time orientation and asset prices we analyze a general equilibrium asset pricing model where a small subset of the consumers investors have a short run urge to save that is their attitude toward consumption in the long run is a standard one f they do place zero weight on consumption far enough out in the future f but their short run effective rates of discount may be negative our model which is an elaboration on the framework proposed by faruk gul and wolfgang pesendorfer does not feature time inconsistencies thus we view consumers as fully rational but subject to specific internal frictions in the form of temptation and self control problems the model nests the mehra prescott model and we use it as a way of interpreting the wealth and asset pricing data some aspects of these data we argue can possibly be better understood using our model than the standard one r 2002 published by elsevier science b v

temptation and social security in a dynastic framework abstract we investigate welfare and aggregate implications of a pay as you go payg social security system in a dynastic framework in which individuals have self control problems the presence of self control problems induces individuals to save less because of their urge for temptation towards current consumption individuals efforts to balance between the short term urge for temptation and the long term commitment for consumption smoothing result in self control costs in this environment payg social security works as a self control cost reducing device in contrast the presence of altruism induces individuals to save more this in turn mitigates the adverse effects of self control problems and payg social security on savings but magnifies the self control costs we find that in our environment the adverse welfare effects of a payg system are further mitigated relative to the environments that incorporate altruism and self control issues separately however the level of mitigation is quite modest

time inconsistent preferences and social security revisited in continuous time abstract imrohoroglu et al 2003 prove that it is impossible in a three period partial equilibrium model for social security to improve the welfare of a naive quasi hyperbolic agent if the program has a negative net present value this paper first generalizes their impossibility theorem to a continuous time setting and then proves analytically that no discount function exists that can rationalize a social security program with a negative net present value

the effects of welfare and tax reform the material well being of single mothers in the 1980s and 1990s abstract the tax and welfare programs that provide income and in kind benefits to single mothers have changed dramatically in recent years these changes began as far back as the mid 1980s and culminated with the 1996 welfare law that ended welfare as we knew it these tax and welfare changes have sharply increased the employment of single mothers and cut welfare rolls however little is know about the effects of these policy changes on the material well being of single mothers and their children studies of those leaving welfare have found that a substantial percentage have problems paying rent purchasing enough food and paying utility bills other studies found a decline in income among the worst off single mothers after 1994 or 1995 the goal of this paper is to examine the material well being of single mothers and their families before and after recent welfare and tax reforms using data from two nationally representative household surveys we examine the consumption patterns of single mothers and their families from 1984 2000 we find that the material conditions of single mothers did not decline in recent years either in absolute terms or relative to single childless women or married mothers this pattern holds for the average single mother as well as for low educated single mothers at both the 15th and 25th percentiles of the consumption distribution in most cases our evidence suggests that the material conditions of single mothers have improved slightly

the socioeconomic consequences of teen childbearing reconsidered we present new estimates of the consequences of teen childbearing that take into account observed and unobserved family background heterogeneity comparing sisters who have timed their first births at different ages the estimation is conducted using data from the u s national longitudinal survey of young women excerpt

diffusion of renewable energy technologies in developing countries a case study of biogas engines in india abstract this paper presents a case study of promoting biogas engines in india using an analytic framework involving i characteristics of the technology ii characteristics of the users iii macro environment iv role of government and other organizations and v structure of the market the case study shows that although the technology was economic from the viewpoint of society it was not adopted by the farmers on a large scale due to the unfavorable macro environment created by the government and because of an inappropriate pricing policy by the manufacturer

the optimal level of social security benefits the optimal level of social security benefits depends on balancing the protection that these benefits offer to those who lack the foresight to provide for their own old age against the welfare costs of distorting economic behavior the primary such cost is the distortion in private saving the present paper derives the level of social security benefits that is optimal in three basic cases in the first section the paper derives the optimal level of benefits for an economy in which all individuals do not anticipate retirement at all and therefore do no saving the second and third sections then derive optimal benefits for two different definitions of incomplete myopia

