employment based analysis an alternative methodology for project evaluation in developing regions with an application to agriculture in yucatan abstract governmental and non governmental organizations ngos in developing regions increasingly recognize the links between sustainable development and environmental protection for this reason environmental protection efforts in these regions increasingly include sustainable community development projects unlike most traditional large scale development projects the objective of such projects is to give local inhabitants sustainable economic alternatives to environmentally degrading activities rather than to maximize the flow of discounted net benefits the traditional method of project evaluation cost benefit analysis cba does not provide useful information regarding the meeting of such objectives the purpose of this paper is to introduce discuss and provide a brief example of employment based analysis eba as a means of project evaluation in developing countries in contrast to the cba approach of measuring a discounted flow of net benefits from economic options eba measures the number of jobs or population support provided by alternative activities using a given resource typically land over a given period of time eba better incorporates sustainability into project analysis by avoiding the use of discounting directly linking project success with environmental sustainability and penalizing economic activities that involve income inequality and income capital flight eba is particularly illuminating when applied to small scale sustainable development projects that are part of environmental conservation programs after a brief description of the methodology the motivation strengths and weaknesses of eba are discussed a simple application of eba and cba to alternative agricultural activities traditional farming improved farming and cattle ranching in yucatan mexico is then provided this analysis indicates that while cattle ranching has a higher benefit cost ratio both traditional and improved farming provide more population support and greater contributions to sustainability this example serves to highlight the potential benefits to using eba instead of or in conjunction with cba in developing regions along with highlighting some of the strengths and challenges of eba

decentralized trading strategic behaviour and the walrasian outcome for a market with a finite number of agents pairwise matching and bargaining it is shown that even when the market is frictionless the equilibrium is not necessarily competitive it depends on the amount of information agents use if their behaviour is conditioned only on the sets of agents present and the time the competitive solution is the unique subgame perfect equilibrium if agents have full information and condition their behaviour on some of it there are also noncompetitive equilibria in which behaviour depends on specific information such as the identity of the trading partner and past events

a two sided reputation result with long run players abstract we establish reputation results under two sided incomplete information for a class of repeated games we consider a repeated game that satisfies the assumptions of either atakan and ekmekci 2012 3 or cripps et al 2005 6 and we assume that both players are stackelberg types with positive probability if the stage game is not a common interest game then equilibrium play converges to the unique equilibrium of a continuous time war of attrition as the stage game is repeated arbitrarily frequently alternatively if the stage game is a common interest game then the players equilibrium payoffs converge to their highest payoffs as the stage game is repeated arbitrarily frequently

age dynamics and economic growth revisiting the nexus in a nonparametric setting abstract nonparametric panel regressions between economic growth and age structured population for oecd and non oecd countries show significant non linear relationship contributing to their growth volatilities over the 1960 2000 period with interesting current and feedback effects

bargaining and reputation an experiment on bargaining in the presence of behavioural types we conduct a series of laboratory experiments to understand what role commitment and reputation play in bargaining the experiments implement the abreu and gul 2000 bargaining model that demonstrates how introducing behavioral types which are obstinate in their demands creates incentives for all players to build reputations for being hard bargainers the data are qualitatively consistent with the theory as subjects mimic induced types furthermore we find evidence for the presence of complementary types whose initial demands acquiesce to induced behavioural demands however there are quantitative deviations from the theory subjects make aggressive demands too often and participate in longer conflicts before reaching agreements overall the results suggest that the abreu and gul 2000 model can be used to gain insights to bargaining behavior particularly in environments where the process underlying obstinate play is well established

bargaining with two sided incomplete information an infinite horizon model with alternating offers this paper examines an infinite horizon bargaining model incorporating five features two sided incomplete information with potentially information revealing strategies an infinite horizon uncertainty concerning the potential gains from trade an illumination of interesting qualitative bargaining issues and plausible free from arbitrarily specified out of equilibrium conjectures equilibria these features motivated in the paper have powerful implications a nash equilibrium exists and is generically both unique and sequential comparative static implications of variations in the game s specifications are developed we find that natural indications of bargaining strength emerge from the model and establish the intuitive result that an increase in a player s relative bargaining strength makes that player more likely to capture the gains from bargaining

