a generalized measure of farm specific technical efficiency single measures of farm specific technical efficiency over time are calculated for rice farms in central luzon the philippines from the residuals of a stochastic frontier production function panel data from the international rice research institute s periodic loop survey are used results show a narrow range of efficiency between 84 and 95 across the twenty two farms so that there is limited scope for increasing output by resource reallocation a comparison is made with measures of technical efficiency using traditional covariance analysis

modern rice technology and regional wage differentials in the philippines abstract fear has been widely expressed that the modern rice varieties have created large disparities in regional income distribution as the productivity gap between favorable and unfavorable rice production environments widened due to differential technology adoption throughout south and southeast asia over the last two decades technology affects the income of farm population directly through its effects on productivity and factor use and indirectly through its effect on factor prices in particular the ultimate distributional impact of modern varieties will critically depend on the interregional labor market adjustments through migration in response to regional wage differentials created by the differential technology adoption since labor is the main resource of the majority of the rural population we studied favorable and unfavorable rice growing villages in the philippines and found that adoption of modern varieties during the 1970s was positively related to population growth rate contrary to popular belief no association was observed between wage rates and adoption of modern varieties as of 1986 these findings support the hypothesis that the differential adoption of modern rice varieties induced interregional labor migration toward equalization of wage income across different production environments

the role of permanent income and demographics in black white differences in wealth we explore the extent to which the large race gap in wealth can be explained with properly constructed income and demographic variables in some instances we explain the entire wealth gap with income and demographics provided that we estimate the wealth model on a sample of whites however we typically explain a much smaller fraction when we estimate the wealth model on a black sample using sibling fixed effects models to control for intergenerational transfers and the effects of adverse history we find that these factors are not likely to account for the lower explanatory power of the black wealth models our analysis of growth models of wealth suggests that differences in savings behavior and or rates of return play an important role

arbitrage and existence of equilibrium in infinite asset markets this paper develops a framework for a general equilibrium analysis of asset markets when the number of assets is infinite such markets have been studied in financial economics in the context of asset pricing theories a distinctive feature of an equilibrium model of asset markets is that investors portfolio choice sets are typically not bounded below we prove that an equilibrium exists under a condition that markets are arbitrage free the markets are arbitrage free if there is a price system under which no investor has an arbitrage opportunity the concept of an arbitrage opportunity used in this paper differs from the standard concept on an arbitrage portfolio in financial markets which is a portfolio that guarantees a non negative payoff in every event a positive payoff in some event and has zero price we provide an extensive discussion of concepts of an arbitrage opportunity

portfolio choices of parents and their children as young adults asset accumulation by african american families the portfolio composition decision often is stylized as either a life cycle choice to allocate income to consumption or as a choice along a risk return locus with the locus derived from the underlying market equilibrium of asset returns and prices empirical work on household financial behavior has identified large differences in wealth levels and in portfoliocomposition choices of different demographic groups well beyond income and risk tolerance by far the most striking difference in this literature emerges when the population is subdivided by race for example given the strong performance of the u s equity market in the past decade portfolio choices of stocks have been key to wealth building yet africanamerican families have been less likely to have held stocks as of the mid 1980 s and less likely to have become shareholders over the period 1989 1994 erik hurst et al 1998 this paper attempts to resolve this puzzle by examining cross generational influences on current portfolio composition decisions

understanding new zealand s changing income distribution 1983 1998 a semi parametric analysis this paper analyses income distribution changes in new zealand between 1983 and 1998 we use a semi parametric kernel density approach and a range of inequality summary measures to assess the distributional effects of changes in five sets of factors household structure national superannuation old age pension socio demographic attributes employment outcomes and economic returns to such attributes and employment outcomes changes in household structure and attributes are the main factors contributing to the rise in inequality employment changes and changing returns had a more modest impact the results are qualitatively robust to a variety of equivalization income and weighting measures

determinants and consequences of land reform implementation in the philippines abstract unlike the experience of other developing countries land reform in the philippines has been successful in converting many of share tenants to land reform beneficiaries this study indicates that the implementation of land reform is positively associated with yield growth made possible by the adoption of modern seed fertilizer technology a major reason underlying such association is considered to be an increased economic interest of tenants in land reform arising from divergence of rental value of land from leasehold rent and amortization fees prescribed by law

