but who will monitor the monitor suppose that providing incentives for a group of individuals in a strategic context requires a monitor to detect their deviations what about the monitor s deviations to address this question i propose a contract that makes the monitor responsible for monitoring and thereby provides incentives even when the monitor s observations are not only private but costly too i also characterize exactly when such a contract can provide monitors with the right incentives to perform in doing so i emphasize virtual enforcement and suggest its implications for the theory of repeated games jel c78 d23 d82 d86

a note on competitive investment under uncertainty uncertainty over future output prices or input costs can affect investment by a riskneutral firm in two opposing ways first it can increase the value of the marginal unit of capital which leads to more investment this only requires that the stream of future profits generated by the marginal unit be a convex function of the stochastic variable by jensen s inequality the expected present value of that stream is increased this result was demonstrated by richard hartman 1972 and later extended by andrew abel 1983 and others in their models constant returns to scale and the substitutability of capital with other factors ensure that the marginal profitability of capital is convex in output price and input costs even with fixed proportions however this convexity can result from the ability of the firm to vary output so that the marginal unit of capital need not be utilized at times when the output price is low or input costs are high if investment is irreversible and can be postponed a second effect of uncertainty is to create an opportunity cost of investing now rather than waiting for new information to arrive before committing resources this increases the full cost of investing in a marginal unit of capital which reduces investment 2 hence the net effect of uncertainty on irreversible investment depends on the size of this opportunity cost relative to the increase in the value of the marginal unit of capital the sign of the net effect is significant because of its possible policy implications pindyck 1988 and giuseppe bertola 1989 developed models in which a firm faces a downward sloping demand curve and found the net effect to be negative ricardo caballero 1991 has recently studied investment by an individual firm facing a stochastically shifting demand curve he shows that as returns to scale become constant and the elasticity of demand faced by the firm rises this opportunity cost of investing now rather than waiting approaches zero thus in the limit of constant returns and an infinitely elastic demand curve an increase in uncertainty tends to raise rather than decrease current investment even if that investment is irreversible it is important to stress that caballero s limiting result treats the firm in isolation and describes the effect of a meanpreserving increase in price uncertainty and not an increase in industry wide demand uncertainty this note shows that in a competitive market the key interactions between irreversibility and uncertainty occur at the industry level and can only be understood by making price and industry output endogenous 3 doing so restores the positive opportunity cost associated with irreversible investment in addition caballero s result is based on a model with convex adjustment costs an innovative aspect of the model is that these costs can be asymmetric thereby allowing for partial or complete irreversibility complete irreversibility corresponds to a cost of massachusetts institute of technology cambridge ma 02139 this work was supported by the national science foundation under grant no ses 8618502 and by mit s center for energy policy research my thanks to julio rotemberg and especially ricardo caballero for very helpful comments and discussions 1then the marginal profit of capital at each time t in the future is max o pt ct where ct is variable cost thus a unit of capital represents a set of all options on future production which are worth more the greater the variance of pt or ct 2for a detailed discussion of this point and a survey of the recent literature on irreversibility and its implications for investment and market evolution see pindyck 1991 3studies that make price endogenous include steven lippman and richard rumelt 1985 avinash dixit 1989 1991 and john leahy 1990

investment uncertainty and liquidity we analyze the dynamic investment decision of a firm subject to an endogenous financing constraint the threat of future funding shortfalls lowers the value of the firm s timing options and encourages acceleration of investment beyond the first best optimal level as well as highlighting another way by which capital market frictions can distort investment behavior this result implies that 1 the sensitivity of investment to cash flow can be greatest for high liquidity firms and 2 greater uncertainty has an ambiguous effect on investment

evidence on corporate hedging policy this paper provides empirical evidence on the determinants of corporate hedging decisions the paper examines the evidence in light of currently mandated financial reporting require ments and in particular the constraints placed on anticipatory hedging data on hedging are obtained from 1992 annual reports for a sample of 3 022 firms out of the 771 firms classified as hedgers 543 firms disclose information in their annual reports on their hedging activities the remaining 228 firms report use of derivatives but no information on hedging activities based on the evidence i draw the following conclusions with respect to the models of hedging evidence is inconsistent with financial distress cost models evidence is mixed with respect to contracting cost capital market imperfections and tax based models and evidence uniformly supports the hypothesis that hedging activities exhibit economies of scale

