externally by market forces but are set internally by mutual agreement or administrative decision a simple situation where a cost sharing problem can emerge is when a set of users share a technology that transforms a single input into a single output we study this cost sharing problem when the cost function is increasing and concave examples include the division of costs incurred in setting telephone lines or a water supply system the assessment of fees to pay for a secretary or a gardener s services and so on the situations we have in mind are those of cooperative production or natural nonregulated monopolies for either of these situations there is no obvious answer to the question of how to divide the cost of producing the total output among the users

efficiency in partnership structures abstract consider an economy where agents differ in production skills and abilities and are free to form production coalitions or partnerships with each other farrell and scotchmer 1988 showed that if partners are restricted to equal output sharing in equilibrium the partnerships are inefficiently small we elaborate on another possible source of inefficiency which is due to composition rather than size under the equal sharing constraint high ability agents form partnerships with agents of similar ability levels yet mixing of ability levels may be socially efficient we further investigate whether relaxing the equal sharing constraint corrects the inefficiency of equilibrium

selfish drug allocation for containing an international influenza pandemic at the onset recent epidemiologic studies have suggested that the prophylactic use of antiviral drugs could slow down the spread of an influenza epidemic because drug stockpiles are presently scattered in different countries the outbreak of an epidemic gives rise to a game in which each country must make decisions about how best to allocate its own stockpile in order to protect its population we develop a two period multivariate reed frost model to represent the spread of the epidemic within and across countries at its onset we consider the first two periods only to mimic the exponential growth of an epidemic in its early stage while keeping the model tractable preliminary numerical studies suggest that insights from the two period model hold in general when considering the entire time horizon our model captures three critical sources of uncertainty the number of initial infections the spread of the disease and drug efficacy we show that for small probabilities of between country infections the underlying game is supermodular nash equilibrium exists and there is a unique one that is pareto optimal among all existing equilibria further we identify sufficient conditions under which the optimal solution of a central planner such as the world health organization constitutes a pareto improvement over the decentralized equilibrium suggesting that countries should agree on an allocation scheme that would benefit everyone by contrast when the central planner s solution does not constitute a pareto improvement minimizing the total number of infected persons globally requires some countries to sacrifice part of their own population which raises intriguing ethical issues

network effects market structure and industry performance abstract this paper analyzes oligopolistic markets with network externalities exploiting a minimal complementarity structure on the model primitives that allows for pure network goods we prove existence of non trivial fulfilled expectations equilibrium we formalize the concept of industry viability investigate its determinants and show that it improves with more firms in the market and or by technological progress these results enlighten some well known conclusions from case studies in the management strategy literature we also characterize the effects of market structure on industry performance which depart substantially from ordinary markets the approach relies on lattice theoretic methods supplemented with basic insights from nonsmooth analysis

the effect of education on crime evidence from prison inmates arrests and self reports we estimate the effect of high school graduation on participation in criminal activity accounting for endogeneity of schooling we begin by analyzing the effect of high school graduation on incarceration using census data instrumental variable estimates using changes in state compulsory attendance laws as an instrument for high school graduation uncover a significant reduction in incarceration for both blacks and whites when estimating the impact of high school graduation only ols and iv estimators estimate different weighted sums of the impact of each schooling progression on the probability of incarceration we clarify the relationship between ols and iv estimates and show that the weights placed on the impact of each schooling progression can explain differences in the estimates overall the estimates suggest that completing high school reduces the probability of incarceration by about 76 percentage points for whites and 3 4 percentage points for blacks we corroborate these findings using fbi data on arrests that distinguish among different types of crimes the biggest impacts of graduation are associated with murder assault and motor vehicle theft we also examine the effect of drop out on self reported crime in the nlsy and find that our estimates for imprisonment and arrest are caused by changes in criminal behavior and not educational differences in the probability of arrest or incarceration conditional on crime we estimate that the externality of education is about 14 26 of the private return to schooling suggesting that a significant part of the social return to education comes in the form of externalities from crime reduction

warrant exercise dividends and reinvestment policy in this paper we examine sequential exercise strategies by warrantholders and the gain from hoarding warrants we analyze several obstacles to acquiring large blocks in order to exploit sequential strategies first we identify several reinvestment policies for which sequential exercise is not advantageous thereby eliminating the gain from hoarding however sequential exercise strategies may be advantageous for monopoly or oligopoly warrantholders even absent dividends because using exercise proceeds to repurchase stock or to expand the firm s scale increases the riskiness of an equity share second oligopoly warrantholders can receive a smaller warrant value than perfectly competitive warrantholders suggesting a potential cost to unsuccessful hoarding