a comparative analysis of the nativity wealth gap this paper investigates the source of the gap in the relative wealth posi tion of immigrant households residing in australia germany and the united states our results indicate that in germany and the united states wealth difierentials are largely the result of disparity in the educational attainment and demographic composition of the native and immigrant populations while income difierentials are relatively unimportant in understanding the nativity wealth gap in contrast the relatively small wealth gap between australian and foreign born households exists because immigrants to australia do not translate their relative educational and demographic advantage into a wealth advantage on balance our results point to substantial cross national disparity in the economic well being of immigrant and native families which is largely consistent with domestic labor markets and the selection policies used to shape the nature of the immigration ow

technology adoption and agricultural price policy market interventions such as price supports or fertilizer subsidies can lead to gains from speeding up adoption of new technologies but the policies distort resource allocation a framework is developed for optimizing policies in light of the adoption allocation trade off based on adoption coefficients and production parameters from third world agriculture levels and duration of policies are estimated sensitivity analyses are performed gains are small at best and may be zero or negative in view of farmer costs of adjustment and deadweight losses from taxes profit technology adoption if new technologies are desirable why not use price supports or input subsidies to encourage faster technology adoption while frequently raised in policy deliberations this question has received little serious analysis particularly neglected has been the conflict or trade off between a gains in output as producers switch from old to new technologies and b the losses from resource use distortions brought about by price policies when output prices are raised or prices of inputs such as fertilizer are lowered the

initial conditions at emancipation the long run effect on black white wealth and earnings inequality abstract black white wealth inequality is much greater than black white earnings inequality in the united states the existing empirical literature has not been able to fully explain the wealth gap this paper investigates how much of current black white income and wealth inequality can be explained by initial conditions at emancipation and nearly 100 years of segregated schools a two sector model with group specific human capital accumulation and school expenditure differences can explain the path of black white convergence in earnings over the past 130 years the model also reproduces the fact that black white wealth ratios remain much lower than black white earnings ratios

potato led growth the macroeconomic effects of technological innovations in bolivian agriculture through the use of a computable general equilibrium model we measure the economy wide effects of improving the production technology of relatively non traded staples potatoes maize import crops wheat and export crops soybeans in bolivia the results of the analysis suggest that technological innovations in the production technology of potatoes would benefit the bolivian economy most we discuss the reasons for the limited effects of technological innovations in tradeable crops

arbitrage bubbles and valuation the standard present value rule of asset pricing may fail in financial markets when infinitely many assets can be traded i provide an example of asset payoffs and prices such that prices are arbitrage free and could be equilibrium prices in frictionless markets using valuation theory methods i show that asset prices can be meaningfully decomposed into a fundamental value and a pricing bubble the fundamental value obeys the present value rule

demographic pressure technological innovation and welfare the case of the agriculture of bangladesh in the early years of its introduction the hyv technology was widely regarded as a technical breakthrough that would bring about rapid agrarian progress and a revolutionary improvement in the standard of living of the farm population three decades later the promise of the new technology remains unfulfilled this article argues that the adoption of the hyv technology in the agriculture of bangladesh was determined mainly by an acute demographic pressure since the non agricultural sectors did not expand sufficiently rapidly there was a tremendous pressure on agriculture to accommodate the additional workforce the imperative to employ a larger workforce and feed a rising population forced the farmers to adopt the labour intensive land augmenting hyv technology the welfare of the farmers did not show any secular increase with the switch to the new technology

green revolution and labour demand in rice farming the case of central luzon 1966 90 while the adoption of modern rice varieties mvs increased labour requirements for crop care and other activities it might have induced the adoption of labour saving technologies thus whether the net impact of mv adoption on labour demand is significantly positive is still debated in the green revolution literature using farm level survey data collected in central luzon from 1966 to 1990 this study estimated simultaneously the labour saving technology adoption and the labour demand functions we found among other things that mvs increased labour demand significantly without inducing the widespread adoption of labour saving technologies

distributional changes in the gender wage gap using panel study of income dynamics psid data the authors analyze changes in wage differentials between white men and women over time and across the entire wage distribution the authors decompose distributional changes in the gender wage gap to assess the contribution of observed characteristics measuring individual productivity they find that the gender wage gap narrowed by 16 at the lowest decile and by less than 5 at the highest decile the decomposition results indicate that changes in the gender wage gap are mainly attributable to changes in educational attainment at the top of the wage distribution with a sizable part due to work history changes at the bottom the findings further reveal that the accuracy of the results depends on the direction in which the decompositions are performed

