alternative estimates of the effect of schooling on earnings this is the publisher s version it can also be found here http www mitpressjournals org doi pdf 10 1162 003465300558542

nonparametric bounds on the returns to language skills this paper applies the theoretical literature on nonparametric bounds on treatment effects to the estimation of how limited english proficiency lep affects wages and employment opportunities for hispanic workers in the united states i analyse the identifying power of several weak assumptions on treatment response and selection and stress the interactions between lep and education occupation and immigration status i show that the combination of two weak but credible assumptions provides informative upper bounds on the returns to language skills for certain subgroups of the population adding age at arrival as a monotone instrumental variable also provides informative lower bounds copyright 2005 john wiley sons ltd

global commodity chains and endogenous growth export dynamism and development in mexico and honduras summary mexico s garment exports to the united states soared in the mid 1990s and recently honduras has become one of the fastest growing exporters in the americas we find little evidence that the apparel sector s dynamism is generating conditions for endogenous growth and sustainable development in either country however in spite of differences in the industrial organization of export oriented garment production in mexico and honduras the countries face similar challenges regulatory regimes with rules of origin designed to benefit us fabric manufacturers competitive pressures from china and the broader institutional and macroeconomic environments associated with the region s liberalization strategy

head start and the distribution of long term education and labor market outcomes we investigate the effect of head start on education and wage income for individuals in their 30s in the nlsy79 we contribute to the existing literature by examining effects across outcome distrib

estimating income poverty in the presence of measurement error and missing data problems reliable measures of poverty are an essential statistical tool for public policies aimed at reducing poverty in this article we consider the reliability of income poverty measures based on survey data which are typically plagued by missing data and measurement error neglecting these problems can bias the estimated poverty rates we show how to derive upper and lower bounds for the population poverty rate using the sample evidence an upper bound on the probability of misclassifying people into poor and nonpoor and instrumental or monotone instrumental variable assumptions by using the european community household panel we compute bounds for the poverty rate in 10 european countries and study the sensitivity of poverty comparisons across countries to missing data and measurement error problems supplemental materials for this article may be downloaded from the jbes website

financial innovation and information the role of derivatives when a market for information exists we study the effects of financial innovation in a model of endogenous information acquisition we determine the conditions under which the introduction of a derivative written on an existing stock increases or decreases the incentive to purchase information we show that financial innovation produces some effects which hold across informational structures and others which differ the former coincide with the few empirical results that are robust in the literature effects on prices risk premia and volatility while the latter coincide with the ones that differ experiment by experiment effects on volume correlation between volume and volatility and market informational efficiency copyright 2002 oxford university press

investor valuation of the abandonment option abstract we investigate whether investors price the option to abandon a firm at its exit value theory prices this real option as an american put with both a stochastic strike price exit value and a stochastic value of the underlying security the value of cash flows the empirical implications are that firm value increases in exit value after controlling for expected going concern cash flows and that more generalizable assets produce more abandonment option value using discounted earnings forecasts to proxy for expected cash flows and prior literature to categorize asset generalizability we find strong support for the predictions of abandonment option theory

the estimation of wage gains and welfare gains in self selection models the authors modify the basic self sele ction model for the effects ofeducation training unions and other activities on wages by including heterogeneity of rewards to the activity i e diffe rences across individuals in the rate of return to the activity the authors sho w that such heterogeneity creates a new form of selectionbias they provide tes ts for its presence and draw out its implications for the wage and welfare gains to the activity an empirical application provides strong support for such hete rogeneityin one particular training program copyright 1987 by mit press

identification issues in the public private wage gap with an application to italy this paper reviews some of the standard assumptions that are imposed in order to estimate the average public private wage gap and that are mainly related to the possible selection of the sector there are two contributions to the existing public private wage gap literature one is a better understanding of the identified parameters standard estimators identify a local effect late which in general cannot be generalized to the entire population as instead is almost always done the other is the partial identification of the population average treatment effect with an instrumental variable to the best of my knowledge this is the first paper in this literature that employs bounds the technique is applied to male workers in italy for compliers late estimates a wage advantage from working in the public sector greater than 30 this return is within the narrowest bounds on the population average treatment effect that are consistent even with a much smaller gap about 15 or more

the effect of additional funds for low ability pupils a non parametric bounds analysis this article investigates the effect of a policy measure that gives secondary schools additional resources for low ability pupils schools are free in deciding how to spend the additional money i use a non parametric bounds analysis to estimate upper and lower bounds on the effect of additional funds on examination results of pupils first i investigate what can be concluded without imposing assumptions next i layer weak non parametric assumptions to tighten the bounds the tightest bounds show that the additional school funds significantly increase the probability that a pupil passes the examination at the end of secondary education

