natural resource prices will they ever turn up abstract natural resource theory predicts that natural resource rents should increase over time however technical progress in resource extraction environmental constraints or great natural abundance could result in stagnant or declining product prices thus there is no theoretical reason to believe that product prices will rise in the near future the prediction of product prices by time series methods is shown to depend critically upon whether the series are modeled as difference or trend stationary dickey fuller and lagrange multiplier tests are used to show that the series are difference stationary long and short sample series are tested trend stationary modeling strongly predicts rising resource prices the result from difference stationary modeling is that there is only a weak supposition that natural resource prices will rise

the impact of agricultural research in africa aggregate and case study evidence abstract this paper presents case study results and aggregate data to evaluate the impact of research in african agriculture of 32 case studies all but eight report annual returns over 20 and many are far higher with most gains arising in the late 1980s and 1990s spurred by policy reforms and changing incentives these innovations have led to sustained growth in aggregate cereal crop yields since 1985 africa s belated green revolution is based on new varieties often with early maturation for drought escape complemented by new management techniques typically labor intensive efforts to conserve soil moisture and build soil fertility

from physical to human capital accumulation inequality and the process of development this paper develops a growth theory that captures the replacement of physical capital accumulation by human capital accumulation as a prime engine of growth along the process of development it argues that the positive impact of inequality on the growth process was reversed in this process in early stages of the industrial revolution when physical capital accumulation was the prime source of growth inequality stimulated development by channelling resources towards individuals with a higher propensity to save as human capital emerged as a growth engine equality alleviated adverse effects of credit constraints on human capital accumulation stimulating the growth process this research develops a growth theory that captures the endogenous replacement of physical capital accumulation by human capital accumulation as a prime engine of economic growth in the transition from the industrial revolution to modern growth the proposed theory offers a unified account for the effect of income inequality on the growth process during this transition it argues that the replacement of physical capital accumulation by human capital accumulation as a prime engine of economic growth changed the qualitative impact of inequality on the process of development in the early stages of the industrial revolution when physical capital accumulation was the prime source of economic growth inequality enhanced the process of development by channelling resources towards individuals whose marginal propensity to save is higher in the later stages of the transition to modern growth as human capital emerged as a prime engine of economic growth equality alleviated the adverse effect of credit constraints on human capital accumulation and stimulated the growth process the proposed theory unifies two fundamental approaches regarding the effect of income distribution on the process of development the classical approach and the credit market imperfection approach 1 the classical approach was originated by smith 1776 and was further interpreted and developed by keynes 1920 lewis 1954 kaldor 1957 and bourguignon 1981 according to this approach saving rates are an increasing function of wealth and inequality therefore channels resources towards individuals whose marginal propensity to save 1 the socio political economy approach provides an alternative mechanism equality diminishes the tendency for socio political instability or distortionary redistribution and hence it stimulates investment and economic growth see the comprehensive survey of benabou 1996b

the impact of integrated aquaculture agriculture on small scale farms in southern malawi sustainable agricultural intensification is an urgent challenge for sub saharan africa one potential solution is to rely on local farmers knowledge for improved management of diverse on farm resources and integration among various farm enterprises in this article we analyze the farm level impact of one recent example namely the integrated aquaculture agriculture iaa technologies that have been developed and disseminated in a participatory manner in malawi based on a 2004 survey of 315 respondents 166 adopters and 149 nonadopters we test the hypothesis that adoption of iaa is associated with improved farm productivity and more efficient use of resources estimating a technical inefficiency function shows that iaa farms were significantly more efficient compared to nonadopters iaa farms also had higher total factor productivity higher farm income per hectare and higher returns to family labor

why might the rich be indifferent to income growth of their own countries abstract the paper shows using empirical evidence from more than 100 countries household surveys that income gains that the rich can realize through a more unequal distribution are often much larger than the realistic gains from a distribution neutral growth the rich are thus more likely to support policies that increase inequality than be concerned about income growth of their countries

tests of a rational theory of the size of government in many countries the political party holding power changes more frequently than the trend growth rates in government spending and taxes shifts of political power are often preceded by rhetoric about meeting needs or cutting taxes which post election performances rarely match yet changes in the size of government up and down occur on average the size of government measured by the share of taxes or spending to output has increased in many countries during the past century but changes in size occur at diffrent rates and at times the relative size of government declines

input subsidy programs in sub saharan africa a synthesis of recent evidence input subsidy programs have once again become a major plank of agricultural development strategies in africa ten african governments spend roughly us 1 billion annually on input subsidy programs isps amounting to 28 6 of their public expenditures on agriculture this article reviews the microlevel evidence on isps undertaken since the mid 2000s we examine the characteristics of subsidy beneficiaries crop response rates to fertilizer application and their influence on the performance of subsidy programs the impacts of subsidy programs on national fertilizer use and the development of commercial input distribution systems and finally the impact of isps on food price levels and poverty rates the weight of the evidence indicates that the costs of the programs generally outweigh their benefits findings from other developing areas with a higher proportion of crop area under irrigation and with lower fertilizer prices factors that should provide higher returns to fertilizer subsidies than in africa indicate that at least a partial reallocation of expenditures from fertilizer subsidies to r d and infrastructure would provide higher returns to agricultural growth and poverty reduction however because isps enable governments to demonstrate tangible support to constituents they are likely to remain on the african landscape for the foreseeable future hence the study identifies ways in which benefits can be enhanced through changes in implementation modalities and complementary investments within a holistic agricultural intensification strategy among the most important of these are efforts to reduce the crowding out of commercial fertilizer distribution systems and programs to improve soil fertility to enable farmers to use fertilizer more efficiently the challenges associated with achieving these gains are likely to be formidable