efficiency in repeated prisoner s dilemma with private monitoring abstract this paper analyzes repeated games with private monitoring where in each period each player receives a signal of the other player s action in the previous period and that signal is private information previous literature on discounted repeated games with private monitoring has not shown whether or not nearly efficient equilibria exist for a repeated prisoner s dilemma satisfying a certain assumption regarding stage game payoffs we show that there exists a nearly efficient sequential equilibrium provided that imperfectness of signals is small and players are patient journal of economic literature classification number c73

communication in repeated games with private monitoring abstract the paper considers repeated games where each player can be observed by only a subset of the other players and where players can make public announcements about the behavior of the players they observed we address the following question what is the minimal level of observability that is required to obtain efficient outcomes the main result is that the limit set of sequential equilibrium payoffs when the discount factor tends to one contains the set of individual rational payoffs whenever each player is observed by at leasttwoother players journal of economic literatureclassification number c73

hedging and liquidity this article develops a model for evaluating alternative hedging strategies for financially constrained firms a key advantage of the model is the ability to capture the intertemporal effects of hedging on the firm s financial situation we characterize the optimal hedge a wide range of alternative hedging strategies can be specified and the model allows us to determine in each case if the hedging strategy raises or lowers firm value and by how much we show that hedging firm value hedging cash flow from operations and hedging sales revenue are not optimal the article highlights the fact that every hedging strategy comes packaged with a borrowing strategy which requires careful consideration futures markets often provide the most liquid and convenient instruments for managing risk however because futures contracts are marked to market it is often impossible to simultaneously hedge cash flows and values for example a futures contract that locked in the value of gold that a corporation planned to extract in one year would generate an uncertain cash flow pattern over the year this article examines how liquidity and cash flow timing problems associated with different hedging strategies can affect a firm s value in our model the objective for hedging is to increase the firm s financial flexibility an optimal hedge maximizes the firm s liquidityslack in the form of excess cash or unused debt capacitywhen liquidity is most valuable this lowers the danger of costly financial distress reduces the effective cost of external financial constraints and makes value maximizing investments affordable a firm with no financial constraints does not gain from hedging and the higher the firm s financial constraints the greater the potential value of hedging the value of hedging depends critically on the design of the hedging strategy we show that the optimal hedge minimizes the variability in the marginal value of the firm s cash balances such a hedge efficiently redistributes cash balances across different states and periods taking cash from those states for which the marginal cost of the financial constraint is low and giving cash to those states for which the marginal

uncertain dynamics correlation effects and robust investment decisions abstract we analyze a firm s investment problem when the dynamics of project value and investment cost are uncertain we provide an explicit solution using a robust method for an ambiguity averse firm taking this into account ambiguity aversion regarding a common risk factor impacts differently than ambiguity aversion regarding investment cost residual risk correlation between project value and investment cost matters ambiguity aversion regarding common risk can decrease the investment probability only if correlation is positive ambiguity aversion regarding residual risk always increases the investment probability when only project value is risky volatility can monotonically decrease the investment threshold this does not hold with the multiple prior method

time to build option value and investment decisions a comment abstract we correct the analysis of the model of time to build in majd and pindyck 1987 journal of financial economics 18 7 27 for the omission of an essential optimality condition our analysis reveals an additional insight long times to build reduce the effects of increased project value volatility i e higher investment thresholds in comparison to standard real option models of investment under uncertainty where investment is instantaneous thus a naive npv rule can sometimes be an appropriate initial guide to investment

nash equilibria of repeated games with observable payoff vectors abstract we study a model of repeated games with imperfect monitoring where the payoff vector is observable in this situation any profitable deviation is detectable by all the players but the identity of the deviator may be unknown we design collective punishments directed against the set of potential deviators a particular class of signals is studied for which a characterization of the set of equilibrium payoffs is obtained journal of economic literature classification numbers c73

