commodity price shocks and civil conflict evidence from colombia how do income shocks aect armed con ict theory suggests two op posite eects if labor is used to appropriate resources violently higher wages may lower con ict by reducing labor supplied to appropriation this is the opportunity cost eect alternatively a rise in contestable income may increase violence by raising gains from appropriation this is the rapacity eect our paper exploits exogenous price shocks in inter national commodity markets and a rich dataset on civil war in colombia to assess how dierent income shocks aect con ict we examine changes in the price of agricultural goods which are labor intensive and natural resources which are capital intensive we focus on coee and oil the two largest exports we nd that a sharp fall in coee prices in the 1990s increased violence dierentially in regions growing more coee by lower ing wages and the opportunity cost of joining armed groups in contrast a rise in oil prices increased violence dierentially in the oil region by in creasing municipal revenue siphoned through rapacity this pattern holds in several other agricultural and natural resource sectors providing robust evidence that price shocks aect con ict in opposite directions depending on the factor intensity of the commodity

the welfare cost of lawlessness evidence from somali piracy in spite of general agreement that establishing the rule of law is central to properly functioning economies little is known about the cost of law and order breakdowns this paper studies a specific context of this by estimating the effect of somali piracy attacks on shipping costs using data on shipping contracts in the dry bulk market to estimate the effect of piracy we look at shipping routes whose shortest path exposes them to piracy and find that the increase in attacks in 2008 led to around an 8 to 12 increase in costs from this we calculate the welfare loss imposed by piracy we estimate that generating around 120 usd million of revenue for somali pirates led to a welfare loss in excess of 630 usd million making piracy an expensive way of making transfers

economic determinants of land invasions this study estimates the effect of economic conditions on redistributive conflict we examine land invasions in brazil using a panel data set with over 50 000 municipality year observations adverse eco nomic shocks instrumented by rainfall cause the rural poor to invade and occupy large landholdings this effect exhibits substantial heterogeneity by land inequality and land tenure systems but not by other observable variables in highly unequal municipalities negative income shocks cause twice as many land invasions as in municipalities with average land inequality cross sectional estimates using fine within region variation also suggest the importance of land inequality in explaining redistributive conflict i introduction c onflict over land is endemic to many rural econo mies in environments marked by a highly skewed distribution of property incomplete land and credit markets poorly or unevenly enforced property rights and weak political institutions agents often resort to extralegal means to improve their economic positions the poor frequently invade private properties and occupy them until either forcibly expelled or granted official titles land conflict which is prevalent in many countries such as brazil south africa uganda and venezuela may distort the allocation of resources in the agricultural sector away from productive uses and thereby contribute to the persistence of rural poverty how do economic conditions affect this redistrib utive conflict this paper explores this question using a rich municipal level data set of 5 299 land invasions from 1988 to 2004 in brazil we follow miguel satyanath and sergenti 2004 by using rainfall as a source of exogenous variation to study the relationship between income and conflict and we find that adverse economic shocks cause the rural poor to invade large landholdings this effect exhibits considerable het erogeneity by land inequality and land tenure systems in highly unequal municipalities negative income shocks cause twice as many land invasions as in municipalities with average land inequality the effect of income shocks is even stronger in highly polarized municipalities as measured by the degree of bimodality in the land distribution cross sectional estimates using fine within region variation also suggest the importance of land inequality in explaining redistributive conflict we also find that income shocks cause significantly more land invasions in municipalities with a greater proportion of land under fixed rent contracts by contrast we find no evidence of heterogeneity on a range of other political and socioeconomic variables including political competition sharecropping police expenditures and social welfare spending recent microeconometric studies have examined two

micro and macro elasticities in a life cycle model with taxes we build a life cycle model of labor supply that incorporates changes along both the intensive and extensive margin and use it to assess the consequences of changes in tax and transfer policies on equilibrium hours of work we find that changes in taxes have large aggregate effects on hours of work moreover we find that there is no inconsistency between this result and the empirical finding of small labor elasticities for prime age workers in our model micro and macro elasticities are effectively unrelated our model is also consistent with other cross country patterns

deductible contracts against fraudulent claims evidence from automobile insurance insurance fraud is now recognized as a significant resource allocation problem in many markets the object of this study is to verify how straight deductible contracts may affect the equilibrium level of falsification in automobile insurance this type of contract is observed in many markets even if it is not optimal under costly state falsification a higher deductible may create incentives to fraud or cheat particularly when the insured anticipates that the claim has a small probability of being audited to verify this proposition we estimate a loss equation for which one of the determinants is the amount of the deductible using a data set of claims filed for damages following an automobile accident with twenty insurance companies in quebec in 1992 because we have access only to reported losses a higher deductible also implies a lower probability of reporting small losses to isolate the fraud effect related to the presence of a deductible in the contract we jointly estimate a loss equation and a