the impact of research led agricultural productivity growth on poverty reduction in africa asia and latin america abstract twenty percent of the world s population or 1 2 billion live on less than 1 per day 70 of these are rural and 90 are in asia and sub saharan africa research led technological change in agriculture generates sufficient productivity growth to give high rates of return in africa and asia and has a substantial impact on poverty currently reducing this number by 27 million per annum whereas productivity growth in industry and services has no impact the per capita cost of poverty reduction by means of agricultural research expenditures in africa is 144 and in asia 180 or 50 cents per day but this is covered by output growth by contrast the per capita cost for the richer countries of latin america is over 11 000

valuing mineral reserves when capacity constrains production abstract we add a capacity constraint and heterogeneous reserves to the hotelling valuation principle this produces a more general version of the principle that is more consistent with empirical valuations while retaining the underlying relationship between net price and reserve value

econometric issues in the analysis of contagion this paper presents a canonical econometric model of contagion and investigates the conditions under which contagion can be distinguished from inter dependence in a two country market set up it is shown that for a range of fundamentals the solution is not unique and for sufficiently large values of the contagion coefficients it has interesting bifurcation properties with bimodal density functions the extension of the model to herding behaviour is also briefly discussed to identify contagion effects in the presence of inter dependencies the equations for the individual markets or countries must contain country market specific forcing variables this sheds doubt on the general validity of the correlation based tests of contagions recently proposed in the literature which do not involve any country market specific fundamentals finally we show that ignoring inter dependence can introduce an upward bias in the estimate of the contagion coefficient and using monte carlo experiments we further show that this bias could be substantial

returns from research in economies with policy distortions hybrid sorghum in sudan conventional estimates of the economic return to agricultural research use market prices for the values of products and inputs on this basis economic rates of return are typically well above the cost of capital suggesting that more investment in research would be socially desirable but these estimates may be incorrect if as is often the case market prices are distorted by market failures or government policies and hence do not reflect social values this paper presents a simple partial equilibrium methodology with which to improve the measurement of social returns to research by taking account of multiple distortions in the market prices of products inputs and foreign exchange the method also takes account of variation in domestic and world prices making a product tradable in some years and nontradable in others the method is applied to the case of hageen dura 1 hd 1 sub saharan africa s first commercially successful hybrid sorghum hd 1 was released in the sudan in 1983 from the start of research in 1979 to 1992 the hd 1 breeding program had an estimated irr of 97 when all major policies in the sorghum market the fertilizer market and the exchange rate are taken into account the high rate of return to hd 1 research was due to the program s low cost and rapid payoff pointing to the potential value of small adaptive research programs taking full advantage of foreign technology and genetic material to produce locally appropriate crosses in a short period of time even in the highly distorted economies of africa such programs can yield very high payoffs

is inequality harmful for growth comment endogenous growth models have reignited interest in institutional and path dependencies in the economic growth process one reason for the interest in endogenous growth models is that they may explain why countries consistently grow at different rates in this vein it has been recently proposed that greater economic inequality reduces future economic growth an important paper in this literature is by torsten persson and guido tabellini 1994 who will be referred to as pt pt s model shows why it is reasonable to expect a negative relationship between inequality and future economic growth moreover their empirical evidence is consistent with their contention if pt s findings are robust to other data sets there would be important policy implications for example they imply that policy makers should not only be concerned with the distributional implications of government policies for political and social reasons but also because income distribution has long run effects on economic growth this indicates that greater u s income inequality since the early 1970 s may have resulted in lower subsequent economic growth however pt s results are somewhat fragile to various specifications suggesting that they should be replicated with different data sets and over different time periods pt p 617 with these implications in mind this study employs data from a panel of u s states to further explore the relationship between economic growth and income inequality in what follows section i summarizes pt s study and discusses how this comment extends their findings the empirical implementation and results in section ii directly examine the link between overall income inequality and growth section iii expands the analysis to alternative measures of income distribution and government policy one emphasis in section iii is the distinction between how the overall income distribution especially at the tails influences economic growth from how the relative well being of the median voter affects economic growth section iv provides some concluding discussion

public education occupational choice and the growth inequality relationship this article develops a dynamic general equilibrium model in which the occupational structure of the economy drives a wedge between the social and private returns to schooling for some workers i study the impacts of alternative allocations of public resources between basic and higher levels of education on enrollments income distribution and growth in particular i illustrate how the growth inequality relationship depends on the tension between two forces 1 the trickle down effects of expenditures on higher education and 2 the positive impacts on secondary enrollments generated by high quality basic education and reduced parental inequality

using evidence of household income diversification to inform study of the rural nonfarm labor market in africa abstract the labor market literature in developing countries has seldom drawn on the studies of rural household income diversification this paper draws on such studies to inform future study of the rural nonfarm labor market in africa the review of evidence provides some surprising departures from traditional images of nonfarm activities of rural households among the most striking is the dominant importance in the majority of case study areas of nonfarm wage labor as compared to self employment of nonfarm sector earnings as compared to farm sector wage earnings and of local nonfarm earnings as compared to migration earnings the most worrying finding was the poor distribution of nonfarm earnings in rural areas despite the importance of these earnings to food security and farm investments this poor distribution implies significant entry barriers and market segmentation it is probable that this will lead over time to an increasingly skewed distribution of land and other assets in rural africa