collusion and price rigidity we consider an in nitely repeated bertrand game in which prices are publicly observed and each rm receives a privately observed i i d cost shock in each period we focus on symmetric perfect public equilibria sppe wherein any punishments are borne equally by all rms we identify a tradeoff that is associated with collusive pricing schemes in which the price to be charged by each rm is strictly increasing in its cost level such fully sorting schemes offer efficiency bene ts as they ensure that the lowest cost rm makes the current sale but they also imply an informational cost distorted pricing and or equilibrium path price wars since a higher cost rm must be deterred from mimicking a lower cost rm by charging a lower price a rigid pricing scheme where a rm s collusive price is independent of its current cost position sacri ces efficiency bene ts but also diminishes the informational cost for a wide range of settings the optimal symmetric collusive scheme requires i the absence of equilibrium path price wars and ii a rigid price if rms are sufficiently impatient however the rigid pricing scheme cannot be enforced and the collusive price of lower cost rms may be distorted downward in order to diminish the incentive to cheat when the model is modi ed to include i i d public demand shocks the downward pricing distortion that accompanies a rm s lower cost realization may occur only when current demand is high

on the determinants of corporate hedging finance theory indicates that hedging increases firm value by reducing expected taxes expected costs of financial distress or other agency costs this paper provides evidence on these hypotheses using survey data on firm s use of forwards futures swaps and options combined with computstat data on firm characteristics of 169 firms in the sample 104 firms use hedging instruments in 1986 the data suggest that firms which hedge face more convex tax functions have less coverage of fixed claims are larger have more growth options in their investment opportunity set and employ fewer hedging substitutes

real flexibility and financial structure an empirical analysis i examine the empirical relation between real flexibility and financial structure i test whether real flexibility increases debt capacity by lowering default risk and making assets more marketable or decreases debt capacity by facilitating risk shifting and asset substitution i measure real flexibility as the sensitivity of marginal production and investment decisions to variations in the economic environment i find that financial leverage is negatively related to production flexibility but positively related to investment flexibility this split in results suggests that although asset substitution facilitated by investment flexibility can be prevented contractually risk shifting facilitated by production flexibility is intractable copyright 2003 oxford university press

a belief based approach to the repeated prisoners dilemma with asymmetric private monitoring abstract this paper extends the belief based approach to the repeated prisoners dilemma with asymmetric private monitoring we first find that the previous belief based techniques t sekiguchi efficiency in repeated prisoners dilemma with private monitoring j econ theory 76 1997 345 361 v bhaskar i obara belief based equilibria in the repeated prisoners dilemma with private monitoring j econ theory 102 2002 40 69 cannot succeed when players private monitoring technologies are sufficiently different we then modify the previous belief based approach by letting the player with smaller observation errors always randomize between cooperate and defect along the cooperative path of the play we show that with vanishing observation errors efficiency and a folk theorem can be approximated using our modified belief based strategies

strategic buyers and privately observed prices a model of finitely repeated price competition between two sellers with differentiated goods and a large buyer is analyzed the set of pure strategy sequential equilibria is investigated under public and private monitoring with private monitoring i e when prices are not observable to the competing sellers all sales are made by the better seller and the set of repeated game equilibrium payoffs coincides with the stage game subgame perfect equilibrium payoffs this is in sharp contrast to the game with perfect monitoring where the folk theorem obtains journal of economic literature classification numbers c72 d43

robustness of public equilibria in repeated games with private monitoring a repeated game with private monitoring is close to a repeated game with public monitoring or perfect monitoring when i the expected payoff structures are close and ii the informational structures are close in the sense that private signals in the private monitoring game can be aggregated by some public coordination device to generate a public signal whose distribution is close to the distribution of the public signal in the public monitoring game we provide a sufficient condition for the set of uniformly strict perfect public equilibria for a public monitoring game to be robust in nearby private monitoring games in the sense that they remain equilibria with respect to the public signal that is generated by such public coordination devices with truthful reporting our sufficient condition requires that every player is informationally small in a well defined sense

on failing to cooperate when monitoring is private abstract i consider a repeated prisoners dilemma where in each period each player receives an imperfect private signal about his opponent s current action i show that when players are patient enough any equilibrium where players use trigger strategies i e do not revert to cooperation once they have started defecting yields players a value arbitrarily close to the mutual minimax i also examine the robustness of the result to perturbations of the game journal of economic literature classification numbers c72

energy growth conundrum in energy exporting and importing countries evidence from heterogeneous panel methods robust to cross sectional dependence abstract this article uses the panel methods for energy exporting and importing countries that discuss the heterogeneity and cross sectional dependence in investigating the linkages between energy consumption and economic growth the findings of the study suggest that the energy consumption is an important input not only in the energy importing but also in energy exporting countries furthermore the results of the present paper suggest that the policy options should be different for the different countries in the back drop of heterogeneous slope coefficients

