intertemporal labor supply and human capital accumulation we solve and estimate a dynamic model that allows agents to optimally choose their labor hours and consumption and that allows for both human capital accumulation and savings estimation results and simulation exercises indicate that the intertemporal elasticity of substitution is much higher than the conventional estimates and the downward bias comes from the omission of the human capital accumulation effect the human capital accumulation effect renders the life cycle path of the shadow wage relatively flat even though wages increase with age hence a rather flat life cycle labor supply path can be reconciled with a high intertemporal elasticity of substitution

labor supply and the optimality of social security abstract traditional economic theory predicts that an unfunded public pension system can be justified on the basis of its ability to provide intergenerational transfers and also for its ability to provide partial insurance against mortality and labor income risks in this paper i demonstrate that the quantitative importance of these traditional roles depends on how the pension system distorts households labor supply decisions using a general equilibrium life cycle consumption model calibrated to the u s economy i show that these distortions can be large enough to erase much of the traditional welfare gains from social security i also find that this fact is robust within the range of labor supply elasticities usually encountered in the macroeconomic literature

induced innovation evolutionary theory and path dependence sources of technical change the i960s to the i98os were very productive of new theory and empirical insights into the sources of technical change in the i96os and i970s major attention focused on the implications of changes in demand and relative factor prices on the rate and direction of technical change in the late i 970s and early i980s attention shifted to evolutionary models inspired by a revival of interest in schumpeter s insights into the process of economic development since the early i98os these have been complemented by the development of historically grounded path dependent models of technical change each of these models has contributed substantial insight into the sources of technical change this paper was motivated by a perception that each of the three research agendas is approaching a dead end the three models induced evolutionary and path dependent represent elements of a more general theory that has not yet been invented ruttan 1996 a in a closing comment i suggest some steps toward the development of a more general theory of the sources of technical change

2018 klein lecture individual and aggregate labor supply in heterogeneous agent economies with intensive and extensive margins we study business cycle fluctuations in heterogeneous agent general equilibrium models featuring intensive and extensive margins of labor supply a nonlinear mapping from time devoted to work to labor services generates operative extensive and intensive margins our model captures the salient features of the empirical distribution of hours worked including how individuals transit within this distribution we study how various specifications influence labor supply responses to aggregate technology shocks and find that abstracting from intensive margin adjustment can have large effects on the volatility of aggregate hours even if fluctuations along the intensive margin are small

differential mortality and the progressivity of social security abstract there is a well established negative correlation between earnings and mortality risk using a calibrated general equilibrium macroeconomic model this paper examines how this correlation interacts with the welfare implications of social security s benefit earnings rule my primary findings suggest that the welfare ranking of alternative benefit earnings rules is somewhat sensitive to differential mortality due to their relatively high mortality risk households with unfavorable earnings histories heavily discount the expected utility from old age consumption and therefore do not put much weight on better work retirement consumption smoothing because of this reason social security s benefit earnings rule warrants less redistribution in the presence of differential mortality compared to when mortality risk is uncorrelated to earnings i find that this result continues to hold when household level labor supply distortions are ignored and also when an alternative maximin welfare criterion is considered but not when accidental bequests from the deceased are redistributed to the survivors

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

an empirical model of labor supply in a life cycle setting this paper formulates and estimates a structural intertemporal model of labor supply using theoretical characterizations derived from an economic model of lifetime behavior a two step empirical analysis yields estimates of intertemporal and uncompensated substitution effects which provide the information needed to predict the response of hours of work to life cycle wage growth and shifts in the lifetime wage path

structural transformation and the deterioration of european labor market outcomes this paper examines hours worked in continental europe and the united states from 1956 to 2003 the empirical work establishes two results first hours worked in europe decline by almost 45 percent compared to the united states over this period second this decline is almost entirely accounted for by the fact that europe develops a much smaller market service sector than the united states a simple model of time allocation is used to understand these patterns i find that relative increases in taxes and technological catch up can account for most of the differences between the european and american time allocations over this period

taxation and household labor supply we evaluate reforms to the u s tax system in a life cycle setup with heterogeneous married and single households and with an operative extensive margin in labor supply we restrict our model with observations on gender and skill premia labor force participation of married females across skill groups children and the structure of marital sorting we concentrate on two revenue neutral tax reforms a proportional income tax and a reform in which married individuals flle taxes separately separate flling our flndings indicate that tax reforms are accompanied by large increases in labor supply that difier across demographic groups with the bulk of the increase coming from married females under a proportional income tax reform married females account for more than 50 of the changes in hours across steady states while under separate flling reform married females account for all the change in hours

bounds on elasticities with optimization frictions a synthesis of micro and macro evidence on labor supply how can price elasticities be identified when agents face optimization frictions such as adjustment costs or inattention i derive bounds on structural price elasticities that are a function of the observed effect of a price change on demand the size of the price change and the degree of frictions the degree of frictions is measured by the utility losses agents tolerate to deviate from the frictionless optimum the bounds imply that frictions affect intensive margin elasticities much more than extensive margin elasticities i apply these bounds to the literature on labor supply the utility costs of ignoring the tax changes used to identify intensive margin labor supply elasticities are typically less than 1 of earnings as a result small frictions can explain the differences between micro and macro elasticities extensive and intensive margin elasticities and other disparate findings pooling estimates from existing studies i estimate a hicksian labor supply elasticity of 0 33 on the intensive margin and 0 25 on the extensive margin after accounting for frictions

aid allocation rules abstract this paper studies an aid allocation rule used by major development agencies and investigates optimal allocations when recipients are neoclassical economies undergoing transition dynamics when recipients face aid absorption constraints allocations that favor poorer recipients are not always optimal contrary to what is assumed in assessments of donor performance the most quantitatively significant factors that determine the optimal sensitivity to recipient characteristics are the generosity of the aid budget and the extent of absorption constraints in neoclassical recipients aid can only accelerate growth where there is already growth so the optimal rule places little weight on growth and optimality is largely a matter of balancing recipient need against absorption constraints

the estimation of a joint wage hours labor supply model in this paper the standard cross sectional static model of labor supply is modified to make the wage endogenous and a joint wage hours model is estimated the econometric technique addresses the non linearity of the budget constraint by approximating the constraint by a series of discrete points the results show that the budget constraint is indeed nonlinear that hours affect the wage quadratically that true wage elasticities are lower as a result and that the model fits the hours distribution much better than the standard tobit model