upgrading in global value chains lessons from latin american clusters it has been shown that clustering helps local enterprises in industrial districts overcome growth constraints and compete in distant markets in advanced and less developed countries nevertheless recent contributions have stressed that more attention needs to be paid to external linkages and to the role played by global buyers to foster upgrading at cluster levels in this study we contribute to this debate focusing on the analysis of the relationships existing between clustering global value chains upgrading and sectoral patterns of innovation in latin america we find that sectoral specificities matter and influence the mode and the extent of upgrading in clusters integrated in global value chains

what drives the commodity price beta of oil industry stocks we test theoretical drivers of the oil price beta of oil industry stocks the strongest statistical and economic support comes for market conditions type variables as the prime drivers namely oil price bond rate volatility of oil returns and cost of carry though statistically significant exogenous firm characteristics and oil firms financing decisions have less compelling economic significance there is weaker support for the prediction that financial risk management reduces the exposure of oil stocks to crude oil price variation finally extended modelling shows that mean reversion in oil prices also helps explain cross sectional variation in the oil beta

the effect of derivative assets on information acquisition and price behavior in a rational expectations equilibrium this article shows that introducing derivative assets increases incentives to collect information about asset payoffs the increase in information collection makes the price of the underlying asset more informative and causes the expected price to increase extending the model to a dynamic setting with multiple risky assets we find the introducing derivative assets for one asset increases the expected prices of positively correlated assets and reduces price reaction to future earnings announcements these findings are consistent with the bulk of the empirical evidence on the relationship between the introduction of derivative assets and the behavior of asset prices article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

the returns to schooling a selectivity bias approach with a continuous choice variable the essence of selection bias is that we do not observe nonoptimal choices this applies whether the choice variable is discrete or continuous this paper extends the selection bias methodology to the case where the choice variable is continuous and the choice set is ordered the leading practical application of this analysis is the schooling choice problem schooling is treated as a continuous choice variable and selectivity corrected rates of return are estimated the findings suggest selectivity is of considerable importance and support the comparative advantage hypothesis of willis and rosen 18

asymmetric information and options in an extension of the kyle 1985 model of continuous insider trading it is shown that asymmetric information can make it impossible to price options by arbitrage even when an option would appear to be redundant its introduction into the market can cause the volatility of the underlying asset to become stochastic this eliminates the potential for dynamically replicating the option the change in the price process of the asset reflects a change in the information transmitted by volume and prices when the option is traded article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

programme evaluation with multiple treatments this paper reviews the main identification and estimation strategies for microeconometric policy evaluation particular emphasis is laid on evaluating policies consisting of multiple programmes which is of high relevance in practice for example active labour market policies may consist of different training programmes employment programmes and wage subsidies similarly sickness rehabilitation policies often offer different vocational as well as non vocational rehabilitation measures first the main identification strategies control for confounding variables difference in difference instrumental variable and regression discontinuity identification are discussed in the multiple programme setting thereafter the different nonparametric matching and weighting estimators of the average treatment effects and their properties are examined download discussion paper pdf 484 kb

globalisation and unequalisation what can be learned from value chain analysis although many have gained from the process of globalisation there remains a stubbornly large number of people living in absolute poverty and a rise in inequality within and between countries the issue is thus not whether to participate in the global economy but how to do so in a manner which provides for sustainable and equitable income growth this study shows how value chain analysis can be used to chart the growing disjuncture between global economic activity and global income distribution and to provide causal explanations for this outcome in so doing value chain analysis provides valuable insights into policy formulation and implementation

policy analysis and advocacy for livestock based development the gap between household level analysis and higher level models the dichotomy in approaches to policy analysis for developing countries livestock sectors is presented substantial experience and information generated from a large number of household level studies is not being utilised by macro and aggregate models which fail to recognise heterogeneity dynamics and fundamental drivers of change in livestock systems household level studies are not standardised and rarely identify and characterise key drivers and mechanisms for exploiting heterogeneity in policy analysis the paper provides an overview of a set of six papers contained in a special edition which define and address this gap in analytical approaches and identify aspects of the way forward evidence is presented of inconsistencies and practicalities which emphasise the gap but all papers present evidence of integrative progress and list opportunities for accelerating it constraints on the subject matter are outlined and a challenge to livestock policy analysts is made

trade and industrial policy on an uneven playing field the case of the deciduous fruit canning industry in south africa the deciduous fruit canning industry dfci is a resource and labor intensive industry with a high trade ratio it offers the prospect of being a significant source of employment and export earnings for a number of southern hemisphere countries which enjoy a considerable comparative advantage market distortions severely constrain this outcome however most importantly a combination of protection and subsidies in the industrially advanced countries in addition as in other sectors globalization is increasingly associated with processes in which value added activities are located in the major markets of the industrialized countries this paper examines the dfci in south africa and explores the consequences of market distortions and the shifting location of profitable activities for both industrial and trade policy in that country