interactions of corporate financing and investment decisions a dynamic framework this article analyzes the interaction between a firm s dynamic investment operating and financing decisions in a model with operating adjustment and recapitalization costs using numerical analysis we solve the model for cases that highlight interaction effects we find that higher production flexibility due to lower costs of shutting down and reopening a production facility enhances the firm s debt capacity thereby increasing the net tax shield value of debt financing while higher financial flexibility resulting from lower recapitalization costs has a similar effect production flexibility and financial flexibility are to some extent substitutes we find that the impact of debt financing on the firm s investment and operating decisions is economically insignificant

communication in repeated games with imperfect private monitoring this paper examines repeated games in which each player observes a private and imperfect signal on the actions played and in which players are allowed to communicate using public messages providing incentives for players to reveal their observations generates revelation constraints that combined with signal imperfections may be a source of inefficiencies however by delaying the revelation of their observations players may economize on the cost of deterring deviations and thereby avoid these inefficiencies because a player would not want to trigger a sanction that would penalize him too revelation constraints also tend to make sanctions difficult to enforce however with at least three players detecting deviations may not require that all the players reveal their observations in that case we obtain a nash threat version of the folk theorem with two players we do not obtain a similar result nevertheless we show that an efficient outcome can almost always be approximated

private monitoring in auctions abstract we study infinitely repeated first price auctions in which a bidder only learns whether or not he won the object while repetition of the stage game equilibrium is the unique nash equilibrium in public strategies with patient bidders there are simple nash equilibria in private strategies that improve on bid rotation sequential rationality is appropriately captured by essentially perfect bayesian equilibrium epbe which ignores behavior after irrelevant histories our main result is the construction of epbea that improve upon bid rotation assuming symmetry the exclusionary schemes of skrzypacz and hopenhayn tacit collusion in repeated auctions j econ theory 114 2004 153 169 including asymptotically efficient ones are supported as epbea

an integrated model of multinational flexibility and financial hedging abstract we construct a model of a multinational firm with flexibility in sourcing its production and with the ability to use financial markets to hedge exchange rate risk agency costs generated by the firm s capital structure create a link between the firm s financial policy and its production decisions the firm s need for hedging is directly related to the degree of flexibility and the production plan it chooses is a function of the hedging strategy it employs consequently the firm s ability to exploit its competitive position depends upon the degree to which its flexibility is matched by the construction of an appropriate hedging strategy

hedging the value of waiting abstract we analyze the optimal hedging policy of a firm that has flexibility in the timing of investment conventional wisdom suggests that hedging adds value by alleviating the under investment problem associated with capital market frictions however our model shows that hedging also adds value by allowing investment to be delayed in circumstances where the same frictions would cause it to commence prematurely thus hedging can have the paradoxical effect of reducing investment we also show that greater timing flexibility increases the optimal quantity of hedging but has a non monotonic effect on the additional value created by hedging these results may help explain the empirical findings that investment rates do not differ between hedgers and non hedgers and that hedging propensities do not depend on standard measures of growth opportunities

efficiency in partnerships with joint monitoring abstract this paper examines deterministic partnerships where a single partner observes the actions taken by a subset of the other partners and issues a report conditional on that observation no other partner has any additional information in such a model whenever the observing partner can see the action chosen by at least one other partner the efficient action vector can be sustained in a perfect bayesian equilibrium by sharing rule that exhibits budget balance and limited liability journal of economic literature classification numbers c7 d7 d8 l2

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

a limit characterization of belief free equilibrium payoffs in repeated games abstract the present paper studies repeated games with private monitoring and characterizes the set of belief free equilibrium payoffs in the limit as the discount factor approaches one and the noise on private information vanishes contrary to the conjecture by ely et al j c ely j horner w olszewski belief free equilibria in repeated games econometrica 73 2005 377 415 the equilibrium payoff set is computed by the same formula no matter how many players there are as an application of this result a version of the folk theorem is established for n player prisoner s dilemma games