aid and donor trust in recipient country systems abstract the 2005 paris declaration on aid effectiveness sets targets for increased use by donors of recipient country systems for managing aid the target is premised on a view that country systems are strengthened when donors trust recipients to manage aid funds but undermined when donors manage aid through their own separate parallel systems this study provides an analytical framework for understanding donors decisions to trust or bypass country systems empirical tests are conducted using data from three oecd dac surveys designed to monitor progress toward paris declaration goals tests show that use of recipient country systems is positively related to 1 the donor s reputational stake in the country s development as proxied by the donor s share of aid provided to the recipient 2 the trustworthiness or quality of those systems as measured by cross country corruption indicators and 3 donors risk tolerance as proxied by public support for aid provision in donor countries findings are robust to corrections for potential sample selection omitted variables or endogeneity bias

sleep and the allocation of time using aggregated data for 12 countries a cross section of microeconomic data and a panel of households we demonstrate that increases in time in the labor market reduce sleep our theory of the demand for sleep differs from standard models of time use by assuming that sleep affects wages by affecting labor market productivity estimates of a system of demand equations demonstrate that higher wage rates reduce sleep time among men but increase their waking nonmarket time by an equal amount among women the wage effect on sleep is negative but very small

grants versus loans for development banks in recent years economists have increasingly debated whether multilateral development banks such as the world bank should switch from making subsidized loans to giving outright grants it is no small question the combined loans of the world bank group and brethren regional entities such as the asian and inter american development banks approach 300 billion their funds constitute a main channel through which rich country governments provide assistance to developing country governments in bulow and rogoff 1990 we first developed the case for a shift to outright grants we argued that under the status quo a vastly disproportionate share of aid goes to middle income countries via disguised interest subsidies rather than to the poorest countries we also argued that a shift to grants would protect donor banks from sometimes having to play a bad cop role when trying to collect net repayments rather than fully rolling over loans the meltzer commission international financial institution advisory commission 2000 report on government sponsored international lending institutions famously took a similar view supporters of the status quo often argue that development bank loans to middle income countries are in fact highly profitable and are essential for allowing institutions like the world bank to subsidize aid to poor countries we shall argue that the bank s profitability is an accounting artifice that greatly underestimates the risks of the bank s portfolio another argument for loans is that multilateral development banks have a superior enforcement technology that helps international debt markets to function more efficiently thus loans allow financially strapped governments including in middle income countries to borrow more than they could otherwise we will argue that this benefit too is an illusion in those cases when official lending does expand a developing country government s borrowing capacity it effectively enables the government to commit the country to repayment levels beyond that supported by domestic political consensus creating moral hazard for shortsighted rulers in theory better credit access to finance say public infrastructure projects can be highly beneficial in practice however the increased risk of debt crisis all too often outweighs any gain ordinary citizens might enjoy from the loans furthermore moral hazard on the part of lenders who may be able to induce rich countries into subsidizing the bailout of troubled middle income borrowers may mean that aggregate lending is excessive even if multilaterals merely displace equivalent private debt we do not argue for eliminating assistance to middle income countries on the contrary we would favor expanding aid in general albeit in far greater proportion to the world s poorest countries note that in principle any country with market access could use grant flows to help defray interest rate costs on loans if it so chose but development banks would never need to assume a bad cop role in enforcing debt

labor supply and government programs a cross country analysis abstract there are substantial cross country differences in labor supply late in the life cycle age 50 a theory of labor supply and retirement decisions is developed to quantitatively assess the role of social security disability insurance and taxation for understanding differences in labor supply late in the life cycle across european countries and the united states the findings support the view that government policies can go a long way towards accounting for the low labor supply late in the life cycle in the european countries relative to the united states with social security rules accounting for the bulk of these effects

cross country differences in unemployment fiscal policy unions and household preferences in general equilibrium we develop a five period overlapping generations model with individuals who differ by ability and with an imperfect labour market union wage setting for the individuals of lower ability the model explains human capital formation hours worked and unemployment within one coherent framework its predictions match the differences in the unemployment rate across 12 oecd countries remarkably well a shapley decomposition of these differences reveals an almost equal role for fiscal policy variables and union preferences as to fiscal policy differences in unemployment benefits play a much more important role than tax differences differences in households taste for leisure are unimportant

proliferation and fragmentation transactions costs and the value of aid abstract the problem of the proliferation of the number of aid donors and aid channels continues to worsen it is widely and plausibly believed that this significantly reduces the value of aid by increasing direct and indirect transactions costs we contribute to the existing literature by a categorising the apparent adverse effects of proliferation b producing a reliable and fair indicator of the relative degree to which the main bilateral donors proliferate or concentrate their aid c giving some explanation of why some donors proliferate more than others d constructing a reliable measure of the extent to which recipients suffer from the problem of fragmentation in the sources of their aid and e demonstrating that the worst proliferators among the aid donors are especially likely to be suppliers of aid to recipients suffering most from fragmentation there are significant implications for aid policy

what has been learned about labor supply in the past twenty years the main advance in the study of labor supply in the past 20 years has come in recognizing and interpreting the variety of different labor supply functions that coexist in the empirical literature a crucial theoretical distinction with important empirical payoff is that between labor supply choices at the extensive margin i e labor force participation and employment choices and choices at the intensive margin i e choices about hours of work or weeks of work for workers another important distinction is the one between a descriptive labor supply function and a structural supply function that can be the basis for out of sample policy investigations concerning responses to tax and welfare programs and evaluations of welfare losses a full understanding of the participation hours dichotomy leads to an appreciation of the importance of the problem of selection bias what is the wage to impute to a nonworking person these distinctions are a legacy of the research conducted on labor supply over the past 20 years many important empirical questions have been addressed i how strong are the effects of taxes welfare and transfer programs on labor supply ii how important is intertemporal substitution can life cycle labor supply models explain business cycle labor supply behavior iii has the consensus view of the 1960 s of high labor supply elasticities for married women and low labor supply elasticities for married men held up all of the empirical evidence assembled on labor supply must be called into question in the light of important research on the basic quality of the data conducted by analysts at the university of michigan i discuss this evidence in a concluding section except for my discussion of measurement issues i focus only on the major discoveries about which a general consensus has emerged