the causes of hours constraints evidence from canada over half of workers are dissatisfied with the number of hours they work and of these the vast majority desire more rather than fewer hours using the canadian survey of work reduction we examine two potential explanations for hours constraints long term contracts due to worker moral hazard or specific capital and implicit contracts in which wages are insured but hours fluctuate our results contradict the moral hazard and insurance models and weakly support the specific capital model les causes des contraintes sur les heures de travail le cas canadien plus de la moitie des travailleurs ne sont pas satisfaits du nombre d heures qu ils travaillent et de ceux ci la grande majorite veut travailler plus et non pas moins d heures a l aide des donnees de l enquete canadienne sur la reduction des heures de travail les auteurs examinent deux sources potentielles d explication pour ce genre de phenomene les contrats a long terme attribuables au probl eme du capital humain specifique des travailleurs et au hasard moral et les contrats implicites par lesquels le niveau de salaire horaire est assure mais le nombre d heures travaillees fluctue les resultats presentes contredisent les modeles fondes sur le hasard moral et l assurance et supportent faiblement le modele de capital humain specifique surveys conducted in the united states consistently show that a substantial fraction of workers wish to work a different number of hours from those that they actually work of those who would like to change their hours the vast majority would prefer to work more hours shank 1986 in previous work kahn and lang 1992 we tested whether u s hours constraints could be explained by lifetime contract agency models in which the earnings profile is structured so as to deter worker cheating or

labor supply hours constraints and job mobility if hours can be freely varied within jobs the effect on hours of changes in preferences for those who do change jobs should be similar to the effect on hours for those who do not change jobs conversely if employers restrict hours choices then changes in preferences should affect hours more strongly when the job changes than when it does not change for a sample of married women we find that changes in many of the labor supply preference variables produce much larger effects on hours when the job changes

estimating the peace dividend the impact of violence on house prices in northern ireland this article exploits data on the pattern of violence across regions and over time to estimate the impact of the peace process in northern ireland on house prices after establishing a negative correlation between killings and house prices we estimate the parameters of a markov switching model with conflict and peace as latent states we use the model to estimate the size of the peace dividend as captured in house price changes jel d74 r23 r31 conflict in ireland has a long history even after the republic of ireland was created as an independent state in 1920 the status of the mainly protestant north remained contested from the late 1960s a violent conflict flared up which claimed around 3 500 lives only more than two decades later from 1993 onwards emerged a peace process which while initially fragile culminated in a cessation of violence and a return to devolved government by 2007 the conflict was a major source of social and economic dislocation but as peace took hold this has begun to be repaired this paper assesses the impact of peace by using variation in violence within northern ireland to study one important economic aspect of the peace process and the dividend that it brought to residents of northern ireland the impact on house prices houses are assets whose prices reflect the present and future expected attrac tiveness of living in an area even during the height of the conflict in northern ireland violence was not uniform for example belfast the capital city of the province of northern ireland was particularly hard hit looking for economic consequences of the peace process we would therefore expect benefits to be concentrated among areas where violence was most prevalent we exploit within region variability in violence and house prices over time having such variation is rare in studies of the economic consequences of conflict our specific measure of violence is conflict related deaths these have been well documented by sutton 1994 and the conflict archive on the

the political economy of deforestation in the tropics united states national aeronautics and space administration land cover and land use change and measures programs grant nng06gd95g

perceived ethicality of insurance claim fraud do higher deductibles lead to lower ethical standards insurance claim fraud costs insurance companies policymakers and taxpayers billions of dollars every year and has been described as the second largest white collar crime the most common insurance fraud activity and one that contributes a significant portion of dollar losses is the practice of padding claim amounts in the event of a loss one of the largest issues insurance companies face is that policyholders often do not perceive insurance claim padding as an unethical behavior however very little research has examined the factors that contribute to such perceptions considering how consumers often attempt to justify fraudulent behavior from a fairness perspective the present work examines how the amount of the deductible in an insurance claim situation can influence feelings of fairness and ethicality the results of an experimental study show that higher deductible amounts result in stronger perceptions that insurance claim padding is fair to the insurance company weaker perceptions that the behavior is unethical and higher proposed claim award amounts the study also shows however that the deductible amount effects are attenuated for consumers who display higher ethical standards as reflected by their scores on the consumer ethics scale implications are discussed with respect to the insurance industry deviant consumer behavior and general business ethics theory