perfect communication equilibria in repeated games with imperfect monitoring this paper introduces an equilibrium concept called perfect communication equilibrium for repeated games with imperfect private monitoring this concept is a refinement of myerson s myerson r b 1982 optimal coordination mechanisms in generalized principal agent problems j math econ 10 67 81 communication equilibrium a communication equilibrium is perfect if it induces a communication equilibrium of the continuation game after every history of messages of the mediator we provide a characterization of the set of corresponding equilibrium payoffs and derive a folk theorem for discounted repeated games with imperfect private monitoring

globalisation and sustainability environmental kuznets curve and the wto abstract economic globalisation is seen by many as a driving force for global economic growth yet opinion is divided about the benefits of this process as highlighted by the wto meeting in seattle in late 1999 proponents of economic globalisation view it as a positive force for environmental improvement and as a major factor increasing the likelihood of sustainable development through its likely boost to global investment these proponents mostly appeal to analysis based on the environmental kuznets curve ekc to support their views about environmental improvement but ekc analysis has significant deficiencies furthermore it is impossible to be confident that the process of economic globalisation will result in sustainable development if weak conditions only are satisfied strong conditions probably need to be satisfied to achieve sustainable development and given current global institutional arrangements these are likely to be violated by the economic globalisation process global political action seems to be needed to avert a deterioration in the global environment and to prevent unsustainability of development this exposition demonstrates the limitations of ekc analysis identifies positive and negative effects of economic globalisation on pollution levels and highlights connections between globalisation and the debate about whether strong or weak conditions are required for sustainable development the article concludes with a short discussion of the position of wto in relation to trade and the environment and the seemingly de facto endorsement of wto of weak conditions for sustainable development it suggests that wto s relative neglect of environmental concerns is no longer politically tenable and needs to be reassessed in the light of recent developments in economic analysis the skew of economic growth e g in favour of developing countries is shown to be extremely important from a global environmental perspective

credible communication in dynastic government abstract this paper studies information disclosure in a model of dynastic government when information about past policy choices comes exclusively from the reports of previous administrations each administration has an incentive to choose its suboptimal one shot expenditure policy and then misrepresent its choice to its successor consequently it has been suggested that horizontal accountability i e a system of governance where auditing functions lie outside the executive branch can ensure credible disclosure of a government s activities this paper suggests a cautious approach to that view the baseline model examines the reporting incentives of an external auditor who can independently verify the information each period even with auditing credible disclosure is shown to be problematic various extensions to this baseline model are examined in one extension liberal i e those prefering larger government expenditures and conservative those prefering smaller expenditures regimes and auditors evolve over time it is shown that conservative liberal auditors are not credible when the current regime is also conservative liberal moreover because information transmission stops when the auditor s and the regime s biases coincide effective deterrents even in the good periods when the auditor s and the administration s biases differ are difficult to construct in all periods the equilibrium requirement of auditor neutrality constrains the dynamic incentives for efficient policy choices these constraints are shown to bind away from optimal policies in standard constructions of equilibrium various ways in which auditing protocols can overcome these problems are discussed

introduction to repeated games with private monitoring abstract we present a brief overview of recent developments in discounted repeated games with imperfect private monitoring the literature explores the possibility of cooperation in a long term relationship where each agent receives imperfect private information about the opponents actions although this class of games admits a wide range of applications such as collusion under secret price cutting exchange of goods with uncertain quality and observation errors it has fairly complex mathematical structure due to the lack of common information shared by players this is in sharp contrast to the well explored case of repeated games under public information with the celebrated folk theorems and until recently little had been known about the private monitoring case however rapid developments in the past few years have revealed the possibility of cooperation under private monitoring for some class of games journal of economic literature classification numbers c72 c73 d43 d82 l13 l41

unmediated communication in repeated games with imperfect monitoring we show that any correlated equilibrium payoff of two player repeated games with imperfect monitoring and without discounting can be reached as the nash equilibrium payoff of the game extended by a universal mechanism of unmediated communication this result holds regardless the particular concept of equlibrium involved upper lower banach or uniform equlibrium the communication mechanism is built up by using commutative one way functions these functions are designed with the help of cryptographic tools

collusion in dynamic bertrand oligopoly with correlated private signals and communication abstract this paper studies collusion in repeated bertrand oligopoly when stochastic demand levels for the product of each firm are their private information and are positively correlated it derives general sufficient conditions for efficient collusion through communication and a simple grim trigger strategy this analysis is then applied to a model where the demand signal has multiple random components which respond differently to price deviations in this model it is shown that the above sufficient conditions hold if idiosyncratic noise terms are sufficiently small journal of economic literature classification numbers c72 d82

the repeated prisoner s dilemma with imperfect private monitoring abstract in this paper i study a repeated prisoner s dilemma game in which monitoring is private and imperfect a partial folk theorem is proved for the case of almost perfect monitoring