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

time inconsistent preferences and social security in this paper we examine the role of social security in an economy populated by overlapping generations of individuals with time inconsistent preferences who face mortality risk individual income risk and borrowing constraints we find that unfunded social security lowers the capital stock output and consumption for consumers with time consistent or time inconsistent preferences however it may raise or lower welfare depending on the strength of time inconsistency

diffusion of rural innovations some analytical issues and the case of wood burning stoves abstract the literature on the diffusion of rural innovations in third world countries reveals a spectrum of approaches to the diffusion process it is argued here that the effectiveness of a particular approach in the diffusion of particular innovations would depend on the technical the economic and the social characteristics of the innovations a typology of innovations in terms of these characteristics has been drawn up this provides the analytical framework within which the instance of wood burning stoves is concerned a priori the characteristics of this innovation are seen to be such as to necessitate the close involvement of the users in the design process itself they point to the likely inappropriateness of the usual top down approach to diffusion available evidence relating to actual experience with promoting wood burning stoves is seen to bear this out

the value of children inter generational support fertility and human capital abstract this paper offers robust empirical evidence of a darwinian pro natalist mechanism parents can improve their old age support with an additional child using the incidence of first born twins as an instrument for fertility outcomes i find that chinese senior parents with more children receive more financial transfers and are more likely to co reside with an adult child they are also less likely to work past retirement age the estimated effects are large despite the evidence that adult children from larger families are less educated and earn significantly less interestingly the effect of an increase in the number of children on old age support does not depend on the child s gender

slipping into and out of poverty the dynamics of spells this paper examines the dynamics of poverty previous analyses have examined either fluctuations in the male heads earnings or the frequency of poverty periods over a fixed time frame our approach depends on a definition of spells of poverty using this methodology we find that the majority of poor persons at any time are in the midst of a rather long spell of poverty the methodology also allows us to estimate that less than 40 percent of poverty spells begin because of a drop in the heads earnings while 60 percent of the spells end when the heads earnings increase thus researchers must focus on household formation decisions and on the behavior of secondary family members there has been a dramatic resurgence recently of discussion of the underclass the discussion is reminiscent of debates about poverty during the 1960s when the notions of a culture of poverty particularly as popularized by michael harrington s other america 1962 dominated both intellectual and policy thinking the idea of an underclass seems inconsistent however with much of the research on the dynamics of poverty during the 1970s that research using new longitudinal data seemed to show that the bulk of the poor were poor for only a few years the research also showed that the poor were a very heterogeneous group including a small minority of persistently poor the persistence of poverty is of interest both for understanding the phenomenon and for developing policy claims about dependency and separate life styles among the poor rest on assumptions about the long term nature of poverty questions

when it rains it pours under what circumstances does job loss lead to divorce much of the previous research that has examined the effect of job loss on the probability of divorce either rely on data from the 1970s 80s data from european countries or focus on aggregate divorce rates this study uses u s micro data from 2000 to 2012 thus including effects of the great recession to examine how displacement i e exogenous job loss affects the probability of divorce the author finds displacement significantly increases the probability of divorce but only if the husband is the spouse that is displaced and his earnings represented approximately half or less of the household s earnings prior to displacement similarly results show that the probability of divorce increases if the wife is employed and as her earnings increase while the mechanism behind these asymmetric results remains unclear these results are consistent with recent research that finds a destabilizing effect on marriages when a wife earns more than her husband

soil erosion and labor shortages in the andes with special reference to bolivia 1953ndash 1991 implications for conservation with development abstract many claims in support of soil conservation policies have been flawed by excessively deterministic reasoning and unwarranted spatial overaggregation a case study remedying these flaws demonstrates that soil erosion in the bolivian andes worsened during recent decades 1953 91 due to changes in production as peasants shifted labor from conservation techniques to nonfarm employment these findings reflect in three policy issues concerning sustainable resource management oriented toward development conservation with development are discussed a environmental consequences and economic causes of increased nonfarm employment by part time peasant farmers b environment related aspects of technology innovation and technique modifications in labor scarce peasant production and c the environmental perceptions of peasant farmers in participatory development planning

farmers financing of agricultural research in israel abstract agricultural research is mostly a public undertaking in israel as in many other countries farmers participate in the finance of research through taxes imposed by farm organizations on the marketed products farmers contribution ranges from 8 of research outlay in tomatoes to 79 in cotton strength of organization and ease of collection were the major factors affecting this share in general as inflation eroded the real value of government s finance the farmers increased their share representatives of farmers organization participate in the bodies that approve grants to proposed research projects it was found that the higher the share of farmers finance the larger the part of short term research directed at immediate outcomes and the smaller the part of long term more basic research the tendency of the farmers to prefer short term applicable research may reflect both their familiarity with practical problems and a comparatively high degree of risk aversion it is not clear how farmers participation in the direction of research which is based on their financial contribution affects the efficiency of resource allocation to the agricultural sciences