labour demand and the source of adjustment costs to examine the importance of the two sources of costs of adjusting labor demand net costs of adjusting employment and gross costs of hiring and firing the author collects new sets of short monthly time series from a medium size hospital and three manufacturing plants models with quadratic costs and with lumpy costs are developed and yield lower bounds on the fraction of adjustment costs that are gross the estimates demonstrate that both types of costs affect dynamic labor demand but that gross adjustment costs especially and the turnover that generates them deserve much more attention copyright 1995 by royal economic society

insurance fraud and optimal claims settlement strategies abstract we examine the optimal claims settlement strategy for a liability insurer when claimants can permanently misrepresent their losses by engaging in costly claims falsification in this environment claims auditing is not a possible deterrent to fraud and the settlement strategy consists of an indemnification profile that relates the insurance payment to the claimed amount of loss the optimal indemnification profile is shown to involve systematic underpayment of claims at the margin as a means to deter loss exaggeration with the extent of underpayment limited by expected litigation costs and potential bad faith claims the key testable implication of the theory is that the extent of underpayment should be greater for classes of claims for which loss exaggeration is easier empirical analysis of insurance settlements for bodily injury liability in automobile accidents confirms this prediction this suggests that liability insurers optimally choose claims payment strategies to lessen a claimant s i

job search hours restrictions and desired hours of work a structural empirical job search model is presented that incorporates the labor supply decision of individuals the arrival of a job offer is modeled as a random draw from a wage hours offer distribution subjective information is used on desired working hours to identify optimal hours from offered hours policy simulations are performed to address several policy questions does a decrease in unemployment benefits lead to the acceptance of jobs with less preferred working hours how does a decrease in the length of the standard working week affect the job acceptance behavior of the unemployed

traders cops and robbers abstract we propose a simple model of trade outside the law preyed on by robbers and possibly protected by private cops we establish the conditions for trade collapse secure trade and insecure trade endogenous predation and enforcement can explain both puzzling failures of commonly observed state policies against illegal trade and puzzlingly large trade responses to liberalization in licit goods

insecurity and the pattern of trade an empirical investigation corruption and imperfect contract enforcement dramatically reduce international trade this paper estimates the reduction using a structural model of import demand in which insecurity acts as a hidden tax on trade we find that inadequate institutions constrain trade as much as tariffs do we also find that omission of indices of institutional quality biases the estimates of typical gravity models obscuring a negative relationship between per capita income and the share of total expenditure devoted to traded goods finally we argue that cross country variation in the effectiveness of institutions and the consequent variation in the prices of traded goods offer a simple explanation for the stylized fact that high income capital abundant countries trade disproportionately with each other

optimal auditing with scoring theory and application to insurance fraud this article makes a bridge between the theory of optimal auditing and the scoring methodology in an asymmetric information setting our application is meant for insurance claims fraud but it can be applied to many other activities that use the scoring approach fraud signals are classified based on the degree to which they reveal an increasing probability of fraud we show that the optimal auditing strategy takes the form of a red flags strategy which consists in referring claims to a special investigative unit siu when certain fraud indicators are observed the auditing policy acts as a deterrence device and we explain why it requires the commitment of the insurer and how it should affect the incentives of siu staffs the characterization of the optimal auditing strategy is robust to some degree of signal manipulation by defrauders as well as to the imperfect information of defrauders about the audit frequency the model is calibrated with data from a large european insurance company we show that it is possible to improve our results by separating different groups of insureds with different moral costs of fraud finally our results indicate how the deterrence effect of the audit scheme can be taken into account and how it affects the optimal auditing strategy

do you trust your insurer ambiguity about contract nonperformance and optimal insurance demand abstract we study optimal insurance demand for a risk and ambiguity averse consumer under ambiguity about contract nonperformance ambiguity aversion lowers optimal insurance demand and the consumer s degree of ambiguity aversion is negatively associated with the optimal level of coverage a more pessimistic belief and greater ambiguity may increase or decrease the optimal demand for insurance and we determine sufficient conditions for a negative effect we also discuss wealth effects and evaluate the robustness of our results by considering several alternative models of ambiguity aversion our findings show how ambiguity about contract nonperformance can undermine the functioning of insurance markets making it a concern for regulators caution is required though because demand reactions are only imperfectly informative about the welfare effects of ambiguity about contract nonperformance

