grain transport and rural credit in mozambique solving the space time problem this paper shows how credit market failures can lead to large welfare losses in grain markets by inducing increased transport for seasonal storage in locations with low credit costs the burden of these welfare losses falls primarily on rural households these conclusions are obtained from a spatial temporal model solved using a mixed complementarity formulation that easily handles interest rate differentials across space efforts to address credit market failures and to improve the efficiency of rural storage should be given priority as opposed to the creation of large formal sector grain collection centers

long term growth and short term economic instability when learning by doing is at the origin of growth the long run growth rate should be negatively related to the amplitude of the business cycle if human capital accumulation is increasing and concave in the cyclical component of production empirical evidence strongly supports this nding for industrialized countries and european regions using the standard control variables we nd that countries and regions that have a higher standard deviation of growth and of unemployment have lower growth rates the result does not come from an e ect of instability on investment the negative relation however does not hold for non industrialized countries for which learning by doing may not to be the main engine of growth 2000 elsevier science b v all rights reserved jel classixcation o40 e32

the impact of transport and transaction cost reductions on food markets in developing countries evidence for tempered expectations for burkina faso reductions in transport and transaction costs are expected to have a major effect on the functioning of food markets in developing countries for burkina faso this is a relevant issue as it may have important consequences for the food markets in urban and rural deficit areas a partial equilibrium model is presented to analyze the short term effects of reduced costs on price formation inter regional cereal trade and farmers and traders storage strategies our results show that the high expectations with regard to the direct effects of cost reductions on food prices and food availability require some nuance the effects of a reduction of transport costs will be small moreover also the unintended negative consequences on the competitive position of farmers and traders in other regions that do not profit from road construction should be taken into account finally it is concluded that only if transport and transaction costs are reduced simultaneously will both the consumers and farmers benefit significantly c 2004 elsevier b v all rights reserved

a global vector autoregression model for the analysis of wheat export prices food commodity price fluctuations have an important impact on poverty and food insecurity across the world conventional models have not provided a complete picture of recent price spikes in agricultural commodity markets and there is an urgent need for appropriate policy responses perhaps new approaches are needed to better understand international spill overs the feedback between the real and the financial sectors as well as the link between food and energy prices in this article we present the results from a new worldwide dynamic model that provides the short and long run impulse responses of the international wheat price to various real and financial shocks

inventories stock outs and production smoothing if stock outs are ignored and if demand shocks are additive then optimal behaviour requires that the marginal cost of production mc be equated with the expected marginal revenue of increasing expected sales by one unit emr however with more general demand shocks and still ignoring stock outs the excess of mc over emr has the same sign as the covariance of the slope of the demand curve and the marginal valuation of inventory the equality of emr and mc is also broken by taking account of stock outs even if demand shocks are additive if there is a production lag then taking account of stock outs implies that optimal behaviour will be characterized by production smoothing even if the cost of production is linear two alternative definitions of production smoothing are presented and optimal behaviour in the presence of stock outs displays each type of smoothing it is a well known proposition that a firm producing a storable good under conditions of increasing marginal cost will tend to smooth the time profile of its production relative to the time profile of its sales the incentive to smooth production arises from the fact that the cost function is a convex function of the level of production for a given average level of production average costs can be reduced by reducing the variation in production of course if the cost function is linear in the level of production then this incentive to smooth production disappears however we will demonstrate in this paper that if the possibility of stock outs is explicitly incorporated into the firm s dynamic optimization problem i e if we impose a non negativity constraint on inventories and if there is a lag in production then optimal behaviour can be characterized by production smoothing even if the cost function is linear

how to use aggregation and combined forecasting to improve seasonal demand forecasts standard forecasting methods that are designed to cope with seasonal demand often are no longer applicable in practice due to growing assortments and shorter product life cycles demand data may show too high variation or may be insufficient to construct reliable forecast models at the individual item level in this article we present alternative forecasting methods that are based on using demand information from a higher aggregation level and on combining forecasts sales data from two prominent dutch wholesalers are used to illustrate the drawbacks of the standard seasonal forecasting methods and to demonstrate the potential of the new methods the average reduction in forecast error in terms of mse turns out to be three times as large as reported in earlier studies on common seasonal patterns

market integration and price transmission in consumer markets of developing countries abstract world prices for agricultural commodities surged in 2006 08 and then again in 2011 12 in many developing countries consumer prices for staple foods such as bread and rice mirrored these movements this paper examines whether prices in urban consumer markets within developing countries are co integrated with prices in world agricultural commodity markets using a single equation error correction model we examine the response of consumer prices for wheat rice maize and sorghum to changes in world market prices and exchange rates in urban centers of the developing world analyzing over 60 country commodity pairings we find that developing countries consumer markets are co integrated with world markets yet we also find that the transmission of changes in both world prices and real exchange rates to domestic consumer prices is not high and that the movement of domestic consumer prices to new equilibrium with world prices after a shock to the latter is relatively slow