matching markets with adverse selection abstract this paper considers a market with adverse selection in the spirit of rothschild and stiglitz quart j econ 90 1976 629 the major departure from existing approaches is that we model a decentralized market that is open ended and constantly refilled by new participants e g by new workers and firms in the case of a labor market the major novelty of this approach is that the distribution of types in the market becomes an endogenous variable which is jointly determined with equilibrium contracts as frictions become small we show that the least cost separating contracts are always supported as an equilibrium outcome regardless of the distribution of types among entrants moreover we derive conditions under which this outcome is also unique

demographic structure and capital accumulation a quantitative assessment abstract in a recent paper d albis 2007 demographic structure and capital accumulation journal of economic theory 132 411 434 shows that the effect of population growth on capital accumulation is ambiguous in overlapping generations models with age specific mortality rates contrasting to the predicted negative effect in diamond 1965 national debt in a neoclassical growth model american economic review 55 1126 1150 and blanchard 1985 debt deficits and finite horizons journal of political economy 93 223 247 the quantitative exercises of this paper indicate that while in principle a positive relation between population growth and capital accumulation is possible this relation is practically always negative for industrial countries intuition based on capital dilution and aggregate saving effects is provided this paper also complements d albis 2007 demographic structure and capital accumulation journal of economic theory 132 411 434 in characterizing the steady state equilibrium in more familiar economic concepts

reputation and imperfect information abstract a common observation in the informal literature of economics and elsewhere is that is multistage games players may seek early in the game to acquire a reputation for being tough or benevolent or something else but this phenomenon is not observed in some formal game theoretic analyses of finite games such as selten s finitely repeated chain store game or in the finitely repeated prisoners dilemma we reexamine selten s model adding to it a small amount of imperfect or incomplete information about players payoffs and we find that this addition is sufficient to give rise to the reputation effect that one intuitively expects

dynamic matching and bargaining games a general approach this paper presents a new characterization result for competitive allocations in quasilinear economies this result is informed by the analysis of non cooperative dynamic search and bargaining games such games provide models of decentralized markets with trading frictions a central objective of this literature is to investigate how equilibrium outcomes depend on the level of the frictions in particular does the trading outcome become walrasian when frictions become small existing specifications of such games provide divergent answers the characterization result is used to investigate what causes these differences and to generalize insights from the analysis of specific search and bargaining games

rising longevity education savings and growth this paper examines the impact of declines in adult mortality on growth in an overlapping generations model with public education and imperfect annuity markets a decline in mortality affects growth through three channels first it raises the saving rate and thereby increases the rate of physical capital accumulation second it reduces accidental bequests lowers investment and thereby lowers the rate of physical capital accumulation third it may lead the median voter to increase the tax rate for public education initially but lower the tax rate in a later stage starting from a high mortality rate as found in many third world populations the net effect of a decline in mortality is to raise the growth rate however starting from a low mortality rate such as is found in most industrial populations the net effect of a further decline in mortality is to reduce the growth rate the findings appear consistent with recent empirical evidence

bargaining and reputation the paper develops a reputation based theory of bargaining the idea is to investigate and highlight the influence of bargaining postures on bargaining outcomes a complete information bargaining model a la rubinstein is amended to accommodate irrational types who are obstinate and indeed for tractability assumed to be completely inflexible in their offers and demands a strong independence of procedures result is derived after initial postures have been adopted the bargaining outcome is independent of the fine details of the bargaining protocol so long as both players have the opportunity to make offers frequently the latter analysis yields a unique continuous time limit with a war of attrition structure in the continuous time game equilibrium is unique and entails delay consequently inefficiency the equilibrium outcome reflects the combined influence of the rates of time preference of the players and the ex ante probabilities of different irrational types as the probability of irrationality goes to zero delay and inefficiency disappear furthermore if there is a rich set of types for both agents the limit equilibrium payoffs are inversely proportional to their rates of time preference

no compromise uncertain costs in reputational bargaining abstract i show how uncertainty about agents future costs of delay can lead to substantial bargaining delays when agents have reputational concerns reputational concerns arise because with positive probability agents are behavioral types committed to demanding a fixed share of the surplus in equilibrium rational agents may demand almost the entire surplus and then wait with the deadlock only broken by the arrival of news about future costs even as the probability of behavioral types vanishes although both agents would benefit from a compromise reached immediately they do not propose such agreements because doing so would increase an opponent s option value of waiting