covenants and collateral as incentives to monitor although monitoring borrowers is thought to be a major function of financial institutions the presence of other claimants reduces an institutional lender s incentives to do this thus loan contracts must be structured to enhance the lender s incentives to monitor covenants make a loan s effective maturity and the ability to collateralize makes a loan s effective priority contingent on monitoring by the lender thus both covenants and collateral can be motivated as contractual devices that increase a lender s incentive to monitor these results are consistent with a number of stylized facts about the use of covenants and collateral in institutional lending modern finance theory suggests that financial intermediaries such as commercial banks insurance companies and finance companies monitor and control their borrowers on behalf of other investors 1 this article investigates how the loans made by these institutions can be structured so as to best enhance the institutions role as delegated monitors covenants and collateral are common features of loans made by financial institutions but these features are somewhat difficult to justify consider loan covenants clauses in a loan contract that require the borrower to take or refrain from various actions berlin and mester 1992 magee and sridhar 1994 and park 1994 show that by giving institutions the right to renegotiate or call loans when covenants are violated covenants serve as tripwires that enhance the flexibility and efficiency of financial contracting also as documented in smith and warner 1979 control rights from covenants reduce borrower adverse selection or moral hazard nevertheless by allowing institutions to demand repayment based on any information contractible or not

incentives and the de soto effect this paper explores the consequences of improving property rights to facilitate the use of fixed assets as collateral popularly attributed to the influential policy advocate hernando de soto we use an equilibrium model of a credit market with moral hazard to characterize the theoretical effects and also develop a quantitative analysis using data from sri lanka we show that the effects are likely to be nonlinear and heterogeneous by wealth group they also depend on the extent of competition between lenders there can be significant increases in profits and reductions in interest rates when credit markets are competitive however since these are due to reductions in moral hazard that is increased effort the welfare gains tend to be modest when cost of effort is taken into account allowing for an extensive margin where borrowers gain access to the credit market can make these effects larger depending on the underlying wealth distribution

work hour mismatch and job mobility adjustment channels and resolution rates this paper analyses the role of job changes in overcoming work hour constraints and the work hour mismatches resulting from these constraints i e differences between actual and desired work hours building on previous findings that job change increases the flexibility of actual work hours the study addresses two as yet neglected questions in the context i how do changes in desired work hours in addition to changes in actual work hours contribute to the resolution of these mismatches ii does the increased flexibility help actually to resolve work hour mismatches we exploit information about the magnitude of the prevailing mismatch to improve both the credibility and interpretation of the results we find that job change increases the probability of resolving work hour mismatches but far less than expected with free choice of hours across jobs instead large fractions of workers either stay or switch into overemployment we thoroughly investigate the robustness and heterogeneity of our results

the simple economics of extortion evidence from trucking in aceh this paper tests whether the behavior of corrupt officials is consistent with standard industrial organization theory we designed a study in which surveyors accompanied indonesian truck drivers on 304 trips during which they observed over 6 000 illegal payments to police soldiers and weigh station attendants using plausibly exogenous changes in the number of checkpoints we show that market structure affects the level of illegal payments we further show that corrupt officials use complex pricing schemes including third degree price discrimination and a menu of two part tariffs our findings illustrate the importance of considering the market structure for bribes when designing anticorruption policy

property rights and deforestation in the brazilian amazon this paper focuses on the impact of property rights insecurity on deforestation in the brazilian legal amazon deforestation is considered as a risk management strategy property rights insecurity reduces the present value of forests and fosters forest conversion into agricultural and pasture lands moreover deforestation is the consequence of strategic interactions between landowners and squatters landowners clear the forest preventively in order to assert the productive use of land and to reduce the expropriation risk squatters invade land plots clear the forest and may afterwards gain official recognition with formal property titles a particular attention is paid to the measure of land property rights insecurity in the brazilian context it is assumed that property rights insecurity has a multidimensional character taken into account by the number of homicides related to land conflicts and expropriation procedures principal component analysis allows synthesising such information an econometric model of deforestation is estimated on a panel dataset on the 1988 2000 period and the nine states of the brazilian legal amazon the hypothesis that insecure land property rights contribute to higher rates of deforestation is not rejected when the simultaneity bias between insecure property rights and deforestation is addressed this result questions the modality of the brazilian land reform that considers forested areas as unproductive and thus open for expropriation procedures

job changes and hours changes understanding the path of labor supply adjustment we use british panel data to investigate single women s labor supply changes in response to three reforms that affected individuals work incentives we use these reforms to identify changes in labor supply there is evidence of small hours of work effects for two of such reforms a third reform in 1999 instead led to a significant increase in single mothers hours of work the mechanism by which the labor supply adjustments were made occurred largely through job changes rather than hours changes with the same employer this is little overall effect of the reforms on wages

