factors determining intercropping by rubber smallholders in sri lanka a logit analysis abstract variables related to farmers awareness and attitudes towards intercropping of immature rubber hevea brasiliensis stands extension contacts education level and experience with farming other crops are positively associated with the probability of adoption higher levels of off farm income are associated with reduced intercropping in immature rubber stands farmers who are sole owners of the land and engaged in full or part time rubber farming show lower adoption rates than other land ownership groups social participation family size experience with farming rubber immature and mature rubber stands size and the nature of the land flat sloped do not significantly influence adoption these conclusions were obtained from a logit model estimated by employing the results of a survey of 588 smallholder rubber farmers from five major rubber growing regions in sri lanka

learning about a new technology pineapple in ghana this paper investigates the role of social learning in the diffusion of a new agri cultural technology in ghana we use unique data on farmers communication patterns to define each individual s information neighborhood conditional on many potentially confounding variables we find evidence that farmers adjust their inputs to align with those of their information neighbors who were surpris ingly successful in previous periods the relationship of these input adjustments to experience further indicates the presence of social learning in addition applying the same method to input choices for another crop of known technol ogy correctly indicates an absence of social learning effects jel d83 013 033 q16

impact of farmer field schools on agricultural productivity and poverty in east africa summary the authors used a longitudinal impact evaluation with quasi experimental methods to provide evidence on economic and production impact of a farmer field school ffs project in east africa ffss were shown to have positive impact on production and income among women low literacy and medium land size farmers participation in ffs increased income by 61 participation in ffs improved agricultural income and crop productivity overall this implies that farmer field schools are a useful approach to increase production and income of small scale farmers in east africa and that the approach can be used to target women and producers with limited literacy

investing in farmers the impacts of farmer field schools in relation to integrated pest management public policy in developing countries has failed to invest in educating farmers on how to deal with variable agro ecosystems and a changing world here we present an assessment of a participatory training approach in changing crop protection by farmers from chemically dependent to more sustainable practices in line with the tenets of integrated pest management ipm we review the evidence from the studies on an educational investment designed to capacitate farmers to apply ipm and discuss these data in the light of an on going policy debate concerning cost effectiveness the results indicate substantial immediate and developmental benefits of participation in farmer field schools

social networks and technology adoption in northern mozambique despite their potentially strong impact on poverty agricultural innovations are often adopted slowly using a unique household dataset on sunflower adoption in mozambique we analyse whether and how individual adoption decisions depend upon the choices of others in the same social networks since farmers anticipate that they will share information with others we expect farmers to be more likely to adopt when they know many other adopters dynamic considerations however suggest that farmers who know many adopters might strategically delay adoption to free ride on the information gathered by others we present empirical evidence that shows that the relationship between the probability of adoption and the number of known adopters is shaped as an inverse u in line with information sharing the network effect is stronger for farmers who report discussing agriculture with others the data contains information which is needed to ameliorate the identification issues that commonly arise in this context in particular social networks are precisely identified and in addition we can control for village heterogeneity and endogenous group formation

time series model forecasts and structural breaks evidence from spanish pre emu interest rates analysis of the future behaviour of economic variables can be biased if structural breaks are not considered when these structural breaks are present the in sample fit of a model gives us a poor guide to ex ante forecast performance this problem is true for both univariate and multivariate analysis and can be extremely important when co integration relationships are analysed the main goal of this article is to analyse the impact of structural breaks on forecast accuracy evaluation we focus on forecasting several interest rates from the spanish interbank money market in order to carry out the analysis we perform two forecasting exercises a without structural breaks and b when structural breaks are explicitly considered we use new sequential methods in order to estimate change points in an endogenous way this method allows us to detect structural breaks in all four rates in may 1993 however the effects of these breaks are not very strong since we found scarce gains in forecasting accuracy w

units of measurement and the stone index in demand system estimation the stone index typically used in estimating linear almost ideal demand systems is not invariant to changes in units of measurement which may seriously affect the approximation properties of the model a modification to the stone index or use of a regular price index instead are both desirable practices in estimating linear ai models

evaluating prior beliefs in a demand system the case of meat demand in canada an almost ideal demand system for meats is estimated using canadian data a bayesian approach is used to impose inequality restrictions on substitution elasticities via monte carlo integration and importance sampling in order to conform with prior beliefs about curvature and monotonicity restrictions and substitution relationships results are more consistent with the concavity and monotonicity restrictions from demand theory than with the added restriction that all meats are substitutes