permanent labour and land tenancy contracts in agrarian economies an integrated analysis extending the existing models of land and labour contracts this study attempts to build a general model of long term agrarian contracts the model implies that where tenancy is an available option the fixed wage permanent labour contract will not be chosen if it is chosen under institutional constraints on tenancy contracts resulting resource allocations will be inefficient empirical relevance of the model is tested on data from the philippines

recent trends in the size distribution of household wealth based on the survey of consumer finances the distribution of wealth in the united states became much more unequal in the 1980s and that trend continued albeit at a slower pace in the 1990s the only households that saw their mean net worth rise in absolute terms between 1983 and 1995 were those in the top 20 percent and the gains were particularly strong for the top one percent all other groups were particularly strong for the top one percent all other groups suffered real wealth losses including the median household and declines were particularly precipitous at the bottom racial disparities widened and young households also lost out over this period

black white wealth inequality is inheritance the reason i introduction on average black americans have less wealth than white americans previous studies of wealth reveal that blacks hold on average between 10 and 25 of the wealth held by whites as reported in terrell 1971 smith 1975 sobol 1979 blau and graham 1990 and wolff 1992 a number of possible explanations for this gap have been suggested particularly differences in income and various socio economic characteristics between black and white households however the average difference in black white household income is much less than the difference in black white household wealth wolff 1992 reports that black household income averaged 63 of white household income in 1989 a ratio which had persisted over the previous twenty years consequently there must be additional factors which explain the greater racial wealth differential recently economists such as blau and graham 1990 and wolff 1992 have surmised that differences in intergenerational transfers might account for much of the unexplained racial difference in wealth we document the large difference in wealth between blacks and whites and then attempt to account for this difference paying particular attention to the effect of inherited wealth a number of investigators have speculated on the possible importance of inheritances in explaining racial differences in wealth in a comment on smith s 1975 analysis of black white wealth differentials vito natrella 1975 noted that smith only explained 25 of the wealth differential through differences in economic variables natrella conjectured that the really significant determinants not included in smith s analysis were prior income inherited wealth and the propensity to save p 370 wolff 1992 suggested that differences in intergenerational transfers provide a plausible explanation of the black white wealth gap but provided no supporting evidence in a recent article blau and graham 1990 attempted to explain racial differences in wealth at the household level as a result of differences in household income location and demographic factors however they found that three quarters of the racial difference in wealth remained unexplained they speculated that racial differences in inheritance and other intergenerational transfers most likely play an important part p 338 in explaining the remaining black white differences in wealth if true this explanation would have important policy implications e g higher rates of inheritance taxation could reduce wealth differences between races ii data in this paper we attempt to empirically verify the hypothesized importance of inheritances in explaining the differences in black and white household wealth our empirical analysis makes use of two data sets which report both household wealth and household inheritances the 1976 national longitudinal surveys of mature men nls76 and the 1989 survey of consumer finances scf89 the nls76 sample was chosen to be representative of the u s male population aged 45 to 59 years old in 1966 with an oversampling of black households our analysis focuses on the sample of 2 019 respondents who survived through 1976 and reported all variables required for our analysis 1 more information about the nls76 can be obtained from the center for human resource research 1992 the scf89 sample was chosen to provide a comprehensive picture of the financial situation of all u s households in 1989 the scf89 oversampled high income households we make use of the complete sample encompassing the multiple imputation procedure employed by researchers at the board of governors of the federal reserve system more information about these data can be obtained in kennickell and shack marquez 1992 since both data sets employ oversampling of particular population segments all sample statistics reported in this paper are sample weighted in the nls76 respondents were asked to report whether they or their spouse had received any girl inheritance or prize such as a lottery or award greater than 1 000