building or bypassing recipient country systems are donors defying the paris declaration the 2005 paris declaration on aid effectiveness sets targets for increased use by donors of recipient country systems for managing aid it also calls for donors to be more responsive to the quality of recipient country systems the optimal level of their use in terms of maximizing the development effectiveness of aid is believed to vary with their quality this study investigates the degree to which donors use of country systems is in fact positively related to their quality using indicators explicitly endorsed for this purpose by the paris declaration and covering the 2005 2010 period the results of these tests strongly confirm a positive and significant relationship and show it is robust to corrections for potential sample selection omitted variables or endogeneity bias the result holds even when estimates are informed only by variation over time within each donor recipient pair in use and quality of country systems moreover donor specific tests show that use of country systems varies positively with their quality for the vast majority of donors these findings contradict several other studies that claim there is no relation and imply that donors in this respect are failing to live up to their commitments under the paris declaration the author s interpretation of the available evidence on use of country systems is more favorable donors behavior over the measurement period is largely consistent with their commitments in this area in this respect at least donors appear to have modified their aid practices in ways that build rather than undermine administrative capacity and accountability in recipient country governments

long run equilibria with borrowing constraints and altruism this paper adapts a nonstochastic overlapping generations model to include liquidity constraints and intergenerational altruism existing work indicates the importance of both but often considers them separately this paper studies their interactions first it shows that they tend to conflict the model only admits stationary equilibria with dynastic wealth accumulation but no binding liquidity constraints or wity binding constraints but no dynastic accumulation second it examines the latter type of equilibrium closely if liquidity constraints bind quantitative examples imply that consequent utility losses may be small and that economywide wealth accumulation tends to be unrealistically low

time use and labor productivity the returns to sleep abstract we investigate how the largest use of time sleep affects productivity time use data from the united states allow us to test a model in which sleep improves productivity consistent with t

household search and the aggregate labor market we develop a theoretical model with labour market frictions incomplete financial markets and with households which have two members households face unemployment risks but their members adjust their labour supplies to insure against unemployment we use the model to explain the cyclical properties of aggregate employment and participation as in the u s data the model predicts that the participation rate the fraction of individuals that want jobs is not strongly correlated with aggregate economic activity this property is in sharp contrast to the strongly procyclical participation predicted by both neoclassical models and models with search frictions when we assume bachelor households or households with infinitely many members complete markets in the two member household model and in the data primary earners are always in the labour force secondary earners have a mildly countercyclical participation rate and a mildly procyclical employment rate their behaviour insures the household against unemployment risks

heterogeneity and aggregation implications for labor market fluctuations we demonstrate that aggregate employment and consumption can increase without a corresponding movement in productivity in a model with heterogeneous agents where the only aggregate disturbance is a productivity shock the interaction between incomplete capital markets and indivisible labor results in a low employment productivity correlation and creates a time varying wedge between the marginal rate of substitution for commodity consumption and hours and productivity our results caution against viewing the measured wedge as an inefficiency due to a failure of labor market clearing or as a fundamental driving force behind business cycles jel d31 e32 j22 j24 j31

random earnings differences lifetime liquidity constraints and altruistic intergenerational transfers abstract this paper develops a model of private savings behavior in which households care about their descendants cannot have negative net worth and have lifetime earnings depending on random draws from an exogenous distribution of abilities the elements interact very lucky parents are likely to leave large estates constrained children are unusually likely to receive intergenerational transfers the paper proves the existence of a stationary cross sectional distribution of wealth endogenously determines where liquidity constraints will bind and shows that the long term interest rate must be such that ricardian neutrality fails its last section generates several illustrative numerical simulations

aid supplies over time addressing heterogeneity trends and dynamics summary what determines how much foreign aid donors provide existing answers to this question point to a complex range of influences however the tasks of distinguishing between long and short run factors as well as differences between donors have not been adequately addressed taking advantage of data spanning nearly 50 years this paper uses panel cointegration techniques to consider these issues the analysis provides clear evidence for heterogeneity both between donors and over time bandwagon effects and a growing influence of security considerations in aid provision domestic macroeconomic shocks have a moderate but delayed effect on aid disbursements

effective tax rates in macroeconomics cross country estimates of tax rates on factor incomes and consumption abstract this paper proposes a method for computing tax rates using national accounts and revenue statistics using this method we construct time series of tax rates for large industrial countries the method identifies the revenue raised by different taxes at the general government level and defines aggregate measures of the corresponding tax bases this method yields estimates of effective tax rates on factor incomes and consumption consistent with the tax distortions faced by a representative agent in a general equilibrium framework these tax rates compare favorably with existing estimates of marginal tax rates and highlight important international differences in tax policy

the demand for youth explaining age differences in the volatility of hours over the business cycle young workers experience much greater volatility of hours worked than prime aged workers this can arise from age differences in labor supply or labor demand characteristics to distinguish between these we document that for young workers both the cyclical volatilities of hours and wages are greater than those of the prime aged we argue that a general class of models featuring only age specific labor supply differences cannot reconcile these facts we then show that a simple model featuring labor demand differences can

globalizing carbon lock in this paper extends the arguments surrounding carbon lock in elaborated in unruh energy policy 28 2000 817 30 2002 317 to countries currently undergoing industrialization it argues that for numerous reasons industrializing countries are unlikely to leapfrog carbon intensive energy development on the contrary carbon lock in may be globalizing and could further constrain climate change mitigation options it is then argued that many policy recommendations ignore carbon lock in possibly limiting their potential for successful implementation the paper then discusses four policy approaches that appear to have advantages given lock in conditions it is recognized however that relative ease of implementation does not necessarily equate with superiority instead it is merely a path dependent outcome of past development decisions pursuing policies on the basis of relative implementation ease may help address the issue of climate change but could also result in sub optimal outcomes along other dimensions of sustainable development

do performance measures of donors aid allocation underperform indices of donor performance abound their recent popularity has occurred within the context of pessimism over aid s impact and optimism over the effect of changes in donor behaviour rankings of donor allocative performance aim to change donor behaviour either through direct pressure on governments or indirectly through public engagement the indices themselves rely on descriptive measures and typically claim methodological superiority over positive alternatives due to their simplicity however there are two problems first measures do not seem robust to simple variations in methodology second correlation amongst competing indices is low leading to a host of contradictory judgements this offers neither clear technical guidance nor consistent political pressure the advantages and disadvantages of the approach are discussed building upon the more general critique of aggregate indices i suggest a graphical solution that embraces the advantages of the descriptive approach including ease of public communication while avoiding some of its major weaknesses which typically stem from aggregation