trends and projections for bangladeshi food production an alternative viewpoint abstract this article analyses growth in bangladeshi food production and yields by reviewing past evidence and critically examining the contribution of james k boyce general statistical evidence is considered on whether the past growth rate is being sustained the evidence suggests that past growth is unlikely to continue data from a recent field survey in two different areas of bangladesh add weight to this view on both ecological and economic grounds it seems likely that bangladesh s ability to feed its population will continue to decline

the cyclical and secular behaviour of the labour input comparing efficiency units and hours worked summary a monthly labour input series designed to correct for the fact that all hours worked are not of the same quality is constructed and its properties compared with unadjusted hours worked this efficiency units series is constructed from bls data on hours worked and earnings by age and sex the cyclical fluctuations displayed by the efficiency units series are smaller on average than those displayed by hours worked although the difference is not large however the secular behaviour of the series is quite different hours worked per capita displays a significant positive trend while efficiency units per capita does not

quasi hyperbolic discounting and retirement abstract some people have self control problems regularly this paper adds endogenous retirement to laibson s quasi hyperbolic discounting savings model quarterly journal of economics 112 1997 443 477 earlier selves think that the deciding self tends to retire too early and may save less to induce later retirement still earlier selves may think the pre retirement self does this too much saving more to induce early retirement the consumption pattern may be different from that with exponential discounting other observational non equivalence includes the impact of changing mandatory retirement rules or work incentives on savings and a possibly negative marginal propensity to consume out of increased future earnings naive agents are briefly considered

after the big bang obstacles to the emergence of the rule of law in post communist societies when russia launched mass privatization it was widely believed that it would create a powerful constituency for the rule of law that didn t happen we present a dynamic equilibrium model of the political demand for the rule of law and show that beneficiaries of mass privatization may fail to demand the rule of law even if it is the pareto efficient rule of the game the reason is that uncertainty about the legal regime can lead to asset stripping and stripping can give agents an interest in prolonging the absence of the rule of law this abstract was borrowed from another version of this item

lifetime earnings and the vietnam era draft lottery evidence from social security administrative records errata the randomly assigned risk of induction generated by the draft lottery is used to construct estimates of the effect of veteran status on civilian earnings these estimates are not biased by the fact that certain types of men are more likely than others to service in the military social security administrative records indicate that in the early 1980s long after their service in vietnam had ended the earnings of white veterans were approximately 15 percent less than the earnings of comparable nonveterans copyright 1990 by american economic association

sources of innovation in agricultural technology abstract this paper focuses attention on environmental and biological characteristics of agriculture which shape the process of technical innovation the interaction of natural selection and human purposive selection and experimentation is shown to result in a continuous process of innovation placing farmers in the informal r and d systems as well as scientists in formal r and d systems in an innovative treadmill the importance and limitations of informal r and d are reviewed a discussion of the characteristics and potential of formal r and d systems leads to the identification of some major problems of policy inherent in and specific to the organization and management of agricultural research resources these include genetic vulnerability choices between environmentally specific or widely adapted technologies the location of research activity the linkages between agricultural producers and scientists and methods for maintaining and strengthening informal r and d systems

the economic consequences of unwed motherhood using twin births as a natural experiment social scientists have long concluded that premarital childbearing exacerbates problems of both poverty and family instability out of wedlock and adolescent childbearing may reduce a mothers educational attainment lower the probability of her eventual marriage increase her probability of welfare recipiency and decrease family income the authors use an exogenous fertility event the birth of twins to estimate the economic effects of unplanned births the approach compares the economic outcomes of women experiencing premarital twin first births to those experiencing premarital single first births in the attempt to identify the consequences of an unplanned birth upon womens future fertility and marital decisions education labor force participation labor earnings welfare receipt and poverty status 1970 and 1980 us census micro data are used to identify twin births to unmarried women analysis found large short term effects of unplanned births on labor force participation poverty and welfare recipiency among unwed mothers but not among married mothers furthermore most adverse economic effects of unplanned motherhood dissipate over time for whites but larger and more persistent negative effects weigh upon black unwed mothers