monotone instrumental variables with an application to the returns to schooling for fifty years econometric analyses of treatment response have made extensive use of instrumental variable iv assumptions holding that mean response is constant across specified subpopulations of a population of interest 2 yet the credibility of mean independence conditions and other iv assumptions has often been a matter of considerable disagreement with much debate about whether some covariate is or is not a valid instrument in an application of interest there is therefore good reason to consider weaker but more credible assumptions to this end we introduce monotone instlumental variable miv assumptions holding that mean response varies weakly monotonically across specified subpopulations we study the identifying power of these miv assumptions and give an empirical application the findings reported here add to the literature developing nonparametric bounds on treatment effects 3 this paper uses the same formal setup as manski 1997 there is a probability space j x2 p of individuals each member j of population j has observable covariates xi e x and a response function yj t y mapping the mutually exclusive and exhaustive treatments t e t into outcomes yj t e y person j has a realized treatment zj e t and a realized outcome y 1 y zi both of which are observable the latent outcomes yj t

food stamps and food insecurity what can be learned in the presence of nonclassical measurement error policymakers have been puzzled to observe that food stamp households appear more likely to be food insecure than observationally similar eligible nonparticipating households we reexamine this issue allowing for nonclassical reporting errors in food stamp participation and food insecurity extending the literature on partially identified parameters we introduce a nonparametric framework that makes transparent what can be known about conditional probabilities when a binary outcome and conditioning variable are both subject to nonclassical measurement error we find that the food insecurity paradox hinges on assumptions about the data that are not supported by the previous food stamp participation literature

bounds on average and quantile treatment effects of job corps training on wages we review and extend nonparametric partial identification results for average and quantile treatment effects in the presence of sample selection these methods are applied to assessing the wage effects of job corps united states largest job training program targeting disadvantaged youth excluding hispanics our estimates suggest positive program effects on wages both at the mean and throughout the wage distribution across the demographic groups analyzed the statistically significant estimated average and quantile treatment effects are bounded between 4 6 and 12 percent and 2 7 and 14 percent respectively we also document that the program s wage effects vary across quantiles and demographic groups

shrewd crude or simply deluded comovement and the internet stock phenomenon we show that i return comovement among internet stocks during the late 1990s and early 2000 was not exceedingly high ii there was substantial consistency in the manner by which investors distinguished among internet stocks and iii high comovement is most common during periods of price erosion these results cast doubt on the view that the extraordinary appreciation of internet stocks was due to the crude classification of all such stocks as members of a hot category

nonparametric estimation of labor supply and demand factors this article derives sharp bounds on labor supply and demand shift variables within a nonparametric simultaneous equations model using only observations of the intersection of upward sloping supply curves and downward sloping demand curves furthermore i demonstrate that these bounds tighten with the imposition of plausible assumptions on the distribution of the disturbance terms using katz and murphy s 1992 panel data on wages and labor inputs i estimate these bounds and assess the supply and demand factors that determine changes within male female wage differentials and the college wage premium

heterogeneous beliefs and the effect of replicatable options on asset prices we present two ways in which trading in a replicatable option can affect the price process of the underlying asset in the first situation trading an option that each investor views as pay off redundant breaks a non fully revealing equilibrium that exists when the option market is absent the second situation involves a market that is dynamically complete without options but in which introducing an option market allows self confirming conjectures of additional uncertainty about the future price of the underlying asset heterogeneous beliefs play important though different roles in both situations article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

are ols estimates of the return to schooling biased downward another look the authors examine evidence on bias in ols estimates of the economic return to schooling to study omitted ability bias they use test scores available in the national longitudinal survey of youth as proxies for ability allowing for measurement error in these test scores the authors also explore biases from the endogeneity of schooling or experience or measurement error in these variables in their data ols estimation including test scores appears to be appropriate and indicates an upward bias of roughly 40 percent in the ols estimate ignoring ability this contrasts with evidence from other recent research using different statistical experiments to purge schooling of its correlation with the wage equation error copyright 1995 by mit press

two step estimation and inference with possibly many included covariates we study the implications of including many covariates in a first step estimate entering a two step estimation procedure we find that a first order bias emerges when the number of included covariates is large relative to the square root of sample size rendering standard inference procedures invalid we show that the jackknife is able to estimate this many covariates bias consistently thereby delivering a new automatic bias corrected two step point estimator the jackknife also consistently estimates the standard error of the original two step point estimator for inference we develop a valid post bias correction bootstrap approximation that accounts for the additional variability introduced by the jackknife bias correction we find that the jackknife bias corrected point estimator and the bootstrap post bias correction inference perform excellent in simulations offering important improvements over conventional two step point estimators and inference procedures which are not robust to including many covariates we apply our results to an array of distinct treatment effect policy evaluation and other applied microeconomics settings in particular we discuss production function and marginal treatment effect estimation in detail