lechatelier samuelson principle in games and pass through of shocks abstract the lechatelier samuelson principle states that as a reaction to a shock an agent s short run adjustment of an affected action is smaller than its long run adjustment when the agent can also adjust other related actions we extend the principle to strategic environments where the long run adjustment also accounts for other players adjusting their strategies we show that the principle holds for supermodular games strategic complements satisfying monotone comparative statics and provide sufficient conditions for the principle to hold in games of strategic substitutes heterogeneity we discuss the principle s implications for cost pass through of multiproduct firms

endogenous timing in the presence of non monotonicities the aim of this paper is to generalize the endogenous timing game proposed by hamilton and slutsky games and economic behavior 1990 2 pp 29 46 by allowing the payoff or the marginal payoff of a player to become non monotonic with respect to the strategy of the opponent we propose a taxonomy of the subgame perfect nash equilibria based on the characteristics of the payoff functions proposed by eaton canadian journal of economics 2004 37 pp 805 29 we determine under which conditions of the initial payoff functions commitment has a social value and when the simultaneous move nash equilibrium is commitment robust and discuss its pareto efficiency

supermodularity and complementarity in economics an elementary survey the literature on supermodular optimization and games is surveyed from the perspective of potential users in economics this methodology provides a new approach for comparative statics based only on critical assumptions and allows a general analysis of games with strategic complementarities the results are presented in a simplified yet rigourous manner without reference to lattice theory for the special case of one dimensional parameter and actions sets with the emphasis being on wide accessibility detailed applications are presented for well known models of consumer behavior monopoly pass through bertrand and cournot competition strategic r d search and matching wherever appropriate useful tricks for applications and comparative comments are inserted

asymmetric information information externalities and efficiency the case of oil exploration in this article we examine the efect of private information and information externalities on the ex post eficiency of investment in oil exploration we show that too much drilling tends to occur ifjirms believe that the area is likely to contain a sizeable pool of oil and too little drilling occurs if the opposite is true bargaining with well defined property rights to the information externality can eliminate underinvestment but overinvestment remains a problem because firms have an incentive not to disclose their private information

optimism and pessimism in games this paper considers the impact of ambiguity in strategic situations it extends the earlier literature by allowing for optimistic responses to ambiguity ambiguity is modelled by ceu preferences we propose a new solution concept for players who may express ambiguitypreference then we study comparative statics of changes in ambiguity attitude in games with strategic complements this gives a precise statement of the impact of ambiguity on economic behaviour

is there a unit root in the inflation rate evidence from sequential break and panel data models summary using sequential trend break and panel data models we investigate the unit root hypothesis for the inflation rates of thirteen oecd countries with individual country tests we find evidence of stationarity in only four of the thirteen countries the results are more striking with the panel data model we can strongly reject the unit root hypothesis both for a panel of all thirteen countries and for a number of smaller panels consisting of as few as three countries the non rejection of the unit root hypothesis for inflation is very fragile to even a small amount of cross section variation 1997 john wiley sons ltd

on the effects of entry in cournot markets in the framework of symmetric cournot oligopoly this paper provides two minimal sets of assumptions on the demand and cost functions that imply respectively that as the number of firms increases the minimal and maximal equilibria lead to i decreasing industry price and increasing or decreasing per firm output and ii increasing industry price and decreasing per firm output in both cases per firm profits are decreasing the analysis relies crucially on lattice theoretic methods and yields general unambiguous and easily interpretable conclusions of a global nature as a byproduct of independent interest new insight into existence of cournot equilibrium is developed

adoption externalities as public goods abstract a public good problem arises naturally in situations characterized by positive externalities or negative externalities for positive externalities agents furnish a public good by taking an action similarly for negative externalities agents furnish a public good by not taking an action we examine these externalities in a binary choice problem i e adoption externalities in each case there is a potential role for government intervention even when equilibrium transfers are not allowed since one equilibrium pareto dominates all others we analyze the positive and normative features of equilibria in these models and we explore the possibility of useful government intervention

does competition solve the hold up problem in an environment in which heterogeneous buyers and sellers undertake ex ante investments the presence of market competition for matches provides incentives for investment but may leave inefficiencies namely hold up and coordination problems this paper shows using an explicitly non cooperative model that when matching is assortative and investments precede market competition buyers investments are constrained efficient while sellers marginally underinvest with respect to what would be constrained efficient however the overall extent of this inefficiency may be large multiple equilibria may arise one equilibrium is characterized by efficient matches but there can be additional equilibria with coordination failures