social security and self control preferences abstract we analyze the welfare effects of an unfunded social security system we do so using an overlapping generations economy wherein agents have self control preferences face mortality risk individual income risk and borrowing constraints given our specification of preferences unfunded social security helps reduce the agents temptation to consume in every period consequently the welfare costs it otherwise entails are substantially mitigated while both social security and self control when considered separately reduce welfare their combination renders this effect considerably less severe moreover if the cost of resisting temptation is very high the introduction of social security might even improve welfare

a welfare analysis of social security in a dynastic framework in this article we study the welfare effects of unfunded social security in a general equilibrium model populated with overlapping generations of altruistic individuals that differ in lifetime expectancy and earnings ability contrary to previous research our results indicate that steady state welfare increases with social security for most households although by very different amounts this result is mainly due to two factors first the presence of two sided altruism significantly mitigates the crowding out effect of unfunded social security second ability shocks and uncertain lifetimes generate significant heterogeneity among households to yield different induced preferences for social security

re evaluating the role of energy efficiency standards a behavioral economics approach abstract the economic models that prescribe pigovian taxation as the first best means of reducing energy related externalities are typically based on the neoclassical model of rational consumer choice yet consumer behavior in markets for energy using durables is generally thought to be far from efficient giving rise to the concept of the energy efficiency gap this paper presents a welfare analysis of energy policies that is based on a behavioral model of temptation and self control introduced by gul and pesendorfer 23 24 we find that in the presence of temptation i pigovian taxes alone do not yield a first best outcome ii when viewed as substitutes energy efficiency standards can dominate pigovian taxes and iii a policy combining standards with a pigovian tax can yield higher social welfare than a pigovian tax alone implying that the two instruments should be viewed as complements rather than substitutes

did unilateral divorce raise divorce rates evidence from panel data since early 1996 at least eight states have begun to consider rolling back unilateral and no fault divorce a major reversal of the liberalizing trend in divorce laws which began around 1970 the proponents of tightening the divorce regime often argue that making divorce more difficult will strengthen families however both theoretical and empirical evidence is decidedly mixed over whether the no fault revolution actually contributed to the sharp increase in divorce rates in the united states observed over the last 30 years in this paper i address the dispute by using a panel of state level divorce rates including state specific trends allows unobserved state divorce propensities to trend linearly and even quadratically over time and reveals that unilateral divorce raised divorce rates significantly and strongly excerpt

the economic consequences of absent parents we examine the effects of family structure on economic resources controlling for unobservable family characteristics in the year following a divorce family income falls by 41 percent and family food consumption falls by 18 percent six or more years later the family income of the average child whose parent remains unmarried is 45 percent lower than it would have been if the divorce had not occurred marriage raises the long run family income of children born to single parents by 45 percent these estimates are substantially smaller than the losses that are implied by cross sectional comparisons across family types

a multiple source of innovation model of agricultural research and technology promotion abstract two models of agricultural research and technology diffusion are described and contrasted the central source of innovation model frequently underlies the theories and rhetoric of agricultural research and extension institutions the multiple source of innovation model places agricultural research and diffusion processes in the historical political economic agroclimatic and institutional context in which technological change takes place the paper discusses the evidence and reasons for the dominance of the central model and reviews the significance of the multiple source model for agricultural research policy

measuring self control problems a structural estimation we perform a structural estimation of the preference parameters in a buffer stock consumption model augmented with temptation disutility we adopt a two stage method of simulated moments methodology to match our simulated moments with those observed in the us survey of consumer finances to identify the parameters we use liquid and quasi liquid retirement wealth holdings at different ages as target moments we find evidence of a significantly positive degree of temptation and estimates under the unrestricted model are more precise than estimates under the restricted model with no temptation overall a model with temptation preferences explains better the observed target moments