unobserved ability and the return to schooling in the empirical literature it is customary to estimate the return to schooling by ordinary least squares ols or instrumental variable iv techniques 2 the choice of ols is justified only if realized schooling and unobserved labor market ability are uncorrelated if not ols estimates suffer the ability bias and other estimation methods such as iv may be used the volume of work devoted to the return to schooling is a good indication of the importance of this topic as perceived by economists 3 frequently instrumental variables iv techniques are applied in a context where the instrument is only weakly correlated with schooling attainments staiger and stock 1997 as a consequence the validity of very high returns to schooling reported in a simple regression framework should be seriously questioned see manski and pepper 2000 4 when iv techniques are chosen the log wage regression is usually assumed to be linear in schooling however there is no obvious reason to presume that the local returns to schooling are independent of grade level indeed heterogeneity in any component of schooling choices subjective discount rates ability or specific taste for schooling will lead to improper inference if the local returns are erroneously assumed to be constant as individuals with lower taste for schooling tend to stop school earlier ols or iv estimates of the return to schooling which impose equality between local and average returns at all levels of schooling will be strongly affected by the relative frequencies of individuals with high and low taste for schooling more precisely if there are large differences in local returns between various grade levels the ols estimate measuring an average log wage increment per year of schooling will tend to be biased toward the co editor and three anonymous referees for comments and suggestions on this version or earlier versions belzil thanks the social sciences and humanities research council of canada for generous funding the usual disclaimer applies 2 to use the same terminology as in the reduced form literature the return local to schooling refers to the percentage wage increase per additional year of schooling in the paper the terms local and marginal returns may be used interchangeably the average return refers to the slope of the straight line between the intercept and the expected log wage at a given number of years of schooling 3 a world wide web survey of the most recent literature indicates that since 1970 more than 200 published articles or working papers set in a reduced form have been devoted to the estimation of the return to schooling or surrounding issues very often studies based on iv methods conclude that the returns to schooling can be between 20 and 40 above the ols estimates reported estimates around 15 per year for the us are not uncommon although standard errors are typically very high see card 1999 for a survey 4 manski and pepper 2000 obtain upper bound estimates of the return to schooling from a sample taken from the nlsy their results cast doubts on the high returns reported in the literature

coordinating investment production and subcontracting we value the option of subcontracting to improve financial performance and system coordination by analyzing a competitive stochastic investment game with recourse the manufacturer and subcontractor decide separately on their capacity investment levels then demand uncertainty is resolved and both parties have the option to subcontract when deciding on their production and sales we analyze and present outsourcing conditions for three contract types 1 price only contracts where an ex ante transfer price is set for each unit supplied by the subcontractor 2 incomplete contracts where both parties negotiate over the subcontracting transfer and 3 state dependent price only and incomplete contracts for which we show an equivalence result while subcontracting with these three contract types can coordinate production decisions in the supply system only state dependent contracts can eliminate all decentralization costs and coordinate capacity investment decisions the minimally sufficient price only contract that coordinates our supply chain specifies transfer prices for a small number 6 in our model of contingent scenarios our game theoretic model allows the analysis of the role of transfer prices and of the bargaining power of buyer and supplier we find that sometimes firms may be better off leaving some contract parameters unspecified ex ante and agreeing to negotiate ex post also a price focused strategy for managing subcontractors can backfire because a lower transfer price may decrease the manufacturer s profit finally as with financial options the option value of subcontracting increases as markets are more volatile or more negatively correlated

partial identification methods for evaluating food assistance programs a case study of the causal impact of snap on food insecurity we illustrate how partial identification methods can be used to provide credible inferences on the causal impacts of food assistance programs focusing on the impact that the supplemental nutrition assistance program snap formerly known as the food stamp program has on food insecurity among households with children recent research applies these methods to address two key issues confounding identification missing counterfactuals and nonrandomly misclassified treatment status in this paper we illustrate and extend the recent literature by using data from the survey of income and program participation sipp to study the robustness of prior conclusions the sipp confers important advantages the detailed information about income and eligibility allows us to apply a modified discontinuity design to sharpen inferences and the panel nature allows us to reduce uncertainty about true participation status we find that snap reduces the prevalence of food insecurity in households with children by at least six percentage points

short term variations and long term dynamics in commodity prices in this article we develop a two factor model of commodity prices that allows meanreversion in short term prices and uncertainty in the equilibrium level to which prices revert although these two factors are not directly observable they may be estimated from spot and futures prices intuitively movements in prices for long maturity futures contracts provide information about the equilibrium price level and differences between the prices for the short and long term contracts provide information about short term variations in prices we show that although this model does not explicitly consider changes in convenience yields over time this short term long term model is equivalent to the stochastic convenience yield model developed in gibson and schwartz 1990 we estimate the parameters of the model using prices for oil futures contracts and apply the model to some hypothetical oil linked assets to demonstrate its use and some of its advantages over the gibson schwartz model