equilibrium in a market with sequential bargaining this paper considers a market where pairs of agents who are interested in carrying out a transaction are brought together by a stochastic process and upon meeting initiate a bargaining process over the terms of the transaction the basic bargaining problem is treated with the strategic approach the paper derives the steady state equilibrium agreements analyzes their dependence on market conditions such as the relative numbers of agents of different types and discusses their relations with the competitive equilibrium outcome and other results in the search equilibrium literature this paper considers a market that operates in the following way pairs of agents who have mutual interest in carrying out a transaction are brought together by a stochastic process when two agents meet they initiate a bargaining process over the terms of the transaction if two agents reach an agreement a transaction takes place and they leave the market of course the bargaining positions and hence the agreement reached in any particular meeting will be affected by the conditions prevailing in the market these will include the chances that each of the negotiating parties have of meeting other partners in the event that the agreement in the current negotiations is delayed also the expected length of time required to achieve an alternative transaction and the expected behavior of alternative partners the study of such a market mechanism is of interest for two reasons firstly it captures some realistic aspects of the trade in certain specific markets e g asset markets such as housing and some labor markets secondly it contributes to an understanding of the micro mechanisms of price formation and their role in shaping market outcomes in both cases the features studied are largely neglected in the traditional market equilibrium analyses the related literature includes the articles by diamond 4 5 diamond and maskin 6 mortensen 8 9 and zusman and bell 13 these articles consider markets of the type described above in which transactions are concluded at pairwise meetings of agents the major difference between our work and these articles is in the approach to the basic bargaining problem in the cited articles it is assumed that a meeting is concluded with an instantaneous agreement which divides the associated surplus in an arbitrary predetermined way when the surplus is assumed to be divided equally the division rule is in fact nash s axiomatic bargaining solution in contrast the present paper treats the basic bargaining problem with the strategic approach see rubinstein 19 which constitutes an attempt to look into the bargaining black box this approach explicitly models the time dimension of the bargaining process describes in detail the bargaining procedure and justifies the agreement as a perfect equilibrium in

bargaining with imperfect commitment abstract we study the effect of imperfect commitment in noncooperative two person bargaining games by establishing the reputation for being stubborn a player sometimes commits to her initial demand becoming unable to change her demands or to accept an inferior offer from her opponent when the probability of being stubborn is small the set of equilibria is shown to be small and agreement may be reached immediately despite the possibility of stubbornness a player has greater bargaining power when she is more patient and or is more likely to be stubborn journal of economic literature classification number c78

alternating offer bargaining with two sided incomplete information i study alternating offer bargaining games with two sided incomplete information about the players discount rates for both perfect bayesian equilibrium and a rationalizability style notion i characterize the set of expected payoffs which may arise in the game i also construct bounds on agreements that may be made the set of expected payoffs is easy to compute and incorporate into applied models my main result is a full characterization of the set of perfect bayesian equilibrium payoffs for games in which the distribution over the players discount rates is of wide support yet is in a weak sense close to a point mass distribution i prove a lopsided convergence result each player cannot gain from a slight chance that she is a strong type but the player can suffer greatly if there is a slight chance that she is a weak type

non cooperative bargaining theory an introduction the paper provides an informal introduction to some of the main themes of the recent literature on non cooperative or sequential bargaining models it focuses in particular on the relationship between the new approach and the traditional axiomatic approach exemplified by nash bargaining theory it illustrates the new insights offered by the non cooperative approach by reference to a detailed analysis of the manner in which the presence of an outside option available to one of the parties will affect the negotiated outcome finally the difficulties which arise in extending this analysis to two person bargaining with incomplete information and to n person bargaining are discussed this is a revised version of the fourth review of economic studies lecture presented in april 1985 at the joint meeting of the association of university teachers of economics and the royal economic society held in oxford the choice of lecturer is made by a panel whose members are currently professors hahn mirrlees and nobay and the paper is refereed in the usual way this paper aims to provide an informal and elementary introduction to an approach to bargaining which has received a great deal of attention over the past few years the approach involves writing down some particular sequence of moves offers and replies to be made over time in the course of negotiations and then looking for a non cooperative equilibrium in the game thus specified in practice a perfect equilibrium or in games of incomplete information a sequential equilibrium while the approach appears at first sight to be very different in spirit from the traditional axiomatic approach in which a bargaining solution is specified by appealing to a number of general requirements which are deemed appropriate on the basis of some a priori considerations the two approaches are in fact complementary while the