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

aggregation and imperfect competition on the existence of equilibrium we present a new approach to the theory of imperfect competition and apply it to study price competition among differentiated products the central result provides general conditions under which there exists a pure strategy price equilibrium for any number of firms producing any set of products this includes products with multi dimen sional attributes in addition to the proof of existence we provide conditions for uniqueness our analysis covers location models the characteristics approach and probabilistic choice together in a unified framework to prove existence we employ aggregation theorems due to prekopa 1971 and borell 1975 our companion paper caplin and nalebuff 1991 introduces these theorems and develops the application to super majority voting rules we present a new approach to the theory of imperfect competition and apply it to study price competition among differentiated products the central result is that there exists a pure strategy price equilibrium for any number of firms producing any set of products in addition to the proof of existence we provide conditions for uniqueness our model both unites diverse strands of the earlier literature and opens up uncharted areas for future analysis in particular we expand the traditional one dimensional framework to allow for multi dimen sional product differentiation our approach involves twin restrictions on consumer preferences one on individuals preferences the other on the distribution of preferences across society these are generalizations of the restrictions supporting 64 majority rule presented in caplin and nalebuff 1988 to prove existence we apply a new technique of aggregation this technique is valuable in a variety of other problems in the companion paper we use the aggregation result to generalize our earlier work on 64 majority rule and to characterize the relationship between the distribution of human capital and the distribution of income caplin and nalebuff 1991 there are additional applications in statistics and in search theory we begin with a brief review of the early literature on imperfect competition describing in more detail the existence problem and previous solutions section 3 presents our twin assumptions and shows that they cover many standard cases in section 4 we introduce the aggregation theorem and use it in the analysis of demand functions the proof of existence of equilibrium is in section

inventory sharing and rationing in decentralized dealer networks an increasing number of manufacturers have started to pursue a strategy that promotes inventory sharing among the dealers in their distribution network in this paper we analyze a decentralized dealer network in which each independent dealer is given the flexibility to share his inventory we model inventory sharing as a multiple demand classes problem in which each dealer faces his own customer demand with high priority and inventory sharing requests from other dealers with low priority assuming that each dealer uses a base stock and threshold rationing policy for his inventory stocking and inventory sharing decisions we explicitly model the interactions between the dealers through inventory sharing and obtain aclosed form cost function for each dealer based on the steady state distribution of the inventory levels at the two dealers we then provide a detailed supermodularity analysis of the inventory sharing and inventory rationing game in which each dealer has a two dimensional strategy set stocking level and rationing level we show that the full sharing game in which dealers precommit to sharing all of their on hand inventory and the fixed sharing level game in which dealers precommit to sharing a portion of their on hand inventory are supermodular and thus a pure strategy nash equilibrium is guaranteed to exist for the rationing game in which dealers precommit to their stocking levels we show that there exists a dominant strategy equilibrium on the dealers sharing rationing levels finally a comprehensive computational study is conducted to highlight the impact of the manufacturer s incentives subsidies and or transshipment fees on the dealers sharing behavior

estimation of complete demand systems from household budget data the linear and quadratic expenditure systems in this paper we explore two issues in empirical demand analysis the estimation of complete systems of demand equations using household budget data section i and the incorporation of demographic characteristics into such systems section ii although there are numerous studies which use time series data to estimate complete demand systems and many which estimate engel curves from household budget data there are virtually none which combine budget data from different periods to estimate complete systems since each budget study corresponds to a single price situation one might conjecture that estimation of complete systems would not be possible unless budget studies were available from a large number of periods this is incorrect in section i we argue that interesting complete demand systems can be estimated from a small number of budget studies despite the limited price variability represented in such data to demonstrate this we use budget study data for two periods to estimate a pair of related demand systems the familiar linear expenditure system les and a quadratic expenditure system qes a generalization of les in which the demand equations are quadratic in total expenditure the inclusion of demographic variables in the analysis of household consumption patterns is desirable because there are likely to be systematic differences in the consumption behavior of households with different demographic characteristics but the effects of demographic characteristics have seldom been studied within the framework of complete demand systems in section ii we propose translating as a general method for incorporating demographic variables into complete systems of demand equations this method has not previously been discussed as a general technique for bringing demographic variables into demand systems although it has been employed in several studies to improve the estimates of the les and the qes presented in section i we reestimate these two systems using translating to incorporate family size