maintaining and testing separability in demand systems we derive a general elasticity representation of the necessary and sufficient conditions for direct weak separability of the utility function parametric restrictions required to implement the separability conditions are presented for three common demand systems the almost ideal translog and rotterdam our empirical application uses the rotterdam model to test a few separable structures within a complete u s demand system emphasizing food commodities results based on size corrected likelihood ratio tests provide support for commonly used separability assumptions about food and meat demand

agricultural extension and technology adoption for food security evidence from uganda we evaluate causal impacts of a large scale agricultural extension program for smallholder women farmers on technology adoption and food security in uganda through a regression discontinuity design that exploits an arbitrary distance to branch threshold for village program eligibility we find eligible farmers used better basic cultivation methods achieved improved food security given minimal changes in adoption of relatively expensive inputs we attribute these gains to improved cultivation methods that require low upfront monetary investment farmers also modified their shock coping methods these results highlight the role of information and training in boosting agricultural productivity among poor farmers and indirectly improving food security

measuring food insecurity the frequency and severity of coping strategies abstract defining and interpreting food security and measuring it in reliable valid and cost effective ways have proven to be stubborn problems facing researchers and programs intended to monitor food security risks this paper briefly reviews the conceptual and methodological literature on food insecurity measurment describes a particular method for distinguishing and measuring short term food insecurity at the household level and discusses ways of generalizing the method the method developed enumerates the frequency and severity of strategies relied on by urban households when faced with a short term insufficiency of food this method goes beyond more commonly used measures of caloric consumption to incorporate vulnerability elements of food insecurity as well as the deliberate actions of household decision makers when faced with food insufficiency

on price indices in the almost ideal demand system a number of papers have discussed the relationship between the almost ideal demand system aids and its linear approximation la aids in this paper it is shown that if the prices in the system are normalized to one the aids and la aids representations are identical at the point of normalization also at the point of normalization the expressions for price and expenditure elasticities from both systems are identical

bias in estimating the almost ideal demand system with the stone index approximation this paper shows that the commonly used stone index approximation can bias the parameter estimates of the almost ideal demand system the bias mostly affects the price parameters and can be more serious when the budget share equations are estimated with individual household rather than aggregate data in the absence of strong substitution effects the price parameter bias can be largely corrected through simple reparameterization copyright 1993 by royal economic society

consumption versus asset smoothing testing the implications of poverty trap theory in burkina faso abstract despite solid theoretical foundations for the notion that poor borrowing constrained households will intertemporally manage assets to smooth consumption the consumption smoothing hypothesis has not always withstood empirical scrutiny this paper reassesses the intertemporal asset management problem with a poverty trap model and shows that we would expect to see asset smoothing not consumption smoothing in the neighborhood of critical asset levels at which optimal accumulation behavior bifurcates we then employ threshold estimation techniques to empirically confirm the co existence of consumption and asset smoothing regimes using a household panel data set from west africa households above the estimated threshold almost completely insulate their consumption from weather shocks whereas those below the threshold do not these results not only indirectly provide evidence of the existence of poverty traps but also speak to the level and incidence of the costs of uninsured risk

asset smoothing consumption smoothing and the reproduction of inequality under risk and subsistence constraints abstract a growing literature asks whether low wealth agents can accumulate assets over time or whether they are trapped in poverty this paper develops a stochastic dynamic programming model with endogenous asset price risk to explore savings and portfolio decisions in a resource poor environment characterized by risk and subsistence constraints optimal portfolio strategies are found to bifurcate despite divisible assets and fully rational agents wealthier agents acquire a higher yielding portfolio and pursue conventional consumption smoothing poorer agents acquire a less remunerative portfolio and pursue asset smoothing rather than consumption smoothing asset based risk coping thus results in positive correlation between initial wealth and portfolio rate of return

demand for beef and chicken products separability and structural change several studies have indicated that the recent shift from beef to poultry in consumption is not entirely caused by changes in rela tive prices or income braschler chavas dahlgran hudson and vertin moschini and meilke frank thurman most studies of structural change have focused on red meat consumption only thurman has looked closely at the poultry market and no one has considered poultry products yet the mix of chicken products marketed changed dramat ically during the last twenty years and should have influenced aggregate meat demand the share of broiler slaughter marketed as whole birds declined from 74 in 1965 to 28 in 1985 while cut up parts and processed chick en products increased from 26 to 72 whole birds are inferior goods and cut up parts and processed chicken are normal goods haidacher et al the shift in chicken prod uct mix away from whole birds should have increased the preference for total chicken in this article two related questions are ad dressed first do consumers allocate expendi tures among meats by animal origin or by product type second does disaggregation of meat into products in a meat demand model give insight into the causes of structural