global oil prices and local food prices evidence from east africa it is widely believed that oil prices impact food prices in developing countries yet rigorous evidence on this relationship is scarce using maize and petrol price data from east africa we show that global oil prices do affect food prices but primarily through transport costs rather than through biofuel or production cost channels we find that global oil prices transmit much more rapidly to the pump and then to local maize prices than do global maize prices suggesting that the immediate effects of correlated commodity price shocks on local food prices are driven more by transport costs than by the prices of the grains themselves furthermore we present suggestive evidence that for markets furthest inland changes in world oil prices have larger effects on local maize prices than do changes in world maize prices

testing the central market hypothesis a multivariate analysis of tanzanian sorghum markets the central market hypothesis is important in the analysis of market integration because it implies a specific market structure while avoiding a simultaneity problem however despite its importance the central market hypothesis is difficult to test and is therefore often assumed this article shows that the hypothesis can be tested in a johansen cointegration test provided that prices are nonstationary this approach is applied to reveal the existence of central markets for sorghum in tanzania the results indicate that the tanzanian sorghum market can be grouped into two market regions with prices being determined in a central market in each region

an evaluation of volatility forecasting techniques the existing literature contains conflicting evidence regarding the relative quality of stock market volatility forecasts evidence can be found supporting the superiority of relatively complex models including arch class models while there is also evidence supporting the superiority of more simple alternatives these inconsistencies are of particular concern because of the use of and reliance on volatility forecasts in key economic decision making and analysis and in asset option pricing this paper employs daily australian data to examine this issue the results suggest that the arch class of models and a simple regression model provide superior forecasts of volatility however the various model rankings are shown to be sensitive to the error statistic used to assess the accuracy of the forecasts nevertheless a clear message is that volatility forecasting is a notoriously difficult task

empirical effects of short term export bans the case of african maize abstract temporary export restrictions have been widely used in recent years in an attempt to stabilize domestic prices of staple grains i use monthly market level price data to investigate the empirical effects of 13 short term export bans on maize implemented by 5 countries in east and southern africa i find no statistically significant effect of export bans on the price gaps between pairs of affected cross border markets my results for price gaps match those from a model simulation in which export bans are not implemented however prices and price volatility in the implementing country are significantly higher during export ban periods in the data than in the model simulation with no bans export bans in the region are imperfectly enforced divert trade into the informal sector and appear to destabilize domestic markets rather than stabilizing them

spatial equilibrium and price transmission between southern african maize markets connected by informal trade policies regulating the international grain trade in southern africa sa are motivated by uncertainty regarding private sector performance and in turn private sector performance is generally constrained by the policy environment we study spatial price transmission between sa maize markets where trade is dominated by informal product flows this provides an opportunity to study private sector market performance in a largely unregulated market environment contrary to some existing evidence on the performance of sa grain markets connected by formal trade we find that informally trading markets work quite well long run price equilibrium is consistent with competitive trade price transmission is rapid and potential trade constraints have no disruptive impact on long run relationships nevertheless we do find evidence of occasionally high transfer costs that may impede informal trade flows the conclusion is that a policy focus on encouraging informal trade and lowering informal trade costs would lead to improved market performance

the fischer black hypothesis some time series evidence we estimate an arch m model to analyze the relationship between the conditional standard deviation of real gross national product gnp and its growth rate for the period 1871 1993 we find that variability significantly increases output growth rates in addition impulse response functions show that the effect of variability on growth rates is dynamic these results provide evidence in favor of black s 1987 business cycle hypothesis

the great moderation and the relationship between output growth and its volatility this study examines the effect of the great moderation on the relationship between u s output growth and its volatility over the period 1947 to 2006 first we consider the possible effects of structural change in the volatility process in so doing we employ garch m and arch m specifications of the process describing output growth rate and its volatility with and without a one time structural break in volatility second our data analyses and empirical results suggest no significant relationship between the output growth rate and its volatility favoring the traditional wisdom of dichotomy in macroeconomics moreover the evidence shows that the time varying variance falls sharply or even disappears once we incorporate a one time structural break in the unconditional variance of output starting 1982 or 1984 that is the integrated garch effect proves spurious finally a joint test of a trend change and a one time shift in the volatility process finds that the one time shift dominates