is the behavior of hours worked consistent with implicit contract theory this paper examines the determinants of hours worked when employment relationships are influenced by risk sharing considerations the environment considered is an extension of the standard symmetric information risk sharing model that allows for the possibility of enforcement problems on the part of both the employer and the employee we show that this class of risk sharing models unambiguously predicts hours to be influenced by wages only through an income effect using data from the psed we find evidence in favor of this extended version of the risk sharing model

an arrgh chy the law and economics of pirate organization this article investigates the internal governance institutions of violent criminal enterprise by examining the law economics and organization of pirates to effectively organize their banditry pirates required mechanisms to prevent internal predation minimize crew conflict and maximize piratical profit pirates devised two institutions for this purpose first i analyze the system of piratical checks and balances crews used to constrain captain predation second i examine how pirates used democratic constitutions to minimize conflict and create piratical law and order pirate governance created sufficient order and cooperation to make pirates one of the most sophisticated and successful criminal organizations in history

the profits of power land rights and agricultural investment in ghana we examine the impact of ambiguous and contested land rights on investment and productivity in agriculture in akwapim ghana we show that individuals who hold powerful positions in a local political hierarchy have more secure tenure rights and that as a consequence they invest more in land fertility and have substantially higher output the intensity of investments on different plots cultivated by a given individual corresponds to that individual s security of tenure over those specific plots and in turn to the individual s position in the political hierarchy relevant to those specific plots

anarchy and its breakdown anarchy defined as a system in which participants can seize and defend resources without regulation from above is not chaos but rather a spontaneous order however anarchy is fragile and may dissolve either into formless amorphy or into a more organized system such as hierarchy under anarchy each contestant balances between productive exploitation of the current resource base and fighting to acquire or defend resources anarchy is sustainable only when there are strongly diminishing returns to fighting effort the decisiveness parameter is sufficiently low and incomes exceed the viability minimum these considerations explain many features of animal and human conflict

fixed costs and hours constraints hours constraints are typically identified by worker responses to questions asking whether they would prefer a job with more hours and more pay or fewer hours and less pay because jobs with different hours but the same rate of pay may be infeasible when there are fixed costs of employment or mandatory overtime premia the constraint in those cases may be illusory cross section estimates of reported hours constraints are consistent with this model implying that the overall level of hours constraints may exaggerate the extent to which the labor market is characterized by frictions and imperfections

growth and violence argument for a per capita measure of civil war the economics literature typically uses counts of casualties as a measure of conflict intensity despite the fact that the units of observation vary considerably in population size when analysing the impact of conflict on economic growth the use of counts relies on the assumption that a given number of casualties affects large and small populations in the same way using within and between country evidence this paper demonstrates that this standard assumption can be rejected a per capita model of conflict intensity that captures local effects of violence provides a more consistent empirical framework for both between country and within country studies

shrouded attributes consumer myopia and information suppression in competitive markets bayesian consumers infer that hidden add on prices e g the cost of ink for a printer are likely to be high prices if consumers are bayesian firms will not shroud information in equilibrium however shrouding may occur in an economy with some myopic or unaware consumers such shrouding creates an inefficiency which firms may have an incentive to eliminate by educating their competitors customers however if add ons have close substitutes a curse of debiasing arises and firms will not be able to profitably debias consumers by unshrouding add ons in equilibrium two kinds of exploitation coexist optimizing firms exploit myopic consumers through marketing schemes that shroud high priced add ons in turn sophisticated consumers exploit these marketing schemes it is not possible to profitably drive away the business of sophisticates it is also not possible to profitably lure either myopes or sophisticates to nonexploitative firms we show that informational shrouding flourishes even in highly competitive markets even in markets with costless advertising and even when the shrouding generates allocational inefficiencies

the effect of part time work on wages evidence from the social security rules this article identifies the part time wage effect using hours variation caused by the social security rules we show that work hours and wages drop sharply at ages 62 and 65 we argue that the hours decline causes the wage decline resulting in a 25 wage penalty for men who cut their work week from 40 to 20 hours however we find little evidence for such an effect among women we also show that models that fail to account for the joint determination of hours and wages will understate the labor supply response to a tax change by about 26