individual and aggregate labor supply in heterogeneous agent economies with intensive and extensive margins we develop a heterogeneous agent general equilibrium model that incorporates both intensive and extensive margins of labor supply a nonconvexity in the mapping between time devoted to work and labor services distinguishes between extensive and intensive margins we consider calibrated versions of this model that dier in the value of a key preference parameter for labor supply and the extent of heterogeneity the model is able to capture the salient features of the empirical distribution of hours worked including how individuals transit within this distribution we then study how the various specications inuence labor supply responses to aggregate technology shocks we nd that abstracting from intensive margin adjustment has large eects on the volatility of aggregate hours even if intensive margin uctuates relatively little

aid selectivity according to augmented criteria a dominant trend in the literature maintains that donor assistance should be targeted to poor countries with sound institutions and policies in this context donor selectivity refers to what extent aid is allocated according to the principles of this canonical model this paper shows that it is legitimate for donors to simultaneously use other selectivity criteria corresponding either to expected factors of aid effectiveness or to handicaps to development it is notably argued that vulnerability to exogenous shocks and low level of human capital should be considered as selectivity criteria taking these other criteria into account dramatically changes the assessment of donor selectivity

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

the impact of immigration why do studies reach such different results we classify the empirical literature on the wage impact of immigration into three groups where studies in the first two groups estimate different relative effects and studies in the third group estimate the total effect of immigration on wages we interpret the estimates obtained from the different approaches through the lens of the canonical model to demonstrate that they are not comparable we then relax two key assumptions in this literature allowing for inelastic and heterogeneous labor supply elasticities of natives and the downgrading of immigrants downgrading occurs when the position of immigrants in the labor market is systematically lower than the position of natives with the same observed education and experience levels downgrading means that immigrants receive lower returns to the same measured skills than natives when these skills are acquired in their country of origin we show that heterogeneous labor supply elasticities if ignored may complicate the interpretation of wage estimates and particularly the interpretation of relative wage effects moreover downgrading may lead to biased estimates in those approaches that estimate relative effects of immigration but not in approaches that estimate total effects we conclude that empirical models that estimate total effects not only answer important policy questions but are also more robust to alternative assumptions than models that estimate relative effects

aid policies and growth the authors of this paper use a new database on foreign aid to examine the relationships among foreign aid economic policies and growth of per capita gdp in panel growth regressions for 56 developing countries and 6 four year periods 1970 93 they find that the policies that have a great effect on growth are those related to fiscal surplus inflation and trade openness they construct an index for those three policies and have that index interact with foreign aid they have instruments for both aid and aid interacting with policies they find that aid has a positive impact on growth in developing countries with good fiscal monetary and trade policies in the presence of poor policies aid has no positive effect on growth this result is robust in a variety of specifications which include or exclude middle income countries include or exclude outliers and treat policies as exogenous or endogenous they examine the determinants of policy and find no evidence that aid has systematically affected policies either for good or for ill they estimate an aid allocation equation and show that any tendency for aid to reward good policies has been overwhelmed by donors pursuit of their own strategic interests in a counterfactual they reallocate aid reduce the role of donor interests and increasing the importance of policy such a reallocation would have a large positive effect on developing countries growth rates

a life cycle model of health and retirement the case of swedish pension reform abstract sweden is one of the few western economies to have undertaken a large pension reform in recent years this was done with great expectations but little formal analysis in this paper we develop a life cycle labor supply model to quantify the predicted labor supply implications of this reform in our framework individuals choose when to stop working and given eligibility criteria when if to apply for disability and pension benefits agents are heterogeneous in skills and receive exogenous shocks to health throughout their life we find that the new pension system creates large incentives for the continued employment of older workers this is promising news for countries grappling with pension reform and indicates that there are significant lessons to be learned from the swedish case

time use during the great recession using data from the american time use survey between 2003 and 2010 we document that home production absorbs roughly 30 percent of foregone market work hours at business cycle frequencies leisure absorbs roughly 50 percent of foregone market work hours with sleeping and television watching accounting for most of this increase we document significant increases in time spent on shopping child care education and health job search absorbs between 2 and 6 percent of foregone market work hours we discuss the implications of our results for business cycle models with home production and non separable preferences jel codes d13 e32 j22

impactos das distorcoes tributarias sobre a determinacao da oferta de trabalho usando um modelo de crescimento neoclassico prescott 2004 e ohanian et alii 2008 explicam com sucesso as diferencas de horas trabalhadas entre paises da ocde aplicamos este mesmo modelo para o caso brasileiro entre 1988 e 1998 nossa principal conclusao e que esta metodologia falha em explicar a experiencia brasileira o modelo preve como consequencia do aumento de impostos verificado no periodo uma queda substancial no numero de horas trabalhadas entretanto os dados mostram apenas uma leve queda utilizamos ainda especificacoes alternativas para a preferencia do agente representativo as quais tornam a oferta de trabalho menos sensivel a impostos entretanto o ajuste aos dados e satisfatorio apenas para par metros bastante distantes daqueles utilizados pela literatura internacional sugerimos que a presenca significativa de um setor informal pode explicar a especificidade brasileira

determining the motives for a positive optimal tax on capital previous literature demonstrates that in a computational life cycle model the optimal tax on capital is positive and large given the computational complexities of these overlapping generations models it is helpful to to determine the relative importance of the economic factors driving this result i highlight the impact of changing two common assumptions in a benchmark model that generates a large optimal tax on capital similar to the model in conesa et al 2009 first the utility function is altered such that it implies an agent s frisch labor supply elasticity is constant as opposed to increasing over his lifetime second the government is allowed to tax accidental bequests at a separate rate from ordinary capital income the main nding of this paper is that these two changes cause the optimal tax on capital to drop by almost half furthermore i nd that the welfare costs of adopting the high optimal tax on capital from the benchmark model in the model with the altered assumptions which calls for a lower tax on capital are equivalent to 0 35 percent of total lifetime consumption quantifying the impact of these assumptions in the benchmark model is important because the rst has limited empirical evidence and the second although included for tractability confounds a motive for taxing capital with a motive for taxing accidental bequests jel e62 h21