delay in trade networks we study decentralized markets involving producers and consumers that are facilitated by middlemen we do this by analyzing a noncooperative networked bargaining game we assume a complete information setup wherein all the agents know the structure of the network the values of the consumers and the transaction costs involved but allow for some search friction when either producers or consumers trade with middlemen in such a setting we show that sunk cost problems and a heterogeneous network can give rise to delay or failure in negotiation and therefore reduce the total trade capacity of the network in the limiting regime of extremely patient agents we provide a sharp characterization of the trade pattern and the segmentation of these markets

gambling reputation repeated bargaining with outside options we study the role of incomplete information and outside options in determining bargaining postures and surplus division in repeated bargaining between a long run player and a sequence of short run players the outside option is not only a disagreement point but reveals information privately held by the long run player in equilibrium the uninformed short run players offers do not always respond to changes in reputation and the informed long run player s payoffs are discontinuous the long run player invokes inefficient random outside options repeatedly to build reputation to a level where the subsequent short run players succumb to his extraction of a larger payoff but he also runs the risk of losing reputation and relinquishing bargaining power we investigate equilibrium properties when the discount factor goes to 1 and when the informativeness of outside options diffuses in both cases bargaining outcomes become more inefficient and the limit reputation building probabilities are interior publication abstract

demographic change human capital accumulation and r d based growth employing an overlapping generations model of r d based growth with endogenous fertility and education decisions we examine how demographic changes induced by an increase in life expectancy influence the long run growth rate of the economy we demonstrate that life expectancy when relatively low high positively negatively affects economic growth this paper also compares the growth implications of child education subsidy policies i e policies for enhancing basic education and child rearing subsidy policies i e pro natal policies and demonstrate that while the child education subsidies consistently foster economic growth child rearing subsidies may negatively affect economic growth

project analysis and the world bank the world bank has been the single most important international institution to promote the practice of professional project appraisal over the past five decades although at times conventional project lending has been a relatively small share of total lending by the world bank key members of the bank staff have continued to be active in improving the understanding of what creates success or failure in the performance of development projects their influence on governments and practitioners in this field has been significant and widespread this abstract was borrowed from another version of this item

electoral motives and the subnational allocation of foreign aid in sub saharan africa abstract this paper examines how electoral motives shape the subnational allocation of foreign aid commitments by employing a newly constructed geocoded dataset for 14 sub saharan african countries over the period 2000 2012 our results provide strong evidence of a core voter strategy african leaders diverting chinese aid towards regions with a high concentration of political supporters however no evidence of such preferential treatment is found for world bank aid suggesting that aid from traditional donors is less vulnerable to political manipulation our results also reveal that checks and balances in recipient countries are an important mediating factor of aid misallocation while copartisan regions receive larger amounts of chinese aid in environments with weak checks and balances these effects disappear when stronger checks and balances are in place this paper also offers case study evidence from ghana exploiting the 2009 regime change in ghana and using a difference in differences framework we provide further support of copartisan targeting and confirm that chinese aid is more manipulable than world bank aid in this respect

bargaining reputation and competition this paper addresses the question of whether playing the tough bargainer is a useful strategy for rational negotiators in competitive environments the unique equilibrium outcome of a continuous time multilateral bargaining game between a single seller and two buyers i e a three player war of attrition game show that it does not benefit the buyers the long side of the market if the probability of obstinacy is constant and independent of the initial demands this result is robust in the sense that the buyers heterogeneity about their flexibility does not weaken the intensity of the competition when the seller decides which buyer to negotiate first he not only chooses his bargaining partner but also picks his outside option the seller can strengthen his bargaining position against both buyers by picking the unattractive buyer who is greedier or tougher than the other buyer first and by leaving the attractive buyer aside because he starts the sequel with a strong outside option

demographic transition in resource rich countries a blessing or a curse summary this study argues that resource wealth is a key factor for understanding income effects of demographic transition we develop a simple model highlighting how the income effect of increased labor supply may depend on resource rents and provide empirical evidence that support the theoretical predictions using panel data covering the period from 1982 to 2006 for more than 120 countries we find a negative interaction effect between resource wealth and demographic transition on national income moreover the negative interaction effect does not depend on institutional quality and is found also across different samples