applying theil s multinomial extension of the linear logit model to meat expenditure data one of the chief drawbacks of the multinomial extension of the linear logit model is that after the standard linearization the parameters which are directly estimated have no obvious economic meaning this paper presents alternative transformations which facilitate interpretation in one linearization the estimated coefficients will be elasticities at a selected data point such as the mean in another form the coefficients will be slutsky parameters the latter version is chosen for an empirical analysis of the demand for meat in great britain a number of issues concerning the model s error structure and dynamic specification are discussed

lemon technologies and adoption measurement theory and evidence from agricultural markets in uganda to reduce poverty and food insecurity in africa requires raising productivity in agriculture systematic use of fertilizer and hybrid seed is a pathway to increased productivity but adoption of these technologies remains low we investigate whether the quality of agricultural inputs can help explain low take up testing modern products purchased in local markets we find that 30 of nutrient is missing in fertilizer and hybrid maize seed is estimated to contain less than 50 authentic seeds we document that such low quality results in low average returns if authentic technologies replaced these low quality products however average returns are high to rationalize the findings we calibrate a learning model using data from our agricultural trials because agricultural yields are noisy farmers ability to learn about quality is limited and this can help explain the low quality equilibrium we observe but also why the market has not fully collapsed

an application of cointegration theory in the estimation of the almost ideal demand system for food consumption in bulgaria abstract the almost ideal demand system is applied to consumption in bulgaria it is argued that the conventional estimation of the almost ideal model should be done within the framework of contemporary time series methodology in this paper the canonical cointegrating regression procedure of park is applied it is argued that the results of the almost ideal demand system that are presented are consistent with both theory and casual observation of consumer behaviour in bulgaria

flexible specification of mixed demand systems common flexible functional forms are not very useful for modeling mixed demand systems because derivation of mixed demands requires closed forms for both direct and indirect utility functions in this paper we study the alternative of using a direct approximation to mixed demands we develop a new approach to slutsky relations for mixed demand functions allowing formulation of a rotterdam mixed demand model the resulting mixed demand system is illustrated with an application to meat demand in canada

an error correction almost ideal demand system for meat in greece this paper represents a dynamic specification of the almost ideal demand system aids based on recent developments on cointegration techniques and error correction models based on greek meat consumption data over the period 1958 1993 it was found that the proposed formulation performs well on both theoretical and statistical grounds as the theoretical properties of homogeneity and symmetry are supported by the data and the lechatelier principle holds regardless of the time horizon beef and chicken may be considered as luxuries while mutton lamb and pork as necessities in the short run beef was found to have price elastic demand pork an almost unitary elasticity whereas mutton lamb chicken and sausages had inelastic demands in the long run beef and pork were found to have a demand elasticity greater than one whereas mutton lamb chicken and sausages still had inelastic demands all meat items are found to be substitutes to each other except chicken and mutton lamb and pork and chicken

on forecasting interest rates an efficient markets perspective abstract efficient markets do not preclude economic agents from successfully forecasting movements in short term interest rates for brief forecast intervals however ex ante changes in long term rates are sufficiently close to zero that economic agents are not likely to improve upon the no change prediction of the martingale model economic agents in effect are not likely to succeed in forecasting short term movements in long term interest rates this paper illustrates the closeness of the martingale approximation for two sets of canadian interest rates data emphasizing the importance of the forecast interval the paper then examines three sets of recorded forecasts of canadian interest rates and finds results consistent with the theoretical discussion

the impact of agricultural extension and roads on poverty and consumption growth in fifteen ethiopian villages this article investigates whether public investments that led to improvements in road quality and increased access to agricultural extension services led to faster consumption growth and lower rates of poverty in rural ethiopia estimating an instrumental variables model using generalized methods of moments and controlling for household fixed effects we find evidence of positive impacts with meaningful magnitudes receiving at least one extension visit reduces headcount poverty by 9 8 percentage points and increases consumption growth by 7 1 percentage points access to all weather roads reduces poverty by 6 9 percentage points and increases consumption growth by 16 3 percentage points these results are robust to changes in model specification and estimation methods