biodiversity conservation in a dynamic world may lead to inefficiencies due to lock in effects and path dependence abstract although biodiversity is generally diminishing in some areas its conservation is expanding however the exact path of this expansion is uncertain this can lead to problems of path dependence and lock in effects path dependence describes situations where history strongly influences present decisions and lock in effects refer to situations where an earlier decision provides strong incentives to follow a particular path even if more efficient alternatives are available later on we develop a conceptual ecological economic model to investigate which ecological and economic parameters favour the appearance of efficiency losses in biodiversity conservation due to path dependence and lock in effects in a dynamic two period two region model generally we find that efficiency losses occur if there are signals that guide the first period budget into a region that later turns out to be suboptimal if both time periods had been considered right from the beginning to illustrate the conservation relevance of our findings we present potential efficiency losses through path dependence in the hypothetical case of applying offsets to conserving the endangered maculinea teleius butterfly near the city of landau in germany

the political economy of foreign aid a model of the market for a public good what determines the type and quantity of overseas aid given by individual donor countries answers to this question in the existing literature are polarized into two groups one of them offers a theoretical treatment based on the theory of public goods which is not consistent with the available data and the other offers empirical correlations without any explanatory theory the first group for example pincus and olson and zeckhauser treats aid like defense as an international public good small countries on this approach are free riders spending relatively little themselves while deriving benefits from the expenditures of larger countries but this approach is not consistent with even a casual scrutiny of the oecd aid community in which broadly speaking the smallest countries are the most generous donors 2 the second group for example hoadley and beenstockdiscover correlations between a country s ratio of aid to gnp and certain independent variables which may be expected to influence it e g that country s gnp its dependence on foreign trade its government s position in the ideological spectrum and the state of the domestic economy 3 however these findings are not fitted into any theoretical framework so that it is difficult to work out what they really mean 4 the approach of this paper is to treat foreign aid as a public good for which there is a market albeit a highly imperfect one because the consumers donor country taxpayers are ignorant about the very nature let alone the price of the commodity they are buying on this view factors on the demand side i e taxpayers response to their country s aid program will help to determine the quantity of aid disbursed as well as factors on the supply side such as the donor government s desire to obtain strategic or trading benefits from aid this view

barriers to political analysis in aid bureaucracies from principle to practice in dfid and the world bank summary politics has become a central concern in development discourse and yet the use of political analysis as a means for greater aid effectiveness remains limited and contested within development agencies this article uses qualitative data from two governance leaders the united kingdom department for international development and the world bank to analyze the administrative hurdles facing the institutionalization of political analysis in aid bureaucracies we find that programing management and training practices across headquarters and country offices remain largely untouched by a political analysis agenda which suffers from its identification with a small cross national network of governance professionals

amenity driven price effects and conservation reserve site selection a dynamic linear integer programming approach most conservation reserve design models presented in the literature are static and ignore the dynamic economic aspects of site selection typically conservation programs operate under time related e g annual budgets and purchase land over time in a sequential manner the uncertainty of land development has been incorporated in a few dynamic reserve selection formulations using stochastic dynamic programming however the existing formulations do not explicitly deal with inter temporal price and location linkages we address this issue here and present a two period linear integer programming model for conservation reserve design that incorporates amenity driven price feedback effects inherent in the reserve development problem in addition the model includes spatial and ecological criteria we then use this model to answer the question how suboptimal is ignoring amenity driven price effects in reserve design models we apply the model to artificially generated data sets and compare the results with the results of an iterated static model that considers only one period at a time we find that the dynamic model with price feedback effects selects sites at a lower per site cost the policy implication of this finding is that conservation programs should avoid purchasing land in the same neighborhood over multiple time periods

global samaritans donor election cycles and the allocation of humanitarian aid abstract this paper finds a large causal donor election cycle effect in humanitarian aid allocations on average humanitarian aid increases by 19 in the year before elections our identification strategy consists of focusing on donors with fixed election dates making elections clearly exogenous furthermore we find large interaction effects with natural and human disasters this evidence is consistent with our theory that incumbent governments responding to humanitarian disasters can increase voter support for their party and insure against the political fall out of not being seen as representatives of a country with global interests and influence however it is important to stress that despite our findings human and natural disasters explain a substantially larger share of the overall variation in humanitarian aid observed in the data

policy evaluation via composite indexes qualitative lessons from international transparency policy indexes summary international transparency policy indexes itpis help determine billions in investment and aid influence authoritative scholarship and shape policy choices are itpis valid yardsticks of transparency or do they encourage dissimulation most scholarship on index based evaluations focuses on concept indexes e g governance from quantitative approaches this paper presents qualitative insights about itpis in specific and policy indexes in general analyzing three measurement related pitfalls and proposing countermeasures most significantly it shows how indexes presuppose substitutability while policies contain nonsubstitutable necessary policy provisions this dilemma of ontological compatibility means that policies can rank favorably on indexes notwithstanding the absence of lynchpin policy provisions

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

donor competition for aid impact and aid fragmentation we show that donors that maximize relative aid impact spread their budgets across many recipient countries in a unique nash equilibrium this aid fragmentation result is robust to the introduction of fixed costs even if they are improbably large in equilibrium smaller donors have less fragmented aid and behave better from an efficiency viewpoint we present evidence that our theoretical results are in line with cross country correlations our analysis has important policy implications first short of ending donors maximization of relative aid impact agreements to better coordinate aid allocations are not implementable second since policies to increase donor competition in terms of aid effectiveness risk reinforcing relativeness they may well backfire as any such reinforcement increases aid fragmentation

effects of permanent and transitory tax changes in a life cycle labor supply model with human capital i examine effects of labor income taxation in life cycle models with human capital accumulation in this case the opportunity cost of time equals the wage plus returns to work experience this has several interesting consequences first the data appear consistent with larger labor supply elasticities than prior work suggests second contrary to conventional wisdom permanent tax changes can have larger effects on current labor supply than temporary changes third human capital dampens responses of young workers to transitory tax changes fourth labor supply elasticities increase with age fifth human capital amplifies the effect of permanent tax changes in the long run

anticipated and unanticipated wage changes wage risk and intertemporal labor supply in this article i estimate how labor supply responds to anticipated wage growth unanticipated wage growth and wage risk using the 1989 93 panel section of the bank of italy survey of households income and wealth shiw which collects individual expectations of future wages the use of subjective expectations has several advantages first they provide information on the evolution and riskiness of future wages that the econometrician may never hope to observe moreover this avoids the need for specifying instruments for the growth rate of wages finally forecast errors can be directly controlled for thus avoiding inconsistency in short panels