does compulsory school attendance affect schooling and earnings we establish that season of birth is related to educational attainment because of school start age policy and compulsory school attendance laws individuals born in the beginning of the year start school at an older age and can therefore drop out after completing less schooling than individuals born near the end of the year roughly 25 percent of potential dropouts remain in school because of compulsory schooling laws we estimate the impact of compulsory schooling on earnings by using quarter of birth as an instrument for education the instrumental variables estimate of the return to education is close to the ordinary least squares estimate suggesting that there is little bias in conventional estimates every developed country in the world has a compulsory schooling requirement yet little is known about the effect these laws have on educational attainment and earnings 1 this paper exploits an unusual natural experiment to estimate the impact of compulsory schooling laws in the united states the experiment stems from the fact that children born in different months of the year start school at different ages while compulsory schooling laws generally require students to remain in school until their sixteenth or seventeenth birthday in effect the interaction of school entry requirements and compulsory schooling laws compel students born

equilibrium welfare and government policy with quasi geometric discounting abstract we consider a representative agent equilibrium model where the consumer has quasi geometric discounting and cannot commit to future actions we restrict attention to a parametric class for preferences and technology and solve for time consistent competitive equilibria globally and explicitly we then characterize the welfare properties of competitive equilibria and compare them to that of a planning problem the planner is a consumer representative who without commitment but in a time consistent way maximizes his or her present value utility subject to resource constraints the competitive equilibrium results in strictly higher welfare than the planning problem whenever the discounting is not geometric journal of economic literature classification numbers e21 e61 e91

social security reform with self control preferences abstract this paper analyzes a fully funded social security system under the assumption that agents face temptation issues agents are required to save through individually managed personal security accounts without and with mandatory annuitization when the analysis is restricted to crra preferences our results are congruent with the literature in indicating that the complete elimination of social security is among the reform scenarios that maximize welfare however when self control preferences are introduced and as the intensity of self control becomes progressively more severe the social security elimination scenario loses ground very rapidly in fact in the case of relatively severe temptation the elimination of social security becomes the least desirable alternative under the light of the above findings any reform proposal regarding the social security system should consider departures from standard preferences to preference specifications suitable for dealing with preference reversals

systems of innovation theory and the changing architecture of agricultural research in africa abstract this paper examines the on going evolution of the organisational architecture of agricultural research in africa once considered a rural backwater populated by agronomists extension agents and farmers agricultural research is now being explicitly placed within global debates about innovation technology institutions and development this is reflected in a growing interest in the use of systems of innovation theory to both understand and reform innovation processes within agriculture the basic argument put forward in the paper is that the conception of a global agricultural research system and associated efforts to create a coordinated multi layered supra national research infrastructure are at odds with both the realities of research at national level and the bio physical and socio economic heterogeneity that characterises rural africa it is suggested that a less directive approach to support for agricultural research is required to allow national characteristics and differences to come to the fore and to give more room for the development of the all important demand side

annuities and individual welfare advancing annuity demand theory we present suffcient conditions for the optimality of full annuitization under market completeness that are substantially less restrictive than those used by yaari 1965 we examine demand with market incompleteness finding that positive annuitization remains optimal widely but complete annuitization does not how uninsured medical expenses affect demand for illiquid annuities depends critically on the timing of the risk a new set of calculations with optimal consumption trajectories very different from available annuity income streams still shows a preference for considerable annuitization suggesting that limited annuity purchases are plausibly due to psychological or behavioral biases

consumption savings decisions with quasi geometric discounting we study the consumption savings problem of an infinitely lived rational consumer who has time inconsistent preferences in the form of quasi geometric discounting the consumer operates a weakly concave production function and must simply divide current resources into current consumption and savings there is no uncertainty a solution to the consumer s problem is a subgame perfect equilibrium of a dynamic game between the consumer s successive selves we show that this game has a continuum of equilibria in stationary markov strategies not only is the stationary point of the consumer s asset holdings indeterminate but each stationary point has a continuum of dynamic paths converging to it the savings policy rules underlying these dynamic paths are step functions