the effect of male migration on employment patterns of women in nepal what is the impact of male migration on the labor market behavior of women in nepal the instrumental variable full information maximum likelihood method is applied to data from the 2004 nepal household survey to account for unobserved factors that could simultaneously affect men s decision to migrate and women s decision to participate in the labor market the results indicate that male migration has a negative impact on the level of the labor market participation by women in the migrant sending household there is evidence of substantial heterogeneity based on both observable and unobservable characteristics in the impact of male migration the findings highlight the important gender dimension of the impact of predominantly male migration on the well being of sending households strategies for economic development in nepal should take into account such gender aspects of the migration dynamics

rational markets yes or no the affirmative case with the recent flurry of articles declaiming the death of the rational market hypothesis it is well to pause and recall the very sound reasons this hypothesis was once so widely accepted at least in academic circles although academic models often assume that all investors are rational this assumption is clearly an expository device not to be taken seriously what is in contention is whether markets are rational in the sense that prices are set as if all investors are rational even if markets are not rational in this sense abnormal profit opportunities still may not exist in that case markets may be said to be minimally rational i maintain that not only are developed financial markets minimally rational they are with two qualifications rational i contend that realistically market rationality needs to be defined so as to allow investors to be uncertain about the characteristics of other investors in the market i also argue that investor irrationality to the extent that it affects prices is particularly likely to be manifest through overconfidence which in turn is likely to make the market hyper rational to illustrate the article reexamines some of the most serious historical evidence against market rationality

a dynamic analysis of educational attainment occupational choices and job search this article examines career choices using a dynamic structural model that nests a job search model within a human capital model of occupational and educational choices wage growth occurs in the model because workers move between firms and occupations as they search for suitable job matches and because workers endogenously accumulate firm and occupation specific human capital simulations performed using the estimated model reveal that both self selection in occupational choices and mobility between firms account for a much larger share of total earnings and utility than the combined effects of firm and occupation specific human capital

the effect of sibling sex composition on women s education and earnings this paper documents the impact of siblings on the education of men and women born in the united states between 1920 and 1965 we examine the effect of the number and sex composition of a boy or girl s siblings on that child s educational attainment we find that throughout the century women s educational choices have been systematically affected by the sex composition of her siblings and that men s choices have not women raised only with brothers have received on average significantly more education than women raised with any sisters controlling for household size since sibling sex composition affects women s educational attainment and plausibly may be unrelated to other determinants of earnings it may provide a useful instrument for education in earnings functions for women our results suggest that standard estimates significantly underestimate the return to schooling for women

real options approach based demand forecasting method for a range of products with highly volatile and correlated demand to achieve a competitive edge needed for marketing highly competitive products modern enterprises have actively sought to provide the marketplace with an expansive range of products with high random volatility of demand and correlations between demands of product consequently traditional forecasting methods for separately forecasting demand for these products are likely to yield significant deviations therefore this study develops a real options approach based forecasting model to accurately predict future demand for a given range of products with highly volatile and correlated demand additionally this study also proposes using monte carlo simulation to solve the demand forecasting model the real options approach associated with monte carlo simulation not only deals effectively with random variation involving a particular demand stochastic diffusion process but can handle the correlations in product demand

real option value and random jumps application of a simulation model this article studies how sensitive real option valuations are to incorrect assumptions about the stochastic process followed by the state variables we design a valuation model which combines monte carlo simulation and dynamic programming and provides an appropriate framework to evaluate the effect of estimation errors on both the value of real options and their critical frontier although the model is flexible enough to value american type options contingent on a wide range of stochastic processes we focus on the analysis of the effect of stochastic jumps we apply our model to the valuation of an investment in the car parts industry documented in previous literature our results clearly show that underestimating this type of jumps might lead to substantial misjudgements in a firm s decision making processes for instance it may lead to profitable projects being rejected when jump diffusion is low or negative expanded net present value projects being accepted

discussion of valuation of internet stocks an ipo perspective the discussion reviews bms s analysis of how summary financial data from the ipo prospectus are associated with the ipo offer price and the initial market price the authors focus on whether the value drivers associated with these prices differ between internet and non internet firms and between the offer price and the day one ending price they conclude that there are differences in the value drivers used to value internet versus non internet firms and further differences in the value drivers used to arrive at the offer price and the day one ending price the review raises several concerns about these conclusions one concern is that the reader confronts a challenge in trying to interpret the differences between the value drivers affecting the offer price and the day one ending price the review discusses two factors for the reader to consider before interpreting these differences the review also critiques the paper s avoidance of disaggregated financial statement information in the value driver analyses and details several research design concerns

forecasting marketing mix responsiveness for new products abstract before a new product launch marketers need to infer how demand will respond to various levels of marketing mix variables to set an appropriate marketing plan a critical challenge in estimating marketing mix responsiveness from historical data is that the observed decisions were affected by private information possessed by managers about the heterogeneous effects of marketing mix variables on sales the authors refer to this as the slope endogeneity problem such endogeneity differs from the intercept endogeneity problem which has been widely acknowledged in the literature to correct for the slope endogeneity bias the authors develop a conceptually simple control function approach that is amenable to multiple endogenous variables and marketing mix carryover effects the method is applied to forecasting advertising responsiveness in the u s dvd market the results suggest that advertising responsiveness varies substantially across dvd titles and that estimated marketing mix elasticities w