investments in african agricultural research abstract over the past three decades africa s public agricultural research systems have changed in substantive ways the total number of researchers increased fourfold the dependency on expatriate researchers significantly declined while the education levels of national researchers improved initially the growth in research staff was matched by growth in expenditures but since the late 1970s real research spending has stagnated in addition loans and grants from donor agencies now account for a sizeable share of total funding for many african agricultural research systems many of the developments of the past decade in personnel expenditures and sources of support for public sector research and development r d in africa are not sustainable spending per scientist has declined continuously during the past 30 years most dramatically during the 1980s resources are spread increasingly thin over a growing group of researchers which has negative effects on the efficiency and effectiveness of agricultural research in africa

unequal societies income distribution and the social contract this paper develops a theory of inequality and the social contract aiming to explain how countries with similar economic and political fundamentals can sustain such different systems of social insurance fiscal redistribution and education finance as those of the united states and western europe with imperfect credit and insurance markets some redistributive policies can improve ex ante welfare and this implies that their political support tends to decrease with inequality conversely with credit constraints lower redistribution translates into more persistent inequality hence the potential for multiple steady states with mutually reinforcing high inequality and low redistribution or vice versa

on the optimal order of natural resource use when the capacity of the inexhaustible substitute is limited consider a general equilibrium framework where the marginal cost of extraction from several deposits of an exhaustible resource is constant in terms of an inexhaustible perfect substitute and differs between deposits the instantaneous rate of production form the inexhaustible resource is subject to a capacity constraint

encouraging private sector research for tropical agriculture summary agricultural needs in poor tropical countries differ significantly from those in temperate rich countries yet little agricultural research is performed on products for the tropics private research is particularly concentrated in rich countries this is a result of significant failures in the market for research and development r d in particular the difficulty of preventing the resale of seed in developing countries to encourage private r d in tropical agriculture traditional funding of research may be usefully supplemented by a commitment to reward developers of specific new agricultural technologies rewards tied to adoption may be especially useful in increasing up take an illustration of how a commitment to reward developers of new agricultural technologies might work is provided

measuring the impacts of agricultural research on poverty reduction policymakers are increasingly calling upon agricultural research managers to consider poverty reduction objectives when making resource allocations the authors present a simple method to measure the impact of agricultural research on the poor this method has the advantage that it presents the results in a manner consistent with commonly used measures of poverty this consistency and focus should facilitate and enhance dialogue between policymakers and research managers when deciding on resource allocations and assessing impacts on poverty reduction an illustrative application is presented using data from malawi

income distribution and macroeconomics this paper analyzes the role of wealth distribution in macroeconomics through investment in human capital it is shown that in the presence of credit markets imperfections and indivisibilities in investment in human capital the initial distribution of wealth affects aggregate output and investment both in the short and in the long run as there are multiple steady states this paper therefore provides an additional explanation for the persistent differences in per capita output across countries furthermore the paper shows that cross country differences in macroeconomic adjustment to aggregate shocks can be attributed among other factors to differences in wealth and income distribution across countries

from bond yield to macroeconomic instability a parsimonious affine model abstract we present a hybrid heston model with a common stochastic volatility to describe government bond yield dynamics the model is analytically tractable and therefore can be efficiently estimated using the maximum likelihood approach and a specific expansion in order to cope with the curse of dimensionality twofold is the model contribution first it captures changes in the yield volatility and predict future yield values of germany french italy and spain the result is an early warning indicator which anticipates phases of instability characterizing the time series investigated then the model describes convergence divergence phenomena among european government bond yields and explores the countries reactions to a common monetary policy described through the eonia interbank rate we also investigate the potential of this indicator on u s data treasury bills

price expectations ore quality selection and the supply of a nonrenewable resource abstract economic models of depletion imply that the present value price of a resource and the quality of extracted ore should be directly related the empirical evidence is that in the short run the average quality of extracted ore and in some cases metal output decline in response to a price increase this paper examines a model of extraction with heterogeneous ore quality within a deposit and revised price expectations in which this seemingly paradoxical supply response is rationalized as the outcome of ore quality selection which maximizes the present value of the mine

income inequality in the united states 1913 1998 this paper presents new homogeneous series on top shares of income and wages from 1913 to 1998 in the united states using individual tax returns data top income and wages shares display a u shaped pattern over the century our series suggest that the large shocks that capital owners experienced during the great depression and world war ii have had a permanent effect on top capital incomes we argue that steep progressive income and estate taxation may have prevented large fortunes from fully recovering from these shocks top wage shares were flat before world war ii dropped precipitously during the war and did not start to recover before the late 1960s but are now higher than before world war ii as a result the working rich have replaced the rentiers at the top of the income distribution

the rural non farm economy prospects for growth and poverty reduction summary policy makers have high expectations for the rural non farm economy rnfe given high income shares growing employment and frequently low capital requirements they see the rnfe as a potential pathway out of poverty for their rural poor yet available evidence suggests that pro poor rural non farm growth does not occur automatically for the poor to benefit from rural non farm growth policy makers must stimulate buoyant rural economies with robust non farm income growth not simply low productivity employment moreover the poor must gain access to growing market niches fluid labor markets provide one important bridge linking the rural poor to growing non farm opportunities