taxes and time allocation evidence from single women and men the classic model of becker 1965 suggests that labor supply decisions should be analyzed within the broader context of time allocation and market good consumption choices but most empirical work on policy has focused exclusively on measuring impacts on market work this paper examines how income taxes affect time allocation during the entire day and how these time allocation decisions interact with expenditure patterns using the panel study of income dynamics from 1975 to 2004 we analyze the response of single women s housework labor supply and other time to variation in tax and transfer schedules across income levels number of children states and time we find that when the economic reward to participating in the labor force increases market work increases and housework decreases with the decrease in housework accounting for approximately two thirds of the increase in market work analysis of repeated cross sections of time diary data from 1975 to 2004 shows that home production decreases substantially when market hours of work increase in response to policy changes data on expenditures from the consumer expenditure survey from 1980 to 2003 show some evidence that expenditures on market goods likely to substitute for housework increase in response to a greater incentive to join the labor force the baseline estimates imply that the elasticity of substitution between consumption of home and market goods is 2 61 the results are consistent with the becker model meanwhile single men show little response to changes in tax policy and we are able to rule out an elasticity of substitution between home and market goods for this group of more than 1 52

biological conservation in dynamic agricultural landscapes effectiveness of public policies and trade offs with agricultural production article i nfo land use change and land management intensification are major drivers of biodiversity loss especially in agricultural landscapes that cover a large and increasing share of the world s surface incentive based agri environmental policies are designed to influence farmers land use decisions in order to mitigate environmental degradation this paper evaluates the effectiveness of agri environmental schemes for biological conservation in a dynamic agricultural landscape under economic uncertainty we develop a dynamic ecological economic model of agricultural land use and spatially explicit population dynamics we then relate policies subsidies to grassland taxation of agricultural intensity to the ecological outcome probability of persistence of a species of interest we also analyze the associated trade offs between agricultural production in value and biological conservation in probability of persistence at the landscape scale

bilateral donors and the age of the national interest what prospects for challenge by development agencies summary foreign aid agencies represent and champion global development priorities within a donor nation increasingly however these agencies sit within donor governments that are strongly committed to upholding the national interest through their development commitments this paper is concerned with how bilateral aid agencies manage this tension and how they might continue to serve the altruistic aims of development the main research question asks if autonomy or a combination of autonomies can improve a development agency s ability to defend the humanitarian imperative of development against normative pressures privileging the national interest by drawing on theories of autonomy within public management literatures it is possible to identify points of leverage for development agencies where spaces for autonomous preferences and actions remain as well as sources of limitation where such opportunities are considerably reduced six types of autonomy are examined across three nations widely perceived as strong performers as donors norway the uk and sweden the paper suggests that while structural autonomy is critical for preserving humanitarian motivations there are also unexplored opportunities within other autonomous spheres a multi dimensional examination of autonomy highlights the varying capacity that development agencies have to resist pressures to strongly nationalize the global development project

optimal fiscal policy and different degrees of access to international capital markets abstract empirically the cyclical pattern of fiscal policy differs between developed and developing countries with in particular much greater pro cyclicality and volatility of public investment in developing countries in this paper i provide a theoretical explanation for the observed differences by analyzing optimal fiscal policy under different degrees of access to world capital markets if the supply of foreign capital is elastic as in a developed country then it is optimal to adjust to an adverse external shock by borrowing from abroad to finance public expenditure and cutting taxes to smooth private consumption if the supply of foreign capital is inelastic however as in a developing country the optimal adjustment policy is to reduce public investment by much more than public consumption and to raise consumption taxes

darlings and orphans interactions across donors in international aid we examine how bilateral aid flows of an individual donor to a recipient depend on aid flows from all other bilateral and multilateral donors to that recipient we thereby assess to what extent issues including donor coordination free riding selectivity specialization and common donor interests drive bilateral aid allocations we find that others bilateral flows lead to a significant increase in aid flows from a particular donor but primarily within a given year the effects are particularly pronounced for large donors and so called darling recipients overall the results suggest that herding is a dominant feature of aid inter relationships this article is protected by copyright all rights reserved

aid tying and donor fragmentation this study tests two opposing hypotheses about the impact of aid fragmentation on the practice of aid tying in one when a small number of donors dominate the aid market in a country they may exploit their monopoly power by tying more aid to purchases from contractors based in their own countries alternatively when donors have a larger share of the aid market they may have stronger incentives to maximize the development impact of their aid by tying less of it empirical tests strongly and consistently support the latter hypothesis the key finding that higher donor aid shares are associated with less aid tying is robust to recipient controls donor fixed effects and instrumental variables estimation when recipient countries are grouped by their scores on corruption perception indexes higher shares of aid are significantly related to lower aid tying only in the less corrupt sub sample this finding is consistent with the argument that aid tying can be an efficient response by donors when losses from corruption may rival or exceed losses from tying aid when aid tying is more costly as proxied by donor country size and income it is less prevalent aid tying is lower in the least developed countries consistent with the oecd development assistance committee s recommendation to its members

the effects of health wealth and wages on labour supply and retirement behaviour this paper estimates a life cycle model of labour supply retirement and savings behaviour in which future health status and wages are uncertain individuals face a fixed cost of work and cannot borrow against future labour pension or social security income the method of simulated moments is used to match the life cycle profiles of labour force participation hours worked and assets that are estimated from the data to those that are generated by the model the model establishes that the tax structure of the social security system and pensions are key determinants of the high observed job exit rates at ages 62 and 65 removing the tax wedge embedded in the social security earnings test for individuals aged 65 and older would delay job exit by almost one year by contrast social security benefit levels health and borrowing constraints are less important determinants of job exit at older ages for example reducing social security benefits by 20 would cause workers to delay exit from the labour force by only three months

a model of sleep leisure and work over the business cycle abstract this paper uses a single sector dynamic stochastic general equilibrium dsge model to analyze time use patterns over the business cycle using data from the american time use survey we solve and simulate a model of a utility maximizing consumer subject to a penalty function based on a biological model for sleep we find that sleep is countercyclical with the business cycle sleep increases as economic activity declines we also show that our model provides a reasonable estimate of observed sleep behavior over the period from 2003 through 2016 our results suggest that separating sleep from other non work activities is a useful and productive exercise for these types of models