the effects of job corps training on wages of adolescents and young adults previous evaluations of job corps document disparate effects on the earnings of adolescents aged 16 19 and young adults aged 20 24 these are conjectured to be due to differential human capital accumulation within the program between these groups if correct the effect of the program on wages should be larger than that on earnings since wages more accurately reflect human capital we estimate bounds on average and quantile treatment effects of job corps on wages and find that the relative effects on both outcomes are similar casting some doubt on the conjecture that human capital is driving the disparate effects

information distortion in a supply chain the bullwhip effect this article originally appeared in management science april 1997 volume 43 number 4 pp 546 558 published by the institute of management sciences consider a series of companies in a supply chain each of whom orders from its immediate upstream member in this setting inbound orders from a downstream member serve as a valuable informational input to upstream production and inventory decisions this paper claims that the information transferred in the form of orders tends to be distorted and can misguide upstream members in their inventory and production decisions in particular the variance of orders may be larger than that of sales and distortion tends to increase as one moves upstream a phenomenon termed bullwhip effect this paper analyzes four sources of the bullwhip effect demand signal processing rationing game order batching and price variations actions that can be taken to mitigate the detrimental impact of this distortion are also discussed

identification and asymptotic approximations three examples of progress in econometric theory in empirical economics the size and quality of datasets and computational power has grown substantially along with the size and complexity of the econometric models and the population parameters of interest with more and better data it is natural to expect to be able to answer more subtle questions about population relationships and to pay more attention to the consequences of misspecification of the model for the empirical conclusions much of the recent work in econometrics has emphasized two themes the first is the fragility of statistical identification the other related theme involves the way economists make large sample approximations to the distributions of estimators and test statistics i will discuss how these issues of identification and alternative asymptotic approximations have been studied in three research areas analysis of linear endogenous regressor models with many and or weak instruments nonparametric models with endogenous regressors and estimation of partially identified parameters these areas offer good examples of the progress that has been made in econometrics

rational pricing of internet companies we apply real options theory and capital budgeting techniques to the problem of valuing an internet company we formulate the model in continuous time form a discrete time approximation estimate the model parameters solve the model by simulation and then perform sensitivity analysis we report that depending on the parameters chosen the value of an internet stock may be rational if growth rates in revenues are high enough even with a real chance that a company may go bankrupt if the initial growth rates are sufficiently high and if this growth rate contains enough volatility over time then valuations can reach a level that would otherwise appear dramatically high in addition the valuation is highly sensitive to initial conditions and exact specification of the parameters which is consistent with observations that the returns of internet stocks have been strikingly volatile

returns to schooling implicit discount rates and black white wage differentials a simple econometric model of investment in schooling is developed and estimated the measure of individual discount rates implicit in their educational investment decisions suggests no difference between individuals from different socioeconomic backgrounds differences in individual speeds of educational attainment which do vary with background explain most of the variation in levels of attainment that is attributable to family background

an analysis of the implications for stock and futures price volatility of program trading and dynamic hedging strategies the notion that a real security is redundant when it can be synthesized by a dynamic trading strategy ignores the informati onal role of real securities markets portfolio insurance uses a dyna mic strategy to synthesize a european put the absence of trading in an appropriate real put option prevents the transmittal of informatio n to market participants about the future price volatility associated with current dynamic hedging strategies less information is transmi tted to potential liquidity providers it will therefore be more di fficult for the market to absorb the trades implied by the dynamic he dging strategies and the stocks future price volatility will rise copyright 1988 by the university of chicago

estimates of the economic returns to schooling from a new sample of twins this paper uses a new survey to contrast the wages of genetically identical twins with different schooling levels multiple measurements of schooling levels were also collected to assess the effect of reporting error on the estimated economic returns to schooling the data indicate that omitted ability variables do not bias the estimated return to schooling upward but that measurement error does bias it downward adjustment for measurement error indicates that an additional year of schooling increases wages by 12 to 16 percent a higher estimate of the economic returns to schooling than has been previously found copyright 1994 by american economic association

multilateral environmental agreements and the wto addressing many environmental problems requires international cooperation however rules under the world trade organization wto may deter participation in multilateral environmental agreements using a partial identification approach we obtain strictly negative bounds for non oecd countries in the wto era

governance and trade in fresh vegetables the impact of uk supermarkets on the african horticulture industry production of fresh vegetables for export has grown rapidly in a number of countries in sub saharan africa over the last decade this trade brings producers and exporters based in africa together with importers and retailers in europe large retailers in europe play a decisive role in structuring the production and processing of fresh vegetables exported from africa the requirements they specify for cost quality delivery product variety innovation food safety and quality systems help top determine what types of producers and processors are able to gain access to the fresh vegetables chain and the activities they must carry out the control over the fresh vegetables trade exercised by uk supermarkets has clear consequences for inclusion and exclusion of producers and exporters of differing types and for the long term prospects for the fresh vegetables industry in the two major exporting countries studied kenya and zimbabwe