application of multi steps forecasting for restraining the bullwhip effect and improving inventory performance under autoregressive demand recent research suggests that the bullwhip effect or increasing variability of inventory replenishment orders as one moves up a supply chain illustrates inventory management inefficiencies this paper quantifies the bullwhip effect in the case of serially correlated external demand if autoregressive models are applied to obtain multiple steps demand forecasts a materials requirements planning mrp based inventory management approach is proposed to reduce the order variance simulation modeling is used to investigate the impact of the forecasting method selection on the bullwhip effect and inventory performance for the most downstream supply chain unit the mrp based approach is shown to reduce magnitude of the bullwhip effect while providing the inventory performance comparable to that of a traditional order up approach the application of autoregressive models compares favorably to other forecasting methods considered according to both the bullwhip effect and inventory performance criteria

estimating policy effects on spatial market efficiency an extension to the parity bounds model the standard parity bounds model pbm is extended to allow for dynamic shifts in regime probabilities in response to changes in marketing policy the approach allows estimation of the length of the adjustment period and a statistical test for no policy effects the extended pbm is applied to maize and wheat markets in ethiopia evidence of a dynamic adjustment path is found and grain marketing reforms are found to have improved spatial efficiency in a few markets worsened it in a few others but generally to have had little effect on the spatial efficiency of ethiopian grain markets

the transmission of world maize price to south african maize market a threshold cointegration approach this article seeks to provide an explanation for the relationship between domestic maize price in south africa and world maize prices in order to evaluate comovement and transmission of world prices to domestic prices in sub sahara african countries this is done by comparing nested and nonnested models that capture different forms of nonlinearity in the price spread adopting a bayesian approach that allows for comparison of models using bayes factor we found that the relationship between south african price and world price for maize indicates the presence of nonlinearity in price transmission with three regimes that is triggered by the price spread in previous period

the effects of ncpb marketing policies on maize market prices in kenya the government of kenya pursues maize marketing policy objectives through the national cereals and produce board ncpb which procures and sells maize at administratively determined prices and stores maize as a contingency against future shortages a private sector marketing channel competes with the ncpb this article estimates the effects of ncpb activities on the historical path of private sector prices in kenyan maize markets between 1989 and 2004 the analysis is carried out using a reduced form vector autoregression model var estimated with sparse data and imposing only minimal identification restrictions results show that ncpb activities have stabilized maize market prices in kenya reduced price levels in the early 1990s and raised average price levels by roughly 20 between 1995 and 2004 over the past decade the price raising activities of the ncpb have transferred income from urban consumers and a majority of small scale farm households that are net buyers of maize to a relatively small number of large and small scale farmers who are sellers of maize

inventory investment and output volatility abstract this paper reports the results of a detailed examination of the hypothesis that improved inventory management and production techniques are responsible for the decline in the volatility of u s gdp growth our innovations are to look at the data at a finer level of disaggregation than previous studies to exploit cross sectional heterogeneity to obtain clearer identification of this hypothesis and to provide a complete decomposition of the change in gdp volatility at the aggregate level changes in inventory behavior can account directly for almost half of the total reduction in gdp volatility however reduced volatility of sales and lower covariance among the output of major sectors in the economy each account for more than one fourth of the reduction in gdp volatility improved inventory management appears to be associated loosely with lower volatility at the industry level

structural transformation of cereal markets in ethiopia abstractwe study cereal markets in ethiopia over the last decade a period that has been characterised by important local changes including strong economic growth urbanisation improved road and communication infrastructure and higher adoption of modern inputs in agriculture these changes are associated with better spatial price integration as well as with significant declines in real price differences between supplying and receiving markets and in cereal milling and retail margins in short important improvements have occurred in ethiopia s cereal marketing system this is especially important because dysfunctional cereal markets were previously identified as an important cause of food insecurity in the country

peasant household behaviour with missing markets some paradoxes explained a model of peasant household behavior under varying degrees of household specific food and labor market failures is constructed to show that these structural features can explain several well known patterns of peasant response which have often been attributed to peculiar motives presumed specific to peasants the model explains sluggish response to cash crops prices and high instability in perceived food and labor scarcities the key role of manufactured consumer goods prices in stimulating peasants effort in cash crops production the effectiveness of taxation as opposed to incentives in stimulating cash crops production and the key role of technological change in food production to enhance cash crop production results are obtained analytically in the case of one market failure and by numerical simulation with more than one