did higher inequality impede growth in rural china this paper estimates the relationship between initial village inequality and subsequent household income growth for a large sample of households in rural china using a rich longitudinal survey spanning the years 1987 2002 and controlling for an array of household and village characteristics the paper finds that households located in higher inequality villages experienced significantly lower income growth through the 1990s however local inequality s predictive power and effects are significantly diminished by the end of the sample the paper exploits several advantages of the household level data to explore hypotheses that shed light on the channels by which inequality affects growth biases due to aggregation and heterogeneity of returns to own resources previously suggested as candidate explanations for the relationship are both ruled out instead the evidence points to unobserved village institutions at the time of economic reforms that were associated with household access to higher income activities as the source of the link between inequality and growth the empirical analysis addresses a number of pertinent econometric issues including measurement error and attrition but underscores others that are likely to be intractable for all investigations of the inequality growth relationship

exploration and scarcity noting that a suggested measure of natural resource scarcity resource rent is unobservable we show that rent is linked to observable marginal exploration cost a two period model of extraction and exploration reveals that rent is equal to this cost when discovery is certain under risky exploration cost data can be used to bound rent the model also indicates how exploration uncertainty affects the competitive firm s extraction and exploration decisions finally the behavior of u s oil and gas exploration costs suggests that these costs were rising in the postwar era which has different implications for scarcity than indicated by other measures of scarcity

implications of implicit credit spread volatilities on interest rate modelling abstract we test seven term structure models in the heath jarrow and morton 1992 class in order to find the best representation of the libor rate in interest rate markets after the credit crunch of 2007 the libor rate is considered as a risky rate subject to the credit risk of a generic counterparty whose credit quality is refreshed at each fixing date we study the volatilities of the credit spreads implicitly obtained from libor time series in order to understand how assumed volatility functions affect interest rate curve modelling and asset pricing we develop a model to estimate basis swap prices through the monte carlo simulations we compare obtained results and individuate systematic relations existing between the basis spread forecast error and both the accuracy in volatility modelling and the accuracy of the monte carlo estimates we analyse and document these relations by defining appropriate pricing error measures

explaining international and intertemporal variations in income inequality this paper explores the propositions that income inequality is relatively stable within countries and that it varies significantly among countries a new and expanded data set provides broad support for both propositions drawing on a political economy and capital market imperfection arguments to explain the intertemporal and international variation in inequality the empirical analysis shows that the predicted variables associated with the first argument a measure of civil liberties and the initial level of secondary schooling and the second argument a measure of financial depth and the initial distribution of land are indeed important determinants of inequality this paper explores two propositions regarding income inequality they are first income inequality is relatively stable within countries and second it varies significantly across countries to illustrate note that the gini coefficient in india remained almost constant for forty years 1951 92 with mean 32 6 and standard deviation 2 0 2 in contrast the variation in gini coefficients across countries is large 61 9 in honduras in 1968 compared with 17 8 in bulgaria in 1976 if substantiated these propositions have potentially significant implications for poverty the significance of the first is obvious barring any fundamental socio political change poverty reduction will depend crucially on the rate of economic growth given this the significance of the second is that in inegalitarian economies the poor will enjoy a smaller share of any national increment in income than in more egalitarian ones drawing on a new and expanded data set on inequality deininger and squire 1996a the first of the paper s three sections conducts standard statistical tests of the two propositions the sample comprises 573 observations on the most common measure of inequality the gini coefficient for 49 developed and developing countries covering the period 1947 94 the results broadly confirm our two propositions specifically analysis of variance anova shows that about 90 of the total variance in the gini coefficients

local inequality and project choice theory and evidence from ecuador this paper provides evidence consistent with elite capture of social fund investment projects in ecuador exploiting a unique combination of data sets on village level income distributions social fund project administration and province level electoral results we test a simple model of project choice when local political power is unequally distributed in accordance with the predictions of the model poorer villages are more likely to receive projects that provide excludable private goods to the poor such as latrines controlling for poverty more unequal communities are less likely to receive such projects consistent with the hypothesis of elite capture these results are sensitive to the specific measures of inequality and elite power used in the empirical analysis and are strongest for expenditure shares at the top of the distribution

the economic and poverty impacts of maize research in west and central africa this article assembles the results of three multicountry surveys on variety performance and adoption patterns to measure the impacts of maize research in west and central africa from 1981 to 2005 and uses cost data since 1971 to compute social rates of return on public investments in maize research in the region adoption of modern varieties increased from less than 5 of the maize area in the 1970s to about 60 in 2005 yielding an aggregate rate of return on research and development r d investment of 43 the estimated number of people moved out of poverty through adoption of new maize varieties rose gradually in the 1980s to more than one million people per year since the mid 1990s over half of these impacts can be attributed to international maize research at iita and cimmyt the article concludes with a discussion of strategic options to enhance the impacts of maize research in the region

economic returns to cowpea research extension and input distribution in senegal abstract this paper calculates the rate of return to a set of cowpea research extension and distribution projects in senegal to be between 31 and 92 the results show that a modestly funded program on a secondary crop can be successful they also indicate that programs may increase their effectiveness by addressing specific household needs in this case by focusing on short cycle varieties that provide food during the hunger season prior to the traditional harvest

on the nonexistence of market equilibria in exhaustible resource markets with decreasing costs this paper examines the existence of competitive equilibria in markets for exhaustible resources where there are initial economies of scale in either the extraction of the resource or the utilization of the resource as an input in production in such instances which are fairly common we find that the classic hotelling rule for competitive extraction does not apply since competitive price equilibria generally do not exist this is in marked contrast to static markets where the usual textbook example of firms with u shaped average cost curves is not inconsistent with the existence of competitive equilibria furthermore oligopolistic market equilibria in which resource firms act as nash producers may also fail to exist when there are returns to scale in production