entitled to work urban property rights and labor supply in peru this brief summarizes the results of a gender impact evaluation study entitled entitled to work urban property rights and labor supply in peru new legal rights were issued in 1996 project teams providing titling service through 2003 in peru the study observed that between 1996 and 2003 the peruvian government issued property titles to over 1 2 million urban households the largest titling program targeted at urban squatters in the developing world this paper examines the labor market effects of increases in tenure security resulting from the program pre program squatters in program neighborhoods were significantly more likely to report improved tenure security by 60 percent similarly program participants were 18 8 percentage points less likely to report a high likelihood of eviction or invasion and 18 8 percentage points more likely to report that their dwelling was currently very secure from eviction or invasion the likelihood of working inside the home significantly falls by 11 6 percentage points for the average squatter family with two program periods

costly risk verification without commitment in competitive insurance markets abstract this paper analyzes the equilibrium of an insurance market where applicants for insurance have a duty of good faith when they reveal private information about their risk type insurers can at some cost verify the type of insureds who file a claim and they are allowed to retroactively void the insurance contract if it is established that the policyholder has misrepresented his risk when the contract was taken out however insurers cannot precommit to their risk verification strategy the paper analyzes the relationship between second best pareto optimality and the insurance market equilibrium in a game theoretic framework it characterizes the contracts offered at equilibrium the individuals contract choice as well as the conditions under which an equilibrium exists

fraudulent claims and nitpicky insurers insurance fraud is a major source of inefficiency in insurance markets a self justification of fraudulent behavior is that insurers are bad payers who start nitpicking if an opportunity arises even in circum stances where the good faith of policyholders is not in dispute we relate this nitpicking activity to the inability of insurers to commit to their auditing strategy reducing the indemnity payments acts as an incentive device for the insurer since auditing is profitable even if the claim is not fraudulent we show that optimal indemnity cuts are bounded above and that nitpicking remains optimal even if it induces adverse effects on policyholders moral standards

choice among wage hours packages an empirical investigation of male labor supply this article specifies and estimates an empirical model of male labor supply based on an implicit market model of wage hours determination we discuss how moving from a standard labor supply model to an implicit market model affects model specification and choice of estimation technique we find that average hourly earnings are not independent of hours worked and that ols estimates of the wage hours relationship are biased we also show that a labor supply model that assumes wages to be independent of hours worked produces a positively biased estimate of the effect of the wage on labor supply

constraints on the desired hours of work of british men this paper investigates constraints on desired hours of work using information on hours preferences from the british household panel survey for 1991 over a third of male manual workers would prefer to work fewer hours at the prevailing wage than they do and we estimate that on average desired hours per week are 4 3 lower than actual hours we hypothesise that job insecurity and scarcity of alternative job opportunities enable employers to set hours constraints above employee preferences and find that the minimum hours constraints set by firms are an increasing function of the unemployment rate an individual faces

testing intertemporal substitution implicit contracts and hours restriction models of the labor market using micro data we present new tests of three theories of the labor market intertemporal substitution hours restrictions and implicit contracts the intertemporal substitution test we implement is an exclusion test robust to many specification errors and we consistently reject this model we model hours restrictions as part of an endogenous switching model we compare the implicit probit equation to an unrestricted probit equation for unemployment and reject the hours restriction model for the implicit contracts model we estimate non separable within period labor supply and consumption equations we test a cross equation restriction of the model and cannot reject the implicit contracts model jel e30 j22 j60

the social efficiency of private decisions to enforce property rights costs must be incurred if an owner is to enforce private property rights effectively we show that in a perfectly competitive economy private decisions to enforce rights may result in either more or less enforcement than is socially efficient cases of multiple stable equilibria occur and an equilibrium may be locally but not globally efficient resources may not be employed in their socially most valuable uses and enforcement may be accompanied by inefficient investment in resource productivity

trafficking networks and the mexican drug war abstract drug trade related violence has escalated dramatically in mexico since 2007 and recent years have also witnessed large scale efforts to combat trafficking spearheaded by mexico s conservative pan party this study examines the direct and spillover effects of mexican policy toward the drug trade regression discontinuity estimates show that drug related violence increases substantially after close elections of pan mayors empirical evidence suggests that the violence reflects rival traffickers attempts to usurp territories after crackdowns have weakened incumbent criminals moreover the study uses a network model of trafficking routes to show that pan victories divert drug traffic increasing violence along alternative drug routes jel d72 d85 k42 o17 z13

time to build and fluctuations in bulk shipping abstract this paper explores the nature of fluctuations in world bulk shipping by quantifying the impact of time to build and demand uncertainty on investment and prices we examine the impact of both construction lags and their lengthening in periods of high investment activity by constructing a dynamic model of ship entry and exit a rich dataset of secondhand ship sales allows for a new estimation strategy resale prices provide direct information on value functions and allow their nonparametric estimation we find that moving from time varying to constant to no time to build reduces prices while significantly increasing both the level and volatility of investment jel g31 l11 l62 l92