bargaining and reputation in search markets in a two sided search market agents are paired to bargain over a unit surplus the matching market serves as an endogenous outside option for a bargaining agent behavioral agents are commitment types that demand a constant portion of the surplus the frequency of behavioral types is determined in equilibrium even if the frequency of behavioral types is negligible they aect the terms of trade and eciency in an unbalanced market where the entering

a non cooperative bargaining model with strategically timed offers abstract rubinstein s alternating offers bargaining model is enriched by allowing players to choose when and whether or not to make an offer time is continuous and players make offers whenever they wish it is assumed that upon making an offer players must wait a fixed amount of time before making another it is shown that if players can react arbitrarily quickly to their opponent s offers then all subgame perfect equilibrium outcomes are rubinstein like in particular efficient however if it takes time to react then some delay can be supported this potential delay becomes arbitrarily large as reaction times increase journal of economic literature classification numbers c78 c72

predation reputation and entry deterrence abstract economists often argue that predatory practices are irrational since there exist cheaper or more certain means to gain or maintain a monopoly our gametheoretic equilibrium analysis suggests that if a firm is threatened by several potential entrants then predation may be rational against early entrants even if it is costly when viewed in isolation because it yields a reputation which deters other entrants asymmetric information plays a crucial role in our analysis since it provides the rationale for entrants to base their expectations of the firm s future behavior on its past actions the analysis also suggests methods to treat general reputational phenomena

bilateral trading and incomplete information price convergence in a small market abstract we study a model of decentralised bilateral interactions in a small market where one of the sellers has private information about her value in addition to this seller with private information there are two identical buyers and another seller whose valuation is commonly known to be in between the two possible valuations of the seller with private information we consider an infinite horizon game with simultaneous one sided offers and simultaneous responses we construct one particular pbe of the game and show that as the discount factor goes to 1 prices in all transactions converge to the same value we then show that this is the case with any stationary equilibrium of the game that is the asymptotic outcome is unique across all stationary equilibria

search with adverse selection this paper analyzes a sequential search model with adverse selection we study information aggregation by the price how close the equilibrium prices are to the full information prices when search frictions are small we identify circumstances under which prices fail to aggregate information well even when search frictions are small we trace this to a strong form of the winner s curse that is present in the sequential search model the failure of information aggregation may result in inefficient allocations

war and conflict in economics theories applications and recent trends we review the main economic models of war and conflict these models vary in details but their implications are qualitatively consistent highlighting key commonalities across a variety of conflict settings recent empirical literature employing both laboratory and field data in many cases confirms the basic implications of conflict theory however this literature also presents important challenges to the way economists traditionally model conflict we finish our review by suggesting ways to address these challenges

bargaining reputation and equilibrium selection in repeated games with contracts consider a two person intertemporal bargaining problem in which players choose actions and offers each period and collect payoffs as a function of that period s actions while bargaining proceeds this can alternatively be viewed as an infinitely repeated game wherein players can offer one another enforceable contracts that govern play for the rest of the game theory is silent with regard to how the surplus is likely to be split because a folk theorem applies perturbing such a game with a rich set of behavioral types for each player yields a specific asymptotic prediction for how the surplus will be divided as the perturbation probabilities approach zero behavioral types may follow nonstationary strategies and respond to the opponent s play in equilibrium rational players initially choose a behavioral type to imitate and a war of attrition ensues how much should a player try to get and how should she behave while waiting for the resolution of bargaining in both respects she should build her strategy around the advice given by the nash bargaining with threats nbwt theory developed for two stage games in any perfect bayesian equilibrium she can guarantee herself virtually her nbwt payoff by imitating a behavioral type with the following simple strategy in every period ask for and accept nothing less than that player s nbwt share and while waiting for the other side to concede take the action nash recommends as a threat in his two stage game the results suggest that there are forces at work in some dynamic games that favor certain payoffs over all others this is in stark contrast to the classic folk theorems to the further folk theorems established for repeated games with two sided reputational perturbations and to the permissive results obtained in the literature on bargaining with payoffs as you go

on the role of outside options in bargaining with obstinate parties the presence of obstinate types in bargaining has been shown to alter dramatically the bargaining equilibrium strategies and outcomes this paper shows that outside options may cancel out the effect of obstinacy in bargaining when parties have access to stationary outside options we show that when opting out is preferable to accepting the inflexible demand of the other party there is a unique perfect bayesian equilibrium in which each party reveals himself as rational as soon as possible a similar conclusion holds when outside options may only be available at a later date or when only one party has access to an outside option