prosperity and depression prosperity and depression are relative concepts today both france and japan are depressed relative to the united states equivalently the united states is prosperous relative to these countries i say these countries are depressed relative to the united states because their output per working age person is 30 percent less than the u s level an interesting and important policy question is why are these countries depressed the answers for these two countries turn out to be very different the united states is prosperous relative to france because the u s intratemporal tax wedge that distorts the trade off between consumption and leisure is much smaller than the french wedge i will show that if france modified its intratemporal tax wedge so that its value was the same as the u s value french welfare in consumption equivalents would increase by 19 percent consumption would have to increase by 19 percent now and in all future periods to achieve as large a welfare gain as that resulting from this tax reform the united states is prosperous relative to japan because production efficiency is higher in the united states in the united states total factor productivity is approximately 20 percent higher than in japan if japan suddenly became as efficient in production as the united states its welfare gain in consumption equivalents would be 39 percent equally interesting and important are big changes over time in relative output per working age person across countries why are new zealand s and switzerland s economies depressed by over 30 percent relative to their 1970 trend corrected levels both of these countries have small populations but depressions are not restricted to small countries japan with its 125 million people is now depressed by 20 percent relative to its 1991 trend corrected level on the prosperity side why are ireland and south korea so prosperous now relative to their 1970 trend corrected levels this lecture is concerned primarily with big international differences among relatively rich industrial countries and changes in these differences over time the countries that receive primary attention all have market economies and healthy well educated populations in the countries considered the variations in aggregate output per working age person are large and reasonably good measures of the factor inputs are available this permits in many cases the identification of the change in policy or the difference in policy that gave rise to prosperity or depression this is in contrast to business cycle theory which provides little guidance to policy except for the important policy implication that a stabilization effort will have either no effect or a perverse effect the output variations studied and analyzed in this lecture are big an order of magnitude larger than the much studied business cycle fluctuations the variations studied however are an order of magnitude smaller than the muchstudied differences between the richest and poorest countries surprisingly only recently have depressions been systematically studied from the perspective of growth theory which is the theory used university of minnesota and federal reserve bank of minneapolis i thank my colleagues at the university of minnesota and the federal reserve bank of minneapolis for helpful discussions and comments in particular i thank tim kehoe ellen mcgrattan and nancy stokey for their help i also thank martin weale and franck portier for providing some british and french tax information used in this lecture thanks also go to sami alpanda and james macgee for research assistance and helpful discussions this lecture draws heavily on collaborative research with fumio hayashi i thank the economic and social research institute cabinet office government of japan and the u s national science foundation for financial support the views expressed herein are those of the author and not necessarily those of the federal reserve bank of minneapolis or the federal reserve system

adjustment costs firm responses and micro vs macro labor supply elasticities evidence from danish tax records we show that the effects of taxes on labor supply are shaped by interactions between adjustment costs for workers and hours constraints set by firms we develop a model in which firms post job offers characterized by an hours requirement and workers pay search costs to find jobs we present evidence supporting three predictions of this model by analyzing bunching at kinks using danish tax records first larger kinks generate larger taxable income elasticities second kinks that apply to a larger group of workers generate larger elasticities third the distribution of job offers is tailored to match workers aggregate tax preferences in equilibrium our results suggest that macro elasticities may be substantially larger than the estimates obtained using standard microeconometric methods

on the delegation of aid implementation to multilateral agencies some multilateral agencies implement aid projects in a broad range of sectors with aid disbursements showing a strong overlap with those of bilateral donors the question then arises of why do bilateral donors delegate sizable shares of their aid to non specialized agencies for implementation this paper develops a game theoretic model to explain this puzzle donors delegate aid implementation to the multilateral agency ml to strengthen the policy selectivity of aid incentivizing policy improvements in recipient countries in turn improving aid s development effectiveness bilateral donors are better off delegating aid to ml even when they are purely altruistic but disagree on how aid should be distributed across recipients key for our result to hold is that ml searches some middle ground among disagreeing donors aid selectivity in terms of both policy and poverty emerges endogenously and is credible as it is the solution to ml s optimization problem moreover the model shows that if one sufficiently large donor is policy selective in its aid allocations there is no need for other donors to be policy selective the world bank s aid program for lower income countries the international development association ida is shown to fit the assumptions and predictions of the model specifically ida is a dominant donor in most of its recipient countries and is much more policy and poverty selective than bilateral aid donors view it as a public good and contribution more to it when bilateral aid is less selective potential threats to ida s role as a dominant policy selective donor include the emergence of nontraditional donors changes in voting shares and traditional donors increasing use of earmarked contributions

aid policies and growth comment in an extraordinarily influential paper craig burnside and david dollar 2000 p 847 find that aid has a positive impact on growth in developing countries with good fiscal monetary and trade policies but has little effect in the presence of poor policies this finding has enormous policy implications the burnside and dollar 2000 henceforth bd result provides a role and strategy for foreign aid if aid stimulates growth only in countries with good policies this suggests that 1 aid can promote economic growth and 2 it is crucial that foreign aid be distributed selectively to countries that have adopted sound policies international aid agencies public policy makers and the press quickly recognized the importance of the bd findings this paper reassesses the links between aid policy and growth using more data the bd data end in 1993 we reconstruct the bd database from original sources and thus 1 add additional countries and observations to the bd data set because new information has become available since they conducted their analyses and 2 extend the data through 1997 thus using the bd methodology we reexamine whether aid influences growth in the presence of good policies given our focus on retesting bd we do not summarize the vast pre bd literature on aid and growth we just note that there was a long and inconclusive literature that was hampered by limited data availability debates about the mechanisms through which aid would affect growth and disagreements over econometric specification see gustav f papanek 1972 robert cassen 1986 paul mosley et al 1987 peter boone 1994 1996 and henrik hansen and finn tarp s 2000 review since bd found that aid boosts growth in good policy environments there have been a number of other papers reacting to their results including paul collier and jan dehn 2001 carljohan dalgaard and hansen 2001 patrick guillaumont and lisa chauvet 2001 hansen and tarp 2001 robert lensink and howard white 2001 and collier and dollar 2002 these papers conduct useful variations and extensions some of which had already figured in the pre bd literature such as introducing additional control variables using nonlinear specifications etc some of these papers confirm the message that aid only works in a good policy environment while others drive out the aid policy interaction term with other variables this literature has the usual limitations of choosing a specification without clear guidance from theory which often means there are more plausible specifications than there are data points in the sample we differentiate our paper from these others by not deviating from the bd specification thus we do not test the robustness of the results to an unlimited number of variations but instead maintain the bd methodology this paper conducts a very simple robustness check by adding new data that were unavailable to bd thus we expand the sample used over their time period and extend the data from 1993 to 1997 easterly department of economics new york university 269 mercer street new york ny 10003 center for global development and national bureau of economic research e mail william easterly nyu edu levine department of finance carlson school of management university of minnesota 321 19th avenue south minneapolis mn 55455 and national bureau of economic research e mail rlevine csom umn edu roodman center for global development 1776 massachusetts avenue nw washington dc 20036 e mail droodman cgdev org we are grateful to craig burnside for supplying data and assisting in the reconstruction of previous results without holding him responsible in any way for the work in this paper thanks also to francis ng and prarthna dayal for generous assistance with updating the sachs warner openness variable and to three anonymous referees craig burnside and henrik hansen for helpful comments 1 see for instance the world bank 1994 2001 2002 the u k department for international development 2000 president george w bush s speech march 16 2002 the announcement by the white house on creating the millennium challenge corporation white house 2002 as well as a washington post editorial february 9 2002 a financial times column by alan beattie march 11 2002 and the economist march 16 2002