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

international diffusion and intellectual property rights an empirical analysis abstract does a stronger intellectual property rights regime lead to the faster diffusion of new products and technology while there is a presumption that this is the case our analysis of data on the international release patterns of hollywood movies suggests a more complex story although moderate standards of ipr encourage the spread of movies either very weak or very strong property rights tend to slow the speed with which american movies are released abroad this empirical finding is robust to a wide variety of specifications overall it appears that while some recognition of ipr may encourage diffusion very strong ipr may actually retard the speed of diffusion

global value chains labor organization and private social standards lessons from east african cut flower industries summary this article examines the opportunities and challenges that private social standards pose for labor organizations it explores different labor responses to private social standards in east african cut flower industries the analysis incorporates the concept of labor agency in global value chain analysis and reveals how retailer driven chains offer more room for labor organizations to exercise their agency than the traditional cut flower value chains labor organizations have been able to influence social standard setting and implementation and to use standards to further labor representation at production sites however labor organizations ability to seriously challenge the prevailing governance structure of the cut flower value chain appears extremely limited

the valuation and market rationality of internet stock prices this paper provides an analysis of some existing as well as new evidence of the relation between market prices and fundamentals in the internet sector over the period january 1998 to february 2000 appealing to results across a broad class of outcomes we demonstrate a strong circumstantial case against market rationality in particular we investigate i the level of internet stock prices given their underlying fundamentals ii responses of stock prices to information based events and iii the volatility of internet prices we review several potential explanations of these phenomena including one based on heterogeneous beliefs across investors who are subject to short sales constraints we provide a discussion of the empirical evidence supporting this latter explanation copyright 2002 oxford university press

the intergenerational transmission of welfare receipt a nonparametric bounds analysis using a nonparametric bounding method and data from the panel study of income dynamics i examine the effect that growing up in a household that receives aid to families with dependent children af

changes in the distribution of male and female wages accounting for employment composition using bounds this paper examines changes in the distribution of wages using bounds to allow for the impact of nonrandom selection into work we show that worst case bounds can be informative however because employment rates in the united kingdom are often low they are not informative about changes in educational or gender wage differentials thus we explore ways to tighten these bounds using restrictions motivated from economic theory with these assumptions we find convincing evidence of an increase in inequality within education groups changes in educational differentials and increases in the relative wages of women

adoption curves and social interactions this paper considers the observational implications of social influences on adoption decisions for an environment of perfect foresight adopters we argue that social influences can produce two observable effects 1 discontinuities in unconditional adoption curves and 2 pattern reversals in conditional adoption curves in which earlier adoption is found for one group of actors versus another when fundamentals suggest the reverse ordering should occur in turn the presence of either of these features can under weak assumptions be interpreted as evidence of social influences as such these properties are robust implications of social effects jel c40 d01 o33

partially identifying treatment effects with an application to covering the uninsured we extend the nonparametric literature on partially identified probability distributions and use our analytical results to provide sharp bounds on the impact of universal health insurance on provider visits and medical expenditures our approach accounts for uncertainty about the reliability of self reported insurance status as well as uncertainty created by unknown counterfactuals we construct health insurance validation data using detailed information from the medical expenditure panel survey imposing relatively weak nonparametric assumptions we estimate that under universal coverage monthly per capita provider visits and expenditures would rise by less than 8 percent and 16 percent respectively across the nonelderly population

equilibrium open interest abstract this paper analyses what determines an individual investor s risk sharing demand for options and aggregating across investors what the equilibrium demand for options we find that agents trade options to achieve their desired skewness specifically we find that portfolio holdings boil down to a three fund separation theorem that includes a so called skewness portfolio that agents like to attain our analysis indicates also however that the common risk sharing setup used for option demand and pricing is incompatible with a stylized fact about open interest across strikes

the twin instrument fertility and human capital investment twin births are often used as an instrument to address selection of women into fertility however recent work shows selection of women into twin birth such that while ols estimates tend to be downward biased twin iv estimates will tend to be upward biased this is pertinent given the emerging consensus that fertility has limited impacts on women s labour supply or on investments in children using data for developing countries and the united states to estimate the trade off between fertility and children s human capital we demonstrate the nature and size of the bias in the twin iv estimator and estimate bounds on the true parameter