a new data set measuring income inequality this article presents a new data set on inequality in the distribution of income the authors explain the criteria they applied in selecting data on gini coefficients and on individual quintile groups income shares comparison of the new data set with existing compilations reveals that the data assembled here represent an improvement in quality and a significant expansion in coverage although differences in the definition of the underlying data might still affect inter temporal and international comparability based on this new data set the authors do not find a systematic link between growth and changes in aggregate inequality they do find a strong positive relationship between growth and reduction of poverty

the top 1 percent in international and historical perspective world top incomes database at http topincomes parisschoolofeconomics eu and has represented a challenge to the economics profession stories based on the and has represented a challenge to the economics profession stories based on the supply and demand for skills are not enough to explain the extreme top tail of supply and demand for skills are not enough to explain the extreme top tail of the earnings distribution nor is it enough to look only at earned incomes different the earnings distribution nor is it enough to look only at earned incomes different approaches are necessary to explain what has happened in the united states over approaches are necessary to explain what has happened in the united states over the past century and also to explain the differing experience in other high income the past century and also to explain the differing experience in other high income countries over recent decades we begin with the international comparison in the countries over recent decades we begin with the international comparison in the fi rst section and then turn to the causes and implications of the evolution of top fi rst section and then turn to the causes and implications of the evolution of top income shares income shares

reserve characteristics and mining costs an empirical study of the phosphate industry this paper deals with an estimation of phosphate mining cost function here it is argued that other characteristics of reserves besides their size could be quite important in the cost function the result of a cross sectional analysis of phosphate mining in the world shows that reserve size and average total cost have a positive and modest statistically significant relationship in one of the two models among many qualitative characteristics and location factors tested in this paper overburden grade ore product ratio water availability and the price of capital are significant with expected signs finally the results confirm the existence of economies of scale in phosphate mining which seem to be more related to mining technology than to reserve size

returns to food and agricultural r d investments in sub saharan africa 1975 2014 research enabled growth in agricultural productivity is pivotal to sub saharan africa s overall economic growth prospects yet investments in research and development rd median 38 0 py around 78 5 of the evaluations relate to the commodity specific consequences of agricultural research while 5 5 report on the returns to an all agriculture aggregate the weight of commodity specific evaluation evidence is not especially congruent with the composition of agricultural production throughout africa nor to the best that can be determined the commodity orientation of public african agricultural r d

resource characteristics extraction costs and optimal exploitation of mineral resources this paper modifies the traditional theories ofnon renewable resource exploitation where reserve sizeis assumed to be the major determinant of extractioncosts in a competitive model of resourceexploitation characteristics of aggregate reservesare considered as a determinant of extraction cost then dynamic solutions for the price and exploratoryefforts are developed various price paths arefeasible under different assumptions with regard tothe changes in the reserve characteristics over time past empirical research shows that there is noconsistent price path for all materials in fact itis the quality of newly discovered reserves as well astheir size that has affected material prices todemonstrate the complexity of a firm s decision torecover mineral from new deposits potentials forsubstantial high quality marine mineral resources areevaluated as a substitute for land based resources however several factors including the decreasingtrend in marine mining r d expenditures and thepotential impact of large scale marine mining on priceof minerals indicate that mining of mostnon hydrocarbon marine minerals will not take place inthe near future

grade selection under uncertainty least cost last and other anomalies abstract grade selection rules for heterogeneous resource deposits with increasing marginal extraction costs are derived it is shown that contrary to the conventional wisdom it can be optimal to extract the least cost deposits last there are a number of rules that are compatible with dynamic profit maximization under certainty nevertheless none explains empirical regularities in actual extraction patterns when uncertainty about future price is introduced however the theoretical model conforms closely not only to observed grade selection patterns but also to observed mineral industry price paths

principal challenges confronting smallholder agriculture in sub saharan africa summary this paper uses small scale farm survey data from five countries of eastern and southern africa to highlight four under appreciated issues i how land distribution patterns constrain the potential of crop technology and input intensification to enable many small farms to escape from poverty ii why most smallholders are unable to produce more than a marginal surplus or participate meaningfully in commodity markets iii why most farmers are directly hurt by higher grain prices and iv why the marketed agricultural surplus is exceedingly concentrated among a small group of relatively large smallholders policy and public investment options are reviewed in the light of these findings there is no one future for small farms in africa much depends on government policy and investment decisions

the rural non farm sector issues and evidence from developing countries abstract the rural non farm sector has traditionally been viewed as a low productivity sector which produces low quality goods it is often expected to wither away as a country develops recent years have seen a shift away from this position towards recognition that the rural non farm sector can and often does contribute to economic growth rural employment poverty reduction and a more spatially balanced population distribution this paper reviews the literature on the conceptual and empirical underpinnings of this more recent perspective focussing on the experience in developing countries the paper documents the size and heterogeneity of the sector pointing to evidence that in many countries the sector is expanding rather than declining the issues associated with measuring the sector s economic contribution are discussed followed by empirical assessments for several countries and regions the distributional impact of non farm earnings is examined and it is found that a pro poor impact while by no means inevitable can be considerable the sector s trajectory over time in different settings is reviewed and the scope for and experience of various policy interventions is discussed

promise and pitfalls in the use of secondary data sets income inequality in oecd countries as a case study this paper examines the role of secondary data sets in empirical economic research taking the field of income distribution as a case study we illustrate problems faced by users of secondary statistics showing how both cross country comparisons and time series analysis can depend sensitively on the choice of data after describing the genealogy of secondary data sets on income inequality we consider the main methodological issues and discuss their implications for comparisons of income inequality across oecd countries and over time the lessons to be drawn for the construction and use of secondary data sets are summarized at the end of the paper