optimal income taxation and job choice in this paper we study optimal income taxation when different job types exist for workers of different skills each job type has some feasible range of incomes from which workers choose by varying labor supply workers are more productive than others in the jobs that suit them best the model combines features of the classic optimal tax literature with labor variability along the intensive margin with the extensive margin approach where workers make discrete job choices and or participation decisions we find that first best maximin utility can be achieved in the second best and marginal tax rates below the top can be negative or zero

transportation costs and international trade in the second era of globalization while the precise causes of postwar trade growth are not well understood declines in transport costs top the lists of usual suspects however there is remarkably little systematic evidence documenting the decline this paper brings to bear an eclectic mix of data in order to provide a detailed accounting of the time series pattern of shipping costs the ad valorem impact of ocean shipping costs is not much lower today than in the 1950s with technological advances largely trumped by adverse cost shocks in contrast air shipping costs have dropped an order of magnitude and airborne trade has grown rapidly as a result as a result international trade has also experienced a significant rise in speed

h ours constraints and the wage hours locus surveys in the united states and canada reveal that approximately half of all workers would like to work a different number of hours per week if they could continue to receive their usual hourly wage of these about two thirds would like to work more hours and one third would like to work fewer hours kahn and lang 1991 shank 1986 despite the apparent prevalence of hours constraints the reasons why they exist are poorly understood in previous research we showed that lazear s 1981 agency model of the return to seniority is inconsistent with the data and that the specific capital model and insurance based implicit contract models cannot account for important regularities kahn and lang 1992 1995 in this paper we examine whether hours constraints can be explained by the existence of a hedonic wage hours locus we find that the actual wage hours locus is reasonably consistent with the wage hours locus predicted by observed hours constraints when the hedonic model is augmented by considerations of long term contracting we conclude that despite data and estimation shortcomings hedonic choices are an important reason for hours constraints to exist

optimal contracts when enforcement is a decision variable this paper analyzes choice theoretic costly enforcement in an intertemporal contracting model with a differentially informed investor and entrepreneur an intertemporal contract is modeled as a mechanism in which there is limited commitment to payment and enforcement decisions the goal of the analysis is to characterize the effect of choice theoretic costly enforcement on the structure of optimal contracts the paper shows that simple debt is the optimal contract when commitment is limited and costly enforcement is a decision variable theorem 1 in contrast stochastic contracts are optimal when agents can commit to the ex ante optimal decisions theorem 2 the paper also shows that the costly state verification model can be viewed as a reduced form of an enforcement model in which agents choose payments and strategies as part of a perfect bayesian nash equilibrium

labor supply preferences hours constraints and hours wage tradeoffs in a labor market with tied hours wage packages and wage dispersion for a particular type of job constrained workers may be willing to sacrifice wage gains for better hours when changing jobs likewise workers may accept jobs offering undesirable hours only if the associated wage gains are large we investigate this issue empirically by examining whether overemployment and underemployment on the initial and new job affects the relation between hours changes and wage changes for quitters our results generally support the view that an individual requires compensation to work in a job that given the individual s particular preferences offers unattractive hours

us food aid and civil conflict we study the effect of us food aid on conflict in recipient countries our analysis exploits time variation in food aid shipments due to changes in us wheat production and cross sectional variation in a country s tendency to receive any us food aid according to our estimates an increase in us food aid increases the incidence and duration of civil conflicts but has no robust effect on interstate conflicts or the onset of civil conflicts we also provide suggestive evidence that the effects are most pronounced in countries with a recent history of civil conflict jel d74 f35 o17 o19 q11 q18 we are unable to determine whether our aid helps or hinders one or more parties to the conflict it is clear that the losses particularly looted assets constitutes a serious barrier to the efficient and effective provision of assistance and can contribute to the war economy this raises a serious challenge for the humanitarian community can humanitarians be accused of fueling or prolonging the conflict in these two countries medecins sans frontieres amsterdam 1

the political resource curse this paper studies the effect of additional government revenues on political corruption and on the quality of politicians both with theory and data the theory is based on a political agency model with career concerns and endogenous entry of candidates the data refer to brazil where federal transfers to municipal governments change exogenously at given population thresholds allowing us to implement a regression discontinuity design the empirical evidence shows that larger transfers increase observed corruption and reduce the average education of candidates for mayor these and other more specific empirical results are in line with the predictions of the theory jel d72 d73 h77 o17 o18