a retrospective view of technological and other changes in philippine rice farming 1965 1982 much has been written about the impact of changes brought about through the introduction of semidwarf fertilizer responsive rice and wheat in asia the terms green revolution and miracle varieties suggest the dramatic effect anticipated from the new biological technology by both its supporters and detractors a great volume of literature has been generated describing the impact of these changes much of that literature is speculative some is theoretical and it would be fair to say much is cast in a tone with negative implications for new technology theoretical analyses necessarily balance simplifying assumptions with the richness of detail needed to capture the effects of technical and other changes while empirical analysis often shows what has happened but sheds little light on why it may have happened a recent review of the empirical literature shows that adoption of modern rice varieties in asia results in increased output has occurred quite evenly among farmers of all size groups and has resulted in modest increases in the use of labor per hectare of rice produced some empirical studies contrast areas that have adopted the technology with areas that have not thereby making the often false implicit assumption that all factors other than those specifically studied were similar other empirical studies concentrate on high adoption areas and use recall to infer how the introduction of technology may have changed variables of interest 2 there are a few pioneer studies available that contrast areas before and after the general adoption of specified technologies 3 this paper is a summary of ongoing research that provides data of the latter type researchers at the international rice research institute irri have monitored two sets of philippine rice producers for over 15 years during that period new rice technology was introduced and was

effect of modern rice varieties and irrigation on household income distribution in nepalese villages abstract since high yielding modern rice varieties mvs are adopted only in favorable production environments significant regional productivity differentials have emerged in nepal this study explores the distributional consequences of such differential mv adoption based on an intensive survey of favorable and unfavorable villages we found that mv adoption increased returns to land but decreased family labor earnings from rice production as it facilitated the substitution of hired for family labor as a result the differential mv adoption did not significantly worsen the household income distribution according to the results of the counterfactual gini decomposition analysis

gender differences in wealth at retirement recent economic trends like the growing prevalence of defined contribution retirement plans have made individuals increasingly responsible for their own financial security financial security greatly depends on the ability to accumulate adequate wealth edward wolff 1998 wealth can be a significant source of retirement income for individuals less and less able to rely on social security and employerprovided defined benefit pension plans one concern in the current economic climate is the persistent gap in wealth between men and women several papers for example lucie schmidt and purvi sevak 2006 have found that the gap is significant even after controlling for individual characteristics this paper contributes to the literature by studying the role of risk preferences in addition to other characteristics specifically it addresses the following research question controlling for other factors do gender differences in risk preferences contribute to the gender wealth gap at retirement the underlying premise is that women are more risk averse than men which is supported by previous research for example robert b barsky et al 1997 a simple theoretical model of household decision making illustrates that retirement wealth is a function of income earned over the lifetime and risk aversion the model is empirically tested using data from the health and retirement study hrs 1 results show that the gender gap in wealth persists even when risk preferences are added to the set of controls thus the unexplained gap remains a cause for concern

the immigrant and native born wage distributions evidence from united states censuses recent studies document a large widening of the immigrant native born mean wage gap since about 1970 a trend that some observers ascribe to post 1965 changes in u s immigration policy these studies are limited however by their exclusive focus on men which ignores important gender differences in the wage gap and by the inadequacy of the mean wage for characterizing the gap when as in recent decades the wage distribution dramatically changes this study of recent immigrants examines changes across the entire wage distribution for both genders the authors find evidence based partly on gender differences that minimum wages strongly influenced the gap a counterfactual analysis also indicates that if recent immigrants in 1970 had faced the 1990 wage structure their wage distribution would have closely resembled that of recent immigrants in 1990 these and other results suggest that the increasing wage gap is linked to changes in the wage structure

new rice technology and comparative advantage in rice production in the philippines the aim of this study is to assess the comparative advantage in rice production in the philippines for the past three decades since 1966 we have found that the country gained sharp improvement in comparative advantage in rice production in 1979 when yield rose remarkably due to the diffusion of pest and disease resistant modern rice beginning in 1986 however the country appears to have slowly lost its comparative advantage due to the decline in rice prices stagnation in rice yield and rising cost of domestic factors by 1990 the country completely lost its comparative advantage in rice production

the wealth of mexican americans this paper analyzes the sources of disparities in the relative wealth position of mexican americans results reveal that unlike the racial wealth gap mexican americans wealth disadvantage is in large part not the result of differences in wealth distributions conditional on the underlying determinants of wealth rather mexican americans wealth disadvantage is attributable to the fact that these families have more young children and heads who are younger mexican americans low educational attainment also has a direct effect in producing a wealth gap relative to other ethnic groups even after differences in income are taken into account income differentials are important but do not play the primary role in explaining the gap in median net worth finally geographic concentration is generally unimportant but does contribute to narrowing the wealth gap between wealthy mexican americans and their white and black counterparts