aggregate implications of indivisible labor incomplete markets and labor market frictions this paper analyzes a model that features frictions an operative labor supply margin and incomplete markets we flrst provide analytic solutions to a benchmark model that includes indivisible labor and incomplete markets in the absence of trading frictions we show that the steady state levels of aggregate hours and aggregate capital stock are identical to those obtained in the economy with employment lotteries while individual employment and asset dynamics can be difierent second we introduce labor market frictions to the benchmark model we flnd that the efiect of the frictions on the response of aggregate hours to a permanent tax change is highly non linear we also flnd that there is considerable scope for substitution between voluntary and frictional nonemployment in some situations

aggregate instability under balanced budget consumption taxes a re examination we re examine the destabilizing role of balanced budget fiscal policy rules based on consumption taxation using a one sector model with infinitely lived households we consider a specification of preferences derived from jaimovich 2008 14 and jaimovich and rebelo 2009 15 which is flexible enough to encompass varying degrees of income effect when the income effect is not too large we show that there exists a laffer curve which explains the multiplicity of steady states and that non linear consumption taxation may destabilize the economy promoting expectation driven fluctuations if the elasticity of intertemporal substitution in consumption is sufficiently larger than one and the tax rate is counter cyclical with respect to consumption numerical illustrations also show that consumption taxation may be a source of instability for most oecd countries for a wide range of structural parameters configurations we finally prove the robustness of our conclusions if we consider a discrete time setup

aid quality and donor rankings this paper offers new measures of aid quality covering 38 bilateral and multilateral donors as well as new insights about the robustness and usefulness of such measures the 2005 paris declaration on aid effectiveness and the follow up 2008 accra agenda for action have focused attention on common donor practices that reduce the development impact of aid using 18 underlying indicators that capture these practices derived from the oecd dac s survey for monitoring the paris declaration the new aiddata database and the dac aid tables the authors construct an overall aid quality index and four coherently defined sub indexes on aid selectivity alignment harmonization and specialization compared with earlier indicators used in donor rankings this indicator set is more comprehensive and representative of the range of donor practices addressed in the paris declaration improving the validity reliability and robustness of rankings one of the innovations is to increase the validity of the aid quality indicators by adjusting for recipient characteristics donor aid volumes and other factors despite these improvements in data and methodology the authors caution against overinterpretation on overall indexes such as these alternative plausible assumptions regarding weights or the inclusion of additional indicators can still produce marked shifts in the ranking of some donors so that small differences in overall rankings are not meaningful moreover because the performance of some donors varies considerably across the four sub indexes these sub indexes may be more useful than the overall index in identifying donors relative strengths and weaknesses

social security and two earner households in the past decades elimination of the pay as you go system in u s has been extensively discussed and studied such an elimination would also eliminate the intra cohort redistribution done by the following policies of social security due to spousal and survivor s beneflt provisions the system redistributes mostly to single earner married households not necessarily progressive retirement beneflts are a concave function of past mean earnings hence the system redistributes from high earners to low earners finally the existence of a cap on social security taxable earnings makes the system regressive this is the flrst paper that quantifles redistributive labor supply and welfare implications of these policies using a general equilibrium life cycle model agents start out as permanently married or single and with education levels and wage proflles where the latter depend both on education and gender the household is the decision maker and decides on the labor supply of its member s and saving the aggregate production function has as inputs capital and labor aggregated by e ciency elimination of these policies results in a 6 1 increase in married female labor force participation rate the middle income single earner married households experience the largest welfare losses whereas the high income two earner households together with high income single households experience the largest welfare gains

spatially uniform versus spatially heterogeneous compensation payments for biodiversity enhancing land use measures the importance of compensation payments for biodiversity enhancing land use measures has grown over the past decade particularly in connection with agri environmental policy given that both the costs and the benefits of biodiversity enhancing land use measures are subject to spatial variation the criterion of cost effectiveness calls for spatially heterogeneous compensation payments however when deciding whether to implement uniform or heterogeneous compensation payments the regulator has to compare the disadvantage of uniform payments in terms of cost effectiveness with the disadvantages of spatially heterogeneous payments to help resolve this issue this paper provides a simple ecological economic model that allows the reduced cost effectiveness associated with uniform payments for biodiversity enhancing land use measures to be assessed for different types of benefit and cost functions

labour supply the roles of human capital and the extensive margin we specify and estimate a life cycle labour supply model that expands on earlier work by simultaneously including human capital accumulation saving and bequests an active extensive margin a realistic specification of the progressive tax structure and the social security system and an accounting for private pensions and health expenditures by incorporating all these features we develop new insights into how taxes affect life cycle labour supply for instance we find that labour supply elasticities vary in important ways with age education and the tax structure itself we also show how human capital affects elasticities differently on the intensive versus extensive margins

aid and growth regressions this paper examines the relationship between foreign aid and growth in real gdp per capita as it emerges from simple augmentations of popular cross country growth specifications it is shown that aid in all likelihood increases the growth rate and this result is not conditional on good policy there are however decreasing returns to aid and the estimated effectiveness of aid is highly sensitive to the choice of estimator and the set of control variables when investment and human capital are controlled for no positive effect of aid is found yet aid continues to impact on growth via investment we conclude by stressing the need for more theoretical work before this kind of cross country regressions are used for policy purposes

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