short run and long run elasticities for canadian consumption of alcoholic beverages an error correction mechanism cointegration approach elasticities for beer wine and spirits are estimated for each of the provinces of canada over the period 1956 83 using unrestricted dynamic regressions modeled after the error correction mechanism alternative long run estimates are also obtained from cointegrating regressions estimates vary markedly across provinces and suggest that increases in price will reduce consumption of all beverages in the short run but in the long run no evidence is found that spirits use is price sensitive increases in the legal drinking age reduce consumption in the short run but there is little indication of a long run effect the estimated income elasticity of beer is small while the estimated income elasticities for spirits and wine are substantially larger especially in the long run coauthors are ernest h oksanen michael r veall and deborah fretz copyright 1992 by mit press

seeing is believing evidence from an extension network experiment extension is designed to enable lab to farm technology diffusion decentralized models assume that information flows from researchers to extension workers and from extension agents to contact farmers cfs cfs should then train other farmers in their communities such a modality may fail to address informational inefficiencies and accountability issues the authors run a field experiment to measure the impact of augmenting the cf model with a direct cf training on the diffusion of a new technology all villages have cfs and access the same extension network in treatment villages cfs additionally receive a three day central training on the new technology they track information transmission through two nodes of the extension network from extension agents to cfs and from cfs to other farmers directly training cfs leads to a large statistically significant increase in adoption among cfs however higher levels of cf adoption have limited impact on the behavior of other farmers

gender agricultural production and the theory of the household virtually all models of the household assume that the allocation of resources is pareto efficient within many african households agricultural production occurs on many plots controlled by different members of the household pareto efficiency implies that factors should be allocated efficiently across these plots i find in contrast that plots controlled by women are farmed much less intensively than similar plots within the household controlled by men the estimates imply that about 6 percent of output is lost because of inefficient factor allocation within the household the paper suggests a new approach to modeling intrahousehold allocation consistent with the empirical results

aid under fire development projects and civil conflict we estimate the causal effect of a large development program on conflict in the philippines through a regression discontinuity design that exploits an arbitrary poverty threshold used to assign eligibility for the program we find that barely eligible municipalities experienced a large increase in conflict casualties compared to barely ineligible ones this increase is mostly due to insurgent initiated incidents in the early stages of program preparation our results are consistent with the hypothesis that insurgents try to sabotage the program because its success would weaken their support in the population

the impact of agricultural extension on farm production in resettlement areas of zimbabwe in this paper we revisit the contested issue of the impact of agricultural extension on farm production we exploit two features of the data available to us its longitudinal nature and explicit measures of farmer ability we find that after controlling for innate productivity characteristics and farmer ability either using household fixed effects estimation or by including a measure of farmer ability and village fixed effects access to agricultural extension services defined as receiving one or two visits per agricultural year raises the value of crop production by about 15 per cent this parameter estimate is statistically significant however we also find variability in these parameter estimates across individual crop years with the impact being markedly different in drought and non drought years collectively these results suggest that although access to farm level extension visits does increase productivity even after controlling for innate productivity characteristics and farmer ability results from single year cross sectional studies should be treated with caution

how high are rates of return to fertilizer evidence from field experiments in kenya the idea that peasant farmers are rational profit maximizers has been a staple of development economics since theodore schultz 1964 it has also been influential in shaping policy for example agricultural experts have stressed the importance of fertilizer use in raising agricultural yields pointing to impressive results on experimental farms and to huge differences in agricultural productivity across countries with different levels of fertilizer use robert evenson and douglas gollin 2003 historically many countries subsidized fertilizer in response but economists have been skeptical of claims that farmers are leaving money on the table noting that fertilizer may not have the same returns on real world farms as on experimental farms that returns to fertilizer may be low for many farmers even if they are high on average tavneet suri 2007 that fertilizer may require complementary inputs or may be risky many countries have withdrawn or scaled back fertilizer psychology and development theory and experimental evidence

market and survey forecasts of the three month treasury bill rate in this article four readily available one quarter ahead forecasts of the three month u s treasury bill rate are compared the forecasts considered are 1 a prediction from the futures market 2 a forecast derived from an implicit forward rate calculation 3 a survey gathered forecast and 4 a no change forecast each forecast is examined for general forecast accuracy and for the extent of bias contained in each forecast over the twelve year period 1977 88 results indicate that the futures rate statistically dominates the other three forecasts while the survey and forward rate projections generally are found to be the least accurate and most biased copyright 1992 by university of chicago press

nudging farmers to use fertilizer theory and experimental evidence from kenya we model farmers as facing small fixed costs of purchasing fertil izer and assume some are stochastically present biased and not fully sophisticated about this bias such farmers may procrastinate post poning fertilizer purchases until later periods when they may be too impatient to purchase fertilizer consistent with the model many farmers in western kenya fail to take advantage of apparently profit able fertilizer investments but they do invest in response to small time limited discounts on the cost of acquiring fertilizer free deliv ery just after harvest calibration suggests that this policy can yield higher welfare than either laissez faire policies or heavy subsidies