demographic change and economic growth an inverted u shape relationship abstract the cross country regression and non parametric kernel estimation using the panel data from oecd countries over the 1960 2000 periods show the inverted u shape relationship between demographic changes and economic growth growth rates initially increase and then decrease with population aging

durable goods monopoly with entry of new consumers this paper analyzes a model of a dynamic monopolist who produces at constant unit cost each period a new cohort of consumers enters the market each entering cohort is identical consumers within a cohort have different tastes for the good my main results are if players are sufficiently patient any positive average profit less than the maximum feasible level can be attained in a subgame perfect equilibrium in the subset of subgame perfect equilibria in which players use stationary strategies the seller cannot make sales at prices significantly greater than the lowest willingness to pay when period length goes to zero and the seller attains the maximum profit when commitment is feasible by charging the same static monopoly price in every period this paper analyzes a model of a dynamic monopolist who operates in a market in which there is a regular flow of new consumers the seller produces a durable good at constant unit cost each period a new cohort of consumers enters the market consumers wish to buy exactly one unit of the item but are willing to wait resales are not allowed each entering cohort is identical

information revelation in a market with pairwise meetings the paper presents a simple pairwise meetings model of trade the new feature is that agents have asymmetric information about the true state of the world the focus is on the transmission of the information through the process of trade the qualitative question is to what extent is the information revealed to uninformed agents through the trading process when the market is in some sense frictionless in particular does the decentralized process give rise to full revelation results as derived by the literature on rational expectations for centralized and competitive environments in the context of the model of this paper it turns out that the information is not fully revealed to uninformed agents even when the market is in some sense approximately frictionless

reputation and equilibrium selection in games with a patient player a single long run player plays a simultaneous move stage game against a sequence of opponents who play only once but observe all previous play let the stackelberg strategy be the pure strategy to which the long run player would most like to commit himself if there is positive prior probability that the long run player will always play the stackelberg strategy then his payoff in any nash equilibrium exceeds a bound that converges to the stackelberg payoff as his discount factor approaches one when the stage game is not simultaneous move this result must be modified to account for the possibility that distinct strategies of the long run player are observationally equivalent

disagreement in markets with matching and bargaining this paper develops an explanation of why bargainers often terminate negotiations in disagreement in spite of positive expected gains from continued negotiation the key to the analysis is a model which embeds bargaining activity within a market agents are continually faced with the choice between continuing to bargain with an existing partner or searching for a new partner bargainers may then terminate negotiations without an agreement in spite of positive expected gains from continued bargaining because seeking a new bargaining partner promises a higher return

entrants reputation and industry dynamics this article analyzes entry exit decisions in a market where reputation determines the price that firms may charge within a rational expectation model of competition in a nonatomic market under heterogeneous reputations the analysis focuses on the class of name switching reputational equilibria in which a firm discards its name if and only if its reputation falls below the entrants reputation the main technical result is the existence of a unique steady state equilibrium within this class in which the entrants reputation is endogenous the resulting industry dynamics is largely on agreement with the findings in the empirical literature

more dollars than sense refining our knowledge of development finance using aiddata summary in this introductory essay to the special issue we introduce a new dataset of foreign assistance aiddata that covers more bilateral and multilateral donors and more types of aid than existing datasets while also improving project level information about the purposes and activities funded by aid we utilize that data to provide a brief overview of important trends in foreign aid contributors to this special issue draw on aiddata as well as other sources to analyze aid transparency new donors not previously described or analyzed aid allocation and aid effectiveness our recurring theme in this introductory essay is that aiddata and these initial academic projects refine rather than revolutionize our understanding of aid the database has added significant numbers of new projects dollar amounts donors and details about those projects though there is much more yet to add we worry that aid debates have been driven by too little information and that many claims are based on limited or very poor evidence rectifying these problems will not be instantaneous refining knowledge takes a lot of time and hard work the common feature of the papers in this special issue is their careful attention to nuance and detail in spite of what some recent authors have claimed aid is neither a simple solution nor a sufficient cause of most problems in developing countries its motivations distribution and effects are complex and shifting capturing this complexity requires detailed data careful thought and sophisticated methods that allow scholars to make conditional causal and descriptive inferences 2011 elsevier ltd all rights reserved