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

shakeouts and market crashes this article provides a microfoundation for the rise in optimism that seems to precede market crashes small young markets are more likely to experience stock price run ups and crashes we use a zeira rob type of model in which demand size is uncertain optimism then grows rationally if traders prior distribution over market size has a decreasing hazard such prior beliefs are appropriate if most new markets are duds and only a few reach a large size the crash occurs when capacity outstrips demand as an illustration for the period 1971 2001 we fit the model to the telecom sector

the formation of cooperatives a game theoretic approach with implications for cooperative finance decision making and stability this paper departs from the traditional organization oriented approach to cooperative analysis it exploits cooperation s functional similarity to vertical integration to examine individuals incentives to form cooperatives a model of formation of a purchasing cooperative is presented and developed as an n person game with the core as a solution concept core existence is examined for both single and multiple cooperative configurations and cooperative finance methods are examined relative to finding core compatible allocation rules the results provide insight into a cooperative s equilibrium output stability decision making financing methods and choice of open or restricted membership

education and earnings in the netherlands an empirical analysis abstract in this paper three models which describe the relation between earnings and education are estimated using one single data set one model is a simple dummy regression model in which the educational variables are exogenous both other models take account of the fact that individuals choose their optimal amount of education and is therefore endogenous in all three models i try to specify the equations in the same way as others have done with other data sets it turns out that in each model important conclusions reached in earlier research are not supported by the empirical findings reported here

agent based spatial models applied to agriculture a simulation tool for technology diffusion resource use changes and policy analysis abstract this paper presents a spatial multi agent programming model which has been developed for assessing policy options in the diffusion of innovations and resource use changes unlike conventional simulation tools used in agricultural economics the model class described here applies a multi agent cellular automata ca approach by using heterogeneous farm household models and capturing their social and spatial interactions explicitly the individual choice of the farm household among available production consumption investment and marketing alternatives is represented in recursive linear programming models adoption constraints are introduced in form of network threshold values that reflect the cumulative effects of experience and observation of peers experiences the model s economic and hydrologic components are tightly connected into a spatial framework the integration of economic and hydrologic processes facilitates the consideration of feedback effects in the use of water for irrigation the simulation runs of the model are carried out with an empirical data set which has been derived from various data sources on an agricultural region in chile simulation results show that agent based spatial modelling constitutes a powerful approach to better understanding processes of innovation and resource use change

treatment effect bounds under monotonicity assumptions an application to swan ganz catheterization in section i we describe each of the resulting bounds when there are no other exogenous covariates that directly affect the outcome we show that if the effect of the treatment is positive and the assumptions of sv hold then the bounds of sv coincide with those of mp that assume a priori that the effect of the treatment is positive if the effect of the treatment is instead negative and the assumptions of sv hold then the bounds of sv coincide with those of mp that assume a priori that the effect of the treatment is negative hence the trade off between the analyses of sv treatment effect bounds under monotonicity assumptions an application to swan ganz catheterization

quantifying value chain analysis in the context of livestock systems in developing countries the analysis of value chains has augmented our knowledge on the complexities inter linkages distributional benefits and institutional arrangements of production and marketing channels in developing countries however the analysis remains relatively qualitative and case specific with limited ability to rank or assess the impact of alternative interventions or to analyze sufficiently the complex market dynamics and feedbacks present in livestock systems this paper offers theoretical and applied insights on ways to improve the analytical rigor of the value chain methodology that combines both qualitative and quantitative approaches

nonparametric bounds on treatment effects assume that each member of a population is characterized by values for the variables ya yb z x here x is a vector describing a person and z is a binary variable indicating which of two treatments this person receives the treatments are labelled a and b the variables ya and yb are scalar measures of the outcomes of the two treatments for example a cancer patient might be treated by a drug therapy or b surgery the relevant outcome y might be life span following treatment an unemployed worker might be given a vocational training or b job search assistance here the relevant outcome might be labor force status following treatment assume that a random sample is drawn and that one observes the realizations of z x and of the outcome under the treatment received thus ya is observed if treatment a is received but is a latent variable if treatment b is received similarly yb is either observed or latent suppose that one wants to learn the difference in expected outcome if all persons with attributes x were assigned to treatment a or b this treatment effect is

omitted ability bias and the increase in the return to schooling over the 1980s there were sharp increases in the return to schooling estimated with conventional wage regressions we explore whether the relationship between ability and schooling changed over this period in ways that would have increased the schooling coefficient in these regressions our empirical results reject the hypothesis that an increase in the bias of the schooling coefficient due to a change in the relationship between ability and schooling has contributed to observed increases in the return to schooling we also find that the increase in the schooling return has occurred for workers with relatively high levels of academic ability

learning from global buyers an increasing number of developing countries engage in contract manufacturing for a decreasing number of global buyers this constellation characterises many labour intensive export sectors the positioning of developing country enterprises in such buyer driven chains is central to research concerned with identifying the winners and losers from globalisation this study contributes to this debate by seeking answers to two questions first what can researchers learn from global buyers about the relative strengths and weaknesses of developing country producers second what can these producers learn from global buyers and what circumstances facilitate or constrain such learning