exploration and exhaustible resources the microfoundations of aggregate models the appropriate specifications for aggregate extraction and exploration cost functions are derived from a disaggregate model of the search for low cost deposits of an exhaustible resource the common practice of combining the no discovery extraction cost function with exploration is shown to result in a misspecified model for which the total cost of extracting the resource is not well defined the widely accepted prediction that the anticipated discovery of low cost deposits results in a u shaped price path appears to be an artifact of this misspecification for the authors properly specified cost functions the predicted resource price always rises copyright 1989 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

the effects of exposure to better neighborhoods on children new evidence from the moving to opportunity experiment the moving to opportunity mto experiment offered randomly selected families housing vouchers to move from high poverty housing projects to lower poverty neighborhoods we analyze mto s impacts on children s long term outcomes using tax data we find that moving to a lower poverty neighborhood when young before age 13 increases college attendance and earnings and reduces single parenthood rates moving as an adolescent has slightly negative impacts perhaps because of disruption effects the decline in the gains from moving with the age when children move suggests that the duration of exposure to better environments during childhood is an important determinant of children s long term outcomes jel i31 i38 j13 r23 r38

sectoral supply of minerals of varying quality in this sectoral model of mineral production investment in capacity and variation in orebody grade and volume help explain some stylized facts more than one grade of ore may be exploited simultaneously mine exhaustion but not necessarily entry occurs in declining order of grade the price may rise or fall but is likely to fall initially young industry and must eventually rise at less than the interest rate unless demand expands rapidly these trends exhibit fluctuations due to entry and exhaustion of deposits resource price cyclicality is reinforced because mines keep producing at capacity when the price is falling

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

inequality does cause underdevelopment insights from a new instrument consistent with the provocative hypothesis of engerman and sokoloff 1997 2000 this paper confirms with cross country data that agricultural endowments predict inequality and inequality predicts development the use of agricultural endowments specifically the abundance of land suitable for growing wheat relative to that suitable for growing sugarcane as an instrument for inequality is this paper s approach to problems of measurement and endogeneity of inequality the paper finds inequality also affects other development outcomes institutions and schooling which the literature has emphasized as mechanisms by which higher inequality lowers per capita income it tests the inequality hypothesis for development institutional quality and schooling against other recent hypotheses in the literature while finding some evidence consistent with other development fundamentals the paper finds high inequality to independently be a large and statistically significant barrier to prosperity good quality institutions and high schooling

how progressive is the u s federal tax system a historical and international perspective this paper provides estimates of federal tax rates by income groups in the united states since 1960 with special emphasis on very top income groups we include individual and corporate income taxes payroll taxes and estate and gift taxes the progressivity of the u s federal tax system at the top of the income distribution has declined dramatically since the 1960s this dramatic drop in progressivity is due primarily to a drop in corporate taxes and in estate and gift taxes combined with a sharp change in the composition of top incomes away from capital income and toward labor income the sharp drop in statutory top marginal individual income tax rates has contributed only moderately to the decline in tax progressivity international comparisons confirm that is it critical to take into account other taxes than the individual income tax to properly assess the extent of overall tax progressivity both for time trends and for cross country comparisons the pattern for the united kingdom is similar to the u s pattern france had less progressive taxes than the united states or the united kingdom in 1970 but has experienced an increase in tax progressivity and has now a more progressive tax system than the united states or the united kingdom

technological change and risk management an application to the economics of corn production the paper investigates the linkages between technological change and production risk with an application to corn the effects of technology on risk exposure are analyzed we define technological progress to be risk increasing risk decreasing if it increases decreases the relative risk premium the analysis is applied to panel data from wisconsin research stations conditional moments including mean variance and skewness of corn yield grain moisture and corn profit are estimated for different sites we investigate how the trade off between expected return and the risk premium varies over time and over space the empirical results indicate that technological progress contributes to reducing the exposure to risk as well as downside risk in corn production although this effect varies across sites they also stress the role of the relative maturity of corn hybrids as a means of managing risk

extraction costs and the economics of nonrenewable resources the study questions the fundamental assumption of the standard aggregate exploration extraction model of nonrenewable resources that extraction costs and the level of reserves are inversely related it also raises questions about the model s conclusions regarding exploration incentives and the valuation of reserves an empirically tested disaggregate model is presented that suggests that exploration activity occurs from firms attempting to balance marginal extraction plus user costs at the intensive and extensive margins exploration is carried out until the marginal discovery cost of a deposit equals its present asset value and a u shaped price path is indicated

inequality and economic growth the empirical relationship reconsidered in the light of comparable data all of the recent empirical work on the relationship between income inequality and economic growth has used inequality data that are not consistently measured this paper argues that this is inappropriate and shows that the significant negative correlation often found between income inequality and growth across countries is not robust when income inequality is measured in a consistent manner using data from the world income inequality database however evidence is found of a significant negative correlation between consistently measured inequality of expenditure data and economic growth for a sample of developing countries

contagion in latin america definitions measurement and policy implications this paper analyzes bond and stock markets in latin america and uses these patterns to investigate whether contagion occurred in the 1990 s it defines shift contagion as a significant increase in cross market linkages after a shock to one country or region several coin toss examples and a simple model show that the standard tests for contagion are biased due to the presence of heteroscedasticity endogeneity and omitted variable bias recent empirical work which addresses these problems finds little evidence of shift contagion during a range of crisis periods instead this work argues that many countries are highly interdependent in all states of the world and the strong cross country linkages which exist after a crisis are not significantly different than those during more stable periods these findings have a number of implications for latin america