market analysis technical change and income distribution in semi subsistence agriculture the case of bangladesh for the first time the model developed by hayami and herdt is applied to determine gains from modern varieties of rice in bangladesh and the distribution of these gains between consumers and producers the results suggest that consumers surplus is much greater than it would have been had the high yielding crop varieties hyvs not been introduced by keeping the real price lower than it would have been otherwise the modern varieties have tended to be income equalizing for urban consumers the hayami herdt partial model even suggests that given the relatively inelastic demand for rice in bangladesh the real cash income of producers has risen slightly as a result of these new technologies in reality however the impact of these changes on incomes of farmers and the distribution of income between those involved in production is more complex it is suggested that if a less partial view is taken and if account is taken of lower cost of obtaining home consumed produce the increase in income may be greater in any event there are dangers in using such a partial model to predict the developmental consequences of technological changes affecting a staple crop and attention needs also to be given to the possibility that the supply curve may not have the simple form and pivot in the way supposed by hayami and herdt while the hayami herdt model is simple to apply it is best used as a first approximation or starting point rather than a final solution it ignores a number of criteria that could be important in assessing new agricultural technologies such as their impact on the variability of benefits to producers and consumers and their consequences for sustainability of production furthermore the hayami herdt model does not deal specifically with changes in factor shares in farm production nor does it consider the impact on income distribution of the ownership and control of critical input like irrigation and imperfection in the rural credit market it is pointed out in our paper that the adoption of hyvs has been associated with important variations in factor shares in bangladeshi rice production analysis of available farm level data indicates that the relative share of labour has fallen suggesting an uneven distribution of gains from technological changes between the owners of non labour resources and those of labour resources however the absolute share of labour has increased and it seems that rural employment has risen as result of the new technologies

self control and the theory of consumption to study the behavior of agents who are susceptible to temptation in infinite horizon consumption problems under uncertainty we define and characterize dynamic self control dsc preferences dsc preferences are recursive and separable in economies with dsc agents equilibria exist but may be inefficient in such equilibria steady state consumption is independent of initial endowments and increases in self control increasing the preference for commitment while keeping self control constant increases the equity premium removing nonbinding constraints changes equilibrium allocations and prices debt contracts can be sustained even if the only feasible punishment for default is the termination of the contract

the effect of welfare payments on the marriage and fertility behavior of unwed mothers results from a twins experiment we study the relationship between welfare benefits and the time to first marriage and time to next birth among initially unwed mothers we use twin births to generate random within state variation in benefits effectively controlling for unobservables that may confound the relationship between welfare payments and behavior higher base welfare benefits 1 lead unwed white mothers to forestall their eventual marriage and 2 lead unwed black mothers to hasten their next birth the magnitudes of these effects are fairly modest moreover we find no evidence that the marginal benefit paid at the birth of an additional child the focus of the family cap debate affects fertility

children and their parents labor supply evidence from exogenous variation in family size although theoretical models of labor supply and the family are well developed there are few credible estimates of key empirical relationships in the work family nexus this study uses a new instrumental variable the sex composition of the first two births in families with at least two children to estimate the effect of additional children on parents labor supply in the united states instrumental variables estimates using the sex mix are substantial but smaller than the corresponding ordinary least squares ols estimates moreover unlike the ols estimates the female labor supply effects estimated using sex mix instruments appear to be absent among more educated women and women with high wage husbands we also find that married women who have a third child reduce their labor supply by as much as women in the full sample while there is no relationship between wives child bearing and husbands labor supply excerpt

more power to the pill the impact of contraceptive freedom on women s life cycle labor supply the release of enovid in 1960 the first birth control pill afforded u s women unprecedented freedom to plan childbearing and their careers this paper uses plausibly exogenous variation in state consent laws to evaluate the causal impact of the pill on the timing of first births and extent and intensity of women s labor force participation the results suggest that legal access to the pill before age 21 significantly reduced the likelihood of a first birth before age 22 increased the number of women in the paid labor force and raised the number of annual hours worked

bounding causal effects using data from a contaminated natural experiment analysing the effects of teenage childbearing in this paper we consider what can be learned about causal effects when one uses a contaminated instrumental variable in particular we consider what inferences can be made about the causal effect of teenage childbearing on a teen mother s subsequent outcomes when we use the natural experiment of miscarriages to form an instrumental variable for teen births miscarriages might not meet all of the conditions required for an instrumental variable to identify such causal effects for all of the observations in our sample however it is an appropriate instrumental variable for some women namely those pregnant women who experience a random miscarriage although information from typical data sources does not allow one to identify these women we show that one can adapt results from horowitz and manski 1995 on identification with data from contaminated samples to construct informative bounds on the causal effect of teenage childbearing we use these bounds to re examine the effects of early chilbearing on the teen mother s subsequent educational and labour market attainment as considered in hotz mcelroy and sanders 1995a 1995b consistent with their study these bounds indicate that women who have births as teens have higher labour market earnings and hours worked compared to what they would have attained if their childbearing had been delayed