forecasting canadian short term interest rates the author investigates the forecasting performance of a number of simple prediction techniques for short term interest rates in particular quarterly forecasts of canadian three month t bill rates from one to forty quarters in the future are generated during 1963 92 using several time series methods and market based yield curve strategies comparison is made with the martingale and for a shorter recent sample with the predictions made by several economic forecasters for the most part utilization of the yield curve proved best though it must be granted that no methodology was able to outperform the martingale for horizons up to a year

a century long perspective on agricultural development this article strategically surveys the past century s literature on agricultural development we organize the discussion around three grand themes that reveal the richness of agricultural development as an intellectual endeavor first we explore the role of agriculture in the broader development process from a macroeconomic and political economy perspective we then examine the role of technological and institutional change in successful agricultural development finally the focus turns to a microeconomic perspective on agricultural household decision making and the problems of imperfect and missing markets asymmetric information and transactions costs that lead to widespread apparent inefficiency and disequilibrium

testing restrictions on a model of japanese meat demand tests for quasi separability net substitutability and perfect substitutability are developed and implemented on an almost ideal demand system model of the japanese meat sector the data set satisfies both symmetry and homogeneity there is evidence of net complimentarity between chicken and dairy beef and chicken and pork the tests indicate that japanese wagyu beef is considered a separate commodity to both imported beef and dairy beef the results also indicate that fish can be treated as separable in the japanese meat demand system

neighbors and extension agents in ethiopia who matters more for technology adoption improving agricultural productivity is seen as vital to economic growth in poor countries particularly in sub saharan africa where productivity growth has lagged behind that of other continents the focus has therefore been on new technologies particularly the adoption and diffusion of improved seed varieties and the increased use of fertiliser supported by investments in effective extension services it is important to understand how these new technologies spread and the effectiveness of extension services in this process

beyond the field the impact of farmer field schools on food security and poverty alleviation summary we estimate the impact of a farmer field school intervention among small scale farmers in northern tanzania on two main development objectives food security and poverty we employ a series of evaluation methodologies including a quasi difference in difference setup to account for potential selection into the project despite lack of baseline data we find strong positive effects on food security but no effect on poverty investigating possible mechanisms for this result shows that reallocation of labor resources toward own agricultural production and improved production smoothing may have led to improved food security while poverty remained unaffected

gender and the dynamics of technology adoption empirical evidence from a household level panel data very few empirical studies account for the dynamic nature of the agricultural technology adoption decision and none of these explores if this dynamic nature depends on the gender of the decision maker using four waves of a household level ugandan panel data this is the first empirical analysis to account for self learning one s own adoption experience in explaining current adoption decision in a developing country context and the first to study the interaction between self learning and gender technology adoption is defined as adoption of hybrid seed inorganic fertilizer or pesticides our results indicate that the dynamic panel data probit model is superior to its static counterpart in the sense that self learning captured by lagged technology adoption indicators is by far the most important determinant of technology adoption we also find a weaker impact of self learning for female headed households than male headed households female headed households face fewer learning opportunities which produce a lower self learning impact in later periods further exacerbating the gap in technology adoption among male and female headed households

the treasury yield curve as a cointegrated system this paper examines the temporal relationship between interest rates on treasury securities ranging in maturity from three months to 30 years we find strong empirical support that the seven treasury rates selected are cointegrated a conclusion that is insensitive to the normalization chosen in particular the hypothesis of noncointegration is rejeeted decisively regardless of the rate selected as the dependent variable in the cointegrating equation to determine whether this information can be used to improve forecasts of treasury rates the seven rates are forecasted with a corresponding erroreorrection model that is shown to outperform an augmented var model that ignores the cointegration of the rates the results are consistent with the belief that arbitrage limits the extent to which rates on different maturities of a given security diverge in addition the results confirm the appropriateness of imposing a common stochastic process for interest rates in equilibrium models of the term structure

simultaneity and structural change in u s meat demand an inverse of the almost ideal demand system the iaids is developed in order to test the endogeneity of prices and quantities in the u s meat demand system the iaids has all the desirable theoretical properties of the aids except aggregation from the micro to the market level using annual data both prices and quantities appear to be endogenous within the entire meat market including livestock production costs and technical change indicators as instruments eliminates evidence of a mid 1970s demand change