poverty reduction during the rural urban transformation the role of the missing middle as countries develop they restructure away from agriculture and urbanize but structural transformation and urbanization patterns differ substantially with some countries fostering migration out of agriculture into rural off farm activities and secondary towns and others undergoing rapid agglomeration in mega cities using cross country panel data for developing countries spanning 1980 2004 the analysis in this paper finds that migration out of agriculture into the missing middle the rural nonfarm economy and secondary towns yields more inclusive growth patterns and faster poverty reduction than agglomeration in mega cities this suggests that patterns of urbanization deserve much more attention when striving for faster poverty reduction

the impact of agricultural research on productivity and poverty in sub saharan africa while it is widely recognized that agricultural research is a key driver of broad based technological change in agriculture that benefits the poor in many different ways little is known about its aggregate impacts on productivity growth and poverty reduction in sub saharan africa ssa using a polynomial distributed lag structure for agricultural research within a simultaneous system of equations framework this paper first demonstrates that agricultural research contributes significantly to productivity growth in ssa productivity growth is again shown to raise per capita incomes with income increases finally having significant poverty reducing effects with an aggregate rate of return of 55 the payoffs to agricultural research are also impressive agricultural research currently reduces the number of poor by 2 3 million or 0 8 annually while the actual impacts are not large enough to more than offset the poverty increasing effects of population growth and environmental degradation the potential impacts of agricultural research are far greater apart from low research investments ssa faces several constraints outside the research system that hinder realization of potential research benefits the results show that doubling research investments in ssa would reduce poverty by 9 annually however this would not be realized without more efficient extension credit and input supply systems

credit spread variability in the u s business cycle the great moderation versus the great recession this paper establishes the prevailing flnancial factors that in uence credit spread variability and its impact on the u s business cycle over the great moderation and great recession periods to do so we develop a dynamic general equilibrium framework with a central role of flnancial intermediation and equity assets over the great moderation and great recession periods we flnd an important role for bank market power sticky rate adjustments and loan rate markups on credit spread variability in the u s business cycle equity prices exacerbate movements in credit spreads through the flnancial accelerator channel but cannot be regarded as a main driving force of credit spread variability both the flnancial accelerator and bank capital channels play a signiflcant role in propagating the movements of credit spreads we observe a remarkable decline in the in uence of technology and monetary policy shocks over three recession periods from the demand side of the credit market the in uence of ltv shocks has declined since the 1990i91 recession while the bank capital requirement shock exacerbates and prolongs credit spread variability over the 2007i09 recession period across the three recession periods there is an increasing trend in the contribution of loan markup shocks to the variability of retail credit spreads

trends in natural resource commodity prices an analysis of the time domain abstract this paper attempts to reconcile the theoretical predictions of increasing real prices for nonrenewable natural resource commodities obtained from hotelling style models with the empirical findings of falling prices for these commodities a theoretical model for relative price movements is derived for the case of exogenous technical change and endogenous change in the grade of ores mined the model suggests a u shaped time path for relative prices the implied price movements are tested for all the major metals and fuels and the model parameters are found to be statistically significant for 11 out of the 12 commodities tested

an economic evaluation of spread on rwanda s rural population abstractsustainable partnerships to enhance rural enterprises and agricultural development spread was a programme to enhance the value chain for commodities in rwanda including coffee the implicit concept was that improving the value chain would increase the incomes for smallholders and hence reduce the poverty rate the results indicate that rwanda coffee prices increased relative to an index price for traded coffee with the implementation of spread in addition the results indicate that participation in the coffee market at this time was associated with higher household income and lower rates of poverty

agrifood industry transformation and small farmers in developing countries summary this article introduces this special issue on the rapid transformation of the agrifood industry in developing countries and its effects on small farmers we review the literature from the late 1980s to the present and find evidence first of food processing then retail transformation and mixed evidence of impacts on small farmers both inclusion particularly with resource providing contracts and exclusion sometimes from scale constraint sometimes from inadequate non land assets the special issue papers contribute to the debate by confirming the mix of cases of inclusion and exclusion the cases are main in horticulture and dairy key hopes for smallholder development

the evolving role of agriculture in poverty reduction an empirical perspective abstract the role of agriculture in development remains much debated this paper takes an empirical perspective and focuses on poverty as opposed to growth alone the contribution of a sector to poverty reduction is shown to depend on its own growth performance its indirect impact on growth in other sectors the extent to which poor people participate in the sector and the size of the sector in the overall economy bringing together these different effects using cross country econometric evidence indicates that agriculture is significantly more effective in reducing poverty among the poorest of the poor as reflected in the 1 day squared poverty gap it is also up to 3 2 times better at reducing 1 day headcount poverty in low income and resource rich countries including those in sub saharan africa at least when societies are not fundamentally unequal however when it comes to the better off poor reflected in the 2 day measure non agriculture has the edge these results are driven by the much larger participation of poorer households in growth from agriculture and the lower poverty reducing effect of non agriculture in the presence of extractive industries

distributive politics and economic growth a crude distinction between economics and politics would be that economics is concerned with expanding the pie while politics is about distributing it in this paper we analyze the relationship between the two we focus on how an economy s initial configuration of resources shapes the political struggle for income and wealth distribution and how that in turn affects long run growth our main conclusion is that inequality is conducive to the adoption of growth retarding policies we derive this result from a simple political economy model of growth and present cross country evidence consistent with it the key feature of our model is that individuals differ in their relative factor endowments we distinguish between two types of factors an accumulated factor called capital and a nonaccumulated factor called labor growth is driven by the expansion of the capital stock which is in turn determined by individual saving decisions long run growth is endogenous as the aggregate production function is taken to be linearly homogeneous in capital and productive government services taken together the provision of government services is financed by a tax on capital because government services are productive a small tax on