pesticides productivity and farmer health a philippine case study health is recognized as one of the most important components of the human capital of rural people in developing countries there is a growing body of literature showing the productivity effects of health associated with nutrition e g bliss and stern 1978 strauss 1986 deolalikar 1988 pitt rosenzweig and hassan 1990 in this literature the productivity effects of health are inferred either by correlating health indicators with wages or by including health indicators in an agricultural production function the human capital literature also has demonstrated that farmer education plays an important role in the allocative and technical efficiency of farmers welch 1970 schultz 1975

black white differences in wealth and asset composition using data from the 1976 and 1978 national longitudinal surveys of young men and young women this study examines racial differences in the magnitude and composition of wealth and the reasons for them on average young black families hold 18 percent of the wealth of young white families and hold their wealth in proportionately different forms even after controlling for racial differences in income and other demographic factors as much as three quarters of the wealth gap remains unexplained we speculate on the causes for this concluding that racial differences in intergenerational transfers and to a lesser extent barriers to the accumulation of business and home equity most likely play a role

arbitrage martingales and bubbles abstract viability of security prices implies linear valuation of payoffs but if there exist an infinite number of securities or trading dates does not imply the existence of a risk neutral probability since countable additivity may fail an example is given

on the decomposition of wage differentials the often used method for decomposing wage differentials into human capital and discrimination components is reformulated so that both t he disadvantage or cost discrimination it imposes on a black or minority wage earner and the advantage or benefit it bestows on a white or majority wage earner can be estimated copyright 1988 by mit press

why do mexican americans earn low wages using current population survey data from november 1979 and 1989 i find that mexican americans earn low wages primarily because they possess less human capital than other workers not because they

general equilibrium wariness and efficient bubbles abstract wary consumers overlook gains but not losses in remote sets of dates or states as preferences are upper but not lower mackey semi continuous bewley s 1972 4 result on existence of equilibrium whose prices are not necessarily countably additive holds wariness is related to lack of myopia and to ambiguity aversion and therefore to bewley s 1986 6 work on knightian uncertainty wary infinite lived agents have weaker transversality conditions allowing them to be creditors at infinity and for bubbles to occur in positive net supply assets completing the markets there are efficient allocations that can only be implemented with asset bubbles

bubbles and charges the definitions of fundamental value and speculative bubbles that are standard in macroeconomics and finance are given formal representations as the countably additive part and the purely finitely additive part a measure and a pure charge respectively of the supporting price system when the commodity space is lx examples illustrate that rational bubbles can occur in standard general equilibrium models with complete markets and a finite number of agents even in the absence of uncertainty consider an economy which includes securities or capital goods which are claims to cash flows over countably infinite time and also includes markets for all goods conduct the following thought experiment for each security add the present value of the first n elements of the cash flow and take the limit as n gets large this limit represents the fundamental value of the security the difference if any between the price of the security and its fundamental value is termed a speculative bubble this use of the terms fundamental and speculative bubble is we believe one of those that are generally accepted blanchard and fischer 1989 pp 218 221 for example used the terms precisely in this way yet confusion persists about what factors generate bubbles fads and irrationality have always figured prominently and the hypothesis that these factors are important has gained some empirical support from the literature on asset price volatility another bubbleproducing factor is the structure of information in the market in a partialequilibrium setting allen and gorton 1988 showed that rational bubbles can exist with a finite number of agents who have asymmetric information although fads and asymmetric information can undeniably produce bubbles here we focus exclusively on the phenomenon of speculative bubbles in general equilibrium models with optimizing agents rational expectations and symmetric information an important source of confusion we believe is that the term fundamental is used in connection with sunspot equilibria as well as bubble equilibria a sunspot equilibrium is one in which prices and allocations depend on irrelevant sunspots as well as exogenous variations in fundamentals preferences technology and endowments bubbles on this usage reflect the effect of extrinsic uncertainty on equilibrium prices and allocations this use of the term fundamental in connec

existence of equilibrium in capm abstract in the mean variance capital asset pricing model capm non monotonicity of preferences may lead to satiation and short selling as well as satiation may lead to non existence of equilibrium this paper identifies several sets of sufficient conditions for equilibrium to exist the nature of the central conditions is to impose bounds on the investors degree of risk aversion as measured by the marginal rate of substitution between mean and standard deviation of return these bounds do not need to hold globally but only in a relevant range of portfolios or combinations of mean and standard deviation