motherhood and female labor force participation evidence from infertility shocks women are underrepresented in the paid labor force in both developed and developing countries recent scholarship has argued that labor force differentials are not due to gender per se but can be attributed to the fact that women disproportionately face the responsibilities associated with bearing and raising children while the negative relationship between the presence of children and participation in the labor force is well established interpretation of this relationship is complicated by the endogeneity of fertility the number of children a woman has is a choice variable which could be influenced by her labor force participation additionally there are likely to be omitted factors that influence both fertility and labor force participation for instance women with high career based unobservables such as ambition or talent may choose to have fewer or no children and these women may be overrepresented in the labor force thus the observed negative relationship between children and labor force participation could be spurious several studies have exploited exogenous changes in family size in order to identify the

why research partnerships really matter innovation theory institutional arrangements and implications for developing new technology for the poor abstract this paper explores the conceptual basis for existing and emergent institutional patterns in the context of partnership approaches to technology development drawing examples from recent studies of private enterprise activity in india smallholder horticulture it suggests that agricultural innovation as a process involves a wider range of organizational types than the conventional policy focus on public sector research organizations would tend to suggest it uses the concept of a national innovation system to argue that a partnership approach is adopted as a core methodology for engaging science and technology development with the livelihood demands of the poor

temptation driven behavior and taxation a quantitative analysis in a life cycle model i introduction a central research question in the dynamic fiscal policy literature during the last 30 years or so is whether under fairly general modeling choices the government should impose a positive tax on capital income in the long run the original answer to this question is negative and is due to the seminal papers by chamley 1986 and judd 1985 who established that in the context of a standard neoclassical growth model with infinitely lived individuals an optimal income tax policy entails taxing capital at confiscatory rates in the short run and setting capital income taxes equal to zero in the long run only labor income should be taxed in the long run since then several modeling choices that cast doubt on the validity of this result were identified in the literature imrohoroglu 1998 showed that the optimal capital income tax rate is strictly positive in an overlapping generations olg setting where individuals face idiosyncratic earnings risk borrowing constraints and life span uncertainty conesa kitao and krueger 2009 extended imrohoroglu 1998 by adding a labor leisure choice they demonstrated that the optimal capital income tax rate is equal to 36 and concluded that this high rate is mainly driven by the life cycle structure of the model in contrast krusell kuruscu and smith 2010 analytically showed that within a class of ramsey tax schemes the optimal capital income tax rate should be negative that is savings should be subsidized when agents have self control problems moreover in the special case where consumers succumb completely to temptation ramsey taxes deliver first best welfare outcomes and in contrast to the chamley judd result the optimum calls for a subsidy to savings however an integrated assessment of the combined effects of the relevant trade offs both along the dimension of differences in preferences and along the dimension of the scope of capital income taxation versus labor income taxation is missing from all previous studies in both social security and capital taxation literature and this paper aims to bridge the gap in the literature and contribute in this aspect to the best of our knowledge this paper is the first study that introduces temptation driven preferences in a quantitative model aiming to tackle the question on the optimal capital income tax before proceeding to specifically articulate this paper s contribution to the literature we consider critical to address a question that lies at the very core of our line of research namely why fiscal policy models with time inconsistent or self control preferences are relevant in the first place initially the literature pioneered by strotz 1956 and phelps and poliak 1968 corroborated evidence coming from both introspection and experiments that agents exhibit preference reversals as time passes different strands within this literature have suggested that these preference reversals could be induced by either time inconsistent preferences see laibson 1997 or self control preferences gul and pesendorfer 2004 time inconsistent preferences typically assume that agents have sequences of different selves each valuing consumption streams in a unique way in contrast gul and pesendorfer 2004 provide a dynamically consistent model suitable for addressing preference reversals that does not necessitate splitting up the consumer in multiple selves that is self control preferences these preferences describe an individual that in every period is tempted to consume his entire endowment when he consumes less than his endowment he incurs a disutility cost that stems from exercising self control that is self control cost optimal behavior trades off the temptation to consume vis a vis the long run self interest of the individual 1 alongside these theoretical underpinnings there is sound empirical and experimental evidence that agents suffer from self control problems