market response to policy initiatives during the global financial crisis abstract this paper examines the impact of macroeconomic and financial sector policy announcements in the united states the united kingdom the euro area and japan on interbank credit and liquidity risk premia during the recent crisis overall policy interventions were associated with a reduction in interbank risk premia most significantly for recapitalization programs by contrast decisions to bail out individual banks in an ad hoc manner or let them fail were accompanied by a significant rise in interbank risk premia most policy announcements had international spillovers these results are broadly robust to using alternative measures of financial distress and varying the size of the event window

nonlinear manifold learning for early warnings in financial markets abstract a financial market is a complex dynamic system with an underlying governing manifold this study introduces an early warning method for financial markets based on manifold learning first we restructure the phase space of a financial system using financial time series data then we propose an information metric based manifold learning imml algorithm to extract the intrinsic manifold of a dynamic financial system early warning ranges for critical transitions of financial markets can be detected from the underlying manifold we deduce the intrinsic geometric properties of the manifold to detect impending crises experimental results show that our imml algorithm accurately describes the attractor manifold of the financial dynamic system and contributes to inform investors about the state of financial markets

inequality is bad for growth of the poor but not for that of the rich the paper assesses the impact of overall inequality as well as inequality among the poor and among the rich on the growth rates along various percentiles of the income distribution the analysis uses micro census data from u s states covering the period from 1960 to 2010 the paper finds evidence that high levels of inequality reduce the income growth of the poor and if anything help the growth of the rich when inequality is deconstructed into bottom and top inequality the analysis finds that it is mostly top inequality that is holding back growth at the bottom

resource taxation with heterogeneous quality and endogenous reserves abstract this paper analyzes the impact of mining taxation on the intertemporal extraction profile for a heterogeneous ore body the extraction profile specifies both quantities and qualities extracted in each period total extraction is thus endogenously determined the taxes explicitly considered are severance taxes ad valorem or per unit on metal or on ore property taxes and profits taxes with depletion allowance the intertemporal framework integrates economic and geological factors generating new results on extraction distortions and providing qualification or reconciliation of previous diverse results in this area

why don t we see poverty convergence average living standards are converging among developing countries and faster growing economies see more progress against poverty yet we do not find poverty convergence countries starting with higher poverty rates do not see higher proportionate rates of poverty reduction the paper tries to explain why analysis of a new dataset suggests that at given mean consumption high initial poverty has an adverse effect on consumption growth and also makes growth less poverty reducing thus for many poor countries the growth advantage of starting out with a low mean is lost due to a high incidence of poverty jel d63 i31 i32 o15

heterogeneity stratification and growth macroeconomic implications of community structure and school finance this paper examines how socioeconomic stratification and alternative systems of education finance affect inequality and growth agents interact through local public goods or externalities school funding neighborhood effects and economywide linkages complementary skills knowledge spillovers sorting families into homogeneous communities often minimizes the costs of existing heterogeneity but mixing reduces heterogeneity faster integration therefore tends to slow down growth in the short run yet raise it in the long run a move to state funding of education presents society with a similar intertemporal trade off local and global complementarities play major roles in determining the efficient social and educational structures copyright 1996 by american economic association

how did the fed react to the 1990s stock market bubble evidence from an extended taylor rule how did the federal reserve bank react to the stock market bubble of the late 1990s at a symposium sponsored by the federal reserve bank of kansas city in jackson hole wyoming on august 30 2002 chairman alan greenspan remarked that economists do not currently have a way to measure a stock market bubble convincingly he also argued that in the absence of such a measure it was difficult for the fed to justify with some degree of certainty a preemptive tightening that would likely be necessary to neutralize such a bubble this paper extends the taylor rule methodology to include three measures of stock market overvaluation and confirms greenspan s statement that the fed did not neutralize the bubble however the extended taylor rule methodology also shows that the fed perhaps unintentionally by keeping the fed funds rate below those suggested by the taylor rule may have actually contributed to the growth of the bubble

pitfalls im a received idea ricardian decreasing returns at the extensive margin of a natural resource the ricardi theo of constantly decreasing returs on addition units of a self renewable resource states that best resources are used firs except for location and technical change using modem economic theory we show this result to be an unfounded prejudice our moel of the origin ricardian ild problem easily splays initial increasing retumsr thus soling a 150 year old empirical puzzle carey s paradox of switches in hstorical land use pattems the ricadi result may be empirically correct in specific cases but cannot claim general theoretica validity le embuches dune ide re ue le rendements d raissants icardens a ia marge extensive duine ressource naturelle la theonre ncardienne des rendements constamment

mildly explosive dynamics in u s fixed income markets abstract we use a recently developed right tail variation of the augmented dickey fuller unit root test to identify and date stamp periods of mildly explosive behavior in the weekly time series of eight u s fixed income yield spreads between september 2002 and april 2018 we find statistically significant evidence of mildly explosive dynamics in six of these spreads two of which are short medium term mortgage related spreads we show that the time intervals characterized by instability that we estimate from these yield spreads capture known episodes of financial and economic distress in the u s economy mild explosiveness migrates from short term funding markets to medium and long term markets during the great financial crisis of 2007 09 furthermore we statistically validate the conjecture that the initial panic of 2007 migrated from segments of the abx market to other u s fixed income markets in the early phases of the financial crisis