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

communication in repeated games with costly monitoring abstract we study repeated games with discounting where perfect monitoring is possible but costly it is shown that if players can make public announcements then every payoff vector which is an interior point in the set of feasible and individually rational payoffs can be implemented in a sequential equilibrium of the repeated game when the discount factor is high enough thus efficiency can be approximated even when the cost of monitoring is high provided that the discount factor is high enough

on sustaining cooperation without public observations abstract this paper examines a dynamic game in which each player only observes a private and imperfect signal on the actions played our main result is that in a repeated prisoner s dilemma where defections are irreversible at least for a long enough period of time patient enough players may achieve almost efficient outcomes dealing with models of imperfect private monitoring is difficult because i continuation games are games of incomplete information hence they do not have the same structure as the original game in particular continuation equilibria are correlated equilibria ii players are typically uncertain about their opponents past observations and actions and they use their entire own private history to learn about these actions as a result equilibrium strategies are in general nontrivial and increasingly complex functions of past observations we bypass these difficulties by looking at correlated equilibria of the original game and find correlated equilibria in which the decision problem faced by each player remains the same over time journal of economic literature classification numbers c72

natural resources and the tradeoff between authoritarianism and development abstract why do african and middle eastern countries seem cursed by an abundance of natural resources yet usa australia and norway seem blessed a growing literature has argued that the benevolence or malignance of natural resources depends upon the quality of institutions this paper offers a new explanation based on associational freedom and its interaction with the political system the model predicts that natural resources have an adverse impact on economic performance and transition to democracy in authoritarian regimes but not in democracies it also predicts that repression of associational freedom will be increasing in natural resources in authoritarian regimes i test the model s predictions using fixed effects regressions on an international panel from 1975 to 2000 and find support

sources of emission reductions market and policy stringency effects abstract international trade and economic development affect air emissions previous studies have decomposed their effects into scale composition and technique effects while the scale and composition effects occur through market responses the technique effect is a policy stringency influence through the mix of environmental policies this study analyzes whether the market or policy stringency effects are more prominent previous studies have been unable to adequately separate the market and policy stringency effects to independently measure the technique effect we use two indicators of policy stringency i e shadow prices of energy and industrial energy prices these policy stringency measures are treated as endogenous the effects on six types of air emissions are estimated utilizing a sector specific international panel dataset that includes newly industrialized and former transition economies the empirical results show that the major source of emissions reductions is the policy stringency effect through carbon related policies pollution offshoring to countries with weaker carbon related regulation has a minor role in the reduction of air emissions

the folk theorem for repeated games with observation costs abstract the folk theorem literature has been relaxing the assumption on how much players know about each other s past action here we consider a general model where players can buy precise information every period each player decides whether to pay a cost to accurately observe the actions chosen by other players in the previous period when a player does not pay the cost he obtains only imperfect private signals observational decisions are unobservable to others known strategies such as trigger strategies do not work since they fail to motivate players to pay for information this paper shows that the folk theorem holds for any level of observation costs unlike existing folk theorems with private monitoring ours imposes virtually no restriction on the nature of costless imperfect signals the theorem does not use explicit or costless communication thereby having implications on antitrust laws that rely on evidence of explicit communication the main message is that accurate observation alone however costly enables efficient cooperation in general repeated games

optimal dynamic trading with leverage constraints we solve for the optimal dynamic trading strategy of an investor who faces a leverage constraint i e a limitation on his ability to borrow for the purpose of investing in a risky asset we assume that the investor has constant relative risk aversion and that the value of the risky asset follows a geometric brownian motion in the absence of the leverage constraint the optimal strategy involves investing a fixed proportion of wealth in the risky asset we prove that in the presence of the leverage constraint the optimal investment also involves investing a fixed proportion of wealth in the risky asset when the leverage constraint is not binding however the two proportions are different reflecting the extent to which the investor alters his strategy even when the leverage constraint is not binding because of the possibility that the leverage constraint will become binding in the future