take what you can property rights contestability and conflict weak property rights are strongly associated with underdevelopment low state capacity and civil conflict in economic models of conflict outbreaks of violence require a prize that is both valuable and contestable this paper exploits spatial and temporal variation in the availability of land with title that is contestable by private actors to explore the relationship between in secure property rights and civil conflict in the brazilian amazon the results suggest that resolving this contestability of title at the local level could eliminate substantively all local land related violence but might increase conflict in areas where title remained contestable

the effects of overtime pay regulation on worker compensation proponents claim that a statutory overtime premium by raising the relative cost of overtime may encourage firms to substitute employment for overtime hours the author argues that there will be no real effects if firms reduce straight time wages so as to offer the same package of weekly compensation and hours of work that was acceptable initially empirical analysis suggests that wage differentials do arise to mitigate the purely demand driven effects predicted by previous models but these differentials are not large enough to neutralize overtime pay regulation completely copyright 1991 by american economic association

diamonds are forever wars are not is conflict bad for private firms this paper studies the relationship between civil war and the value of firms in a poor resource abundant country using microeconomic data for angola we focus on diamond mining firms and conduct an event study on the sudden end of the conflict marked by the death of the rebel movement leader in 2002 we find that the stock market perceived this event as bad news rather than good news for companies holding concessions in angola as their abnormal returns declined by 4 percentage points the event had no effect on a control portfolio of otherwise similar diamond mining companies this finding is corroborated by other events and by the adoption of alternative methodologies we interpret our findings in light of conflict generated entry barriers government bargaining power and transparency in the licensing process jel d74 g32 o13 o17 q34

constraints on the choice of work hours agency versus specific capital lifetime contracts imply that at a given time wages and value of marginal product vmp will diverge the contract will specify hours as well as wages since firms will desire to prevent workers from working more when the wage is greater than vmp and from working less when the wage is less than vmp if hours are set efficiently workers will face binding hours constraints the agency model and the firm specific capital models make opposite predictions regarding the relation between work hours constraints and job tenure we test these predictions our results indicate that neither model explains the observed pattern of hours constraints

is honesty the best policy curtailing insurance fraud through optimal incentive contracts an incentive contracting approach is used to characterize optimal contracts when insured individuals possess private information about their losses and are able to misrepresent permanently their loss magnitudes by engaging in the falsification of claims we demonstrate that efficient agreements necessarily induce some falsification but that the extent of such claims inflation is mitigated partially by an indemnification schedule that overcompensates small losses while overpaying larger ones the differential costs of generating insurance claims through falsification provide an avenue by which the heterogencous insureds can credibly signal their underlying losses and are exploited in an optimal contract to implement loss contingent insurance payments

delegation as commitment the case of income tax audits in this article we study the value of delegating authority over income tax audit policy arising from the incompleteness of contracts consider a utilitarian government whose ability to commit is limited to aggregate dimensions of its audit policy as publicly verifiable information about detailed allocations of audit budgets is not available we show that the welfare level associated with the full commitment solution can be attained by delegating authority over audit policy to a manager the latter is offered a simple incentive scheme based only on the aggregate variables which are publicly observable in contrast if the government retains authority direct commitment to these same variables does not allow the full commitment welfare level to be achieved thus despite sharing a common informational basis delegation may perform better than centralized arrangements in the presence of incomplete contracts

hours restrictions and labor supply the authors estimate a labor supply model that permits hours restrictions of a simple but general form each individual chooses from among a finite set of jobs drawn at random f rom a market distribution each offering a fixed quantity of hours the polar cases of no constraints on hours worked and exogenous hours ar e nested within the general case the authors results are consistent with a substantial amount of rationing in the work hours of a sample of low income men most of whom are working less than they would like copyright 1993 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

estimation of a labour supply model with censoring due to unemployment and underemployment this study proposes and implements a method of labour supply estimation which is appropriate when the sample contains unemployed and underemployed workers the estimation method consists of excluding unemployed and underemployed workers from the sample and then using to avoid selection bias an extension of heckman s approach to the case where two correlated selection rules generate the sample hausman s specification test is then used to determine whether ignoring constrained workers has led to biases in traditional labour supply estimates and the empirical results suggest that previous estimates of several important parameters are biased since the biases go in the direction that would be predicted by the hypothesis that the unemployed and underemployed are constrained the results support this hypothesis

the effects of hours constraints on labor supply estimates almost all labor supply models are estimated under the assumption that workers are free to choose their hours however theory casual empiricism and survey data suggest that many workers are not free to vary the hours within a job consequently labor supply estimates based on actual hours of work may be biased using canadian data on desired hours of work the authors find that using actual hours causes labor supply estimates to be biased upwards copyright 1991 by mit press