the seasonal and spatial dimensions of sorghum market liberalization in mexico mexico s attempt to deregulate its sorghum market in 1990 was unsuccessful because policy analysts failed to consider the seasonal and spatial dimensions of trade in this paper i present a detailed seasonal and spatially dissaggregated nonlinear programming model of the mexican sorghum market calibrated with survey data of storage and transport costs in mexico and compare the results obtained with models that ignore these characteristics the comparison demonstrates that the failure to incorporate these costs in trade models may lead to misleading conclusions and inappropriate policies

determinants and effects of income diversification amongst farm households in burkina faso using four years of household data from three agroecological zones in burkina faso sahelian sudanian and guinean the article examines the determinants and effects of household income diversification harvest shortfalls and terms of trade are found to drive diversification but land constraints do not income diversification is associated with higher incomes and food consumption and more stable income and consumption over years

a spatial analysis of maize marketing policy reforms in zambia in this study we analyze recent and proposed maize marketing reforms in zambia to capture the effects of changing transport systems we use a continuous space model in place of the traditional point representation model of takayama and judge this method permits us to use prereform data on supply demand and transport costs to infer both intra and interregional effects of liberalization and shows that the welfare gains from liberalization are larger than commonly thought these results provide policy makers with estimates of the magnitude of change associated with alternative reform programs beyond what would be available from a conventional approach

inventories and sticky prices note in a recent contribution to this review alan blinder provides an interesting analysis of the relationship between optimal inventory decisions and the process of price adjustment arguing that inventory permits separation of production and sale decisions and allows the firm greater flexibility in responding to anticipated demand disturbances blinder shows that the responsiveness of relative prices depends critically upon the cost of storage and the temporal structure of the demand shocks few economists would fault the intuitive substance of blinder s basic proposition and the proposition is justified with characteristic precision the analysis however is considerably less general than blinder maintains the formal argument of his paper relies upon a simple model of a monopolist capable of backlogging orders and storing unsold goods as the model is constructed order backlogs assume a role of fundamental importance in any stationary equilibrium this feature of the model vitiates blinder s extension of his result to situations in which order backlogs are prohibited the basic monopoly model developed in sections i and ii of blinder s paper places no restriction upon the sign of inventory negative inventory is interpreted as net unfilled orders while no distinction is drawn between reductions in gross inventory and additions to the order backlog as a result the cost of holding inventory is symmetric around an arbitrary minimum point the only role of inventory is to permit the time paths of production and sales to differ gross inventory allows production to antedate sales while order backlogs generate revenue before production costs are borne under these circumstances if future costs and revenues are discounted it is natural to expect any stationary equilibrium level of net inventory to be negative this can be shown to be true of blinder s model it is useful to distinguish in general between the nonstochastic stationary level of inventory n and the stochastic stationary level n the former is realized when the current expected demand disturbance eo is zero and production equals sales the latter which differs from customary usage represents the level of inventory expected to prevail when adjustment to the current nonzero expected demand disturbance is complete if the demand disturbance is not a random walk so that p 1 in blinder s 5 the two equilibria coincide relatively little attention is devoted to either stationary solution because blinder s main interest is in the optimal current solution level n1 the stochastic stationary level is crucially important however since it represents the goal toward which the current choice must provide an optimal first step to verify that both nand n are negative whenever production is strictly positive note that blinder s necessary condition 7 with the coefficient cl set equal to zero together with the definition of xa as the deviation of the shadow value of inventory q from its nonstochastic stationary value q implies

rational expectations and the smoothing properties of inventories of finished goods abstract this paper formulates and estimates a dynamic rational expectations equilibrium model of inventories of finished goods and employment of labor the view that the primary role of inventories of finished goods is to act as a buffer stock in the face of fluctuating demand is examined both the model and estimation results indicate that this is the case because of differences in the costs involved for firms in changing their inventory stocks and labor force in addition to providing some new evidence on the behavior of inventories of finished goods and employment the paper illustrates a technology for maximum likelihood estimation of structural parameters under the hypothesis of rational expectations

inventories and the volatility of production a stylized fact associated with inventory behavior is that the variance of production exceeds the variance of sales this paper presents a model of production decisions with demand uncertainty that incorporates no nnegativity constraints on inventories even with no productivity shocks optimal behavior by the firm is consistent with this stylized fact either if demand exhibits positive serial correlation or if the firm can backlog excess demand the reason is that a demand shock affects both the actual inventory level given unchanged production and the desired level production must replenish the stock and adjust to the new desired level copyright 1987 by american economic association

inventory dynamics under transaction costs a conceptual model of storage behavior is developed optimal intertemporal pricing is derived to analyze the effects of transaction costs on storage andarbitrage pricing it is shown how transaction costs can rationalize the existence of an inverse carrying charge for inventory the model is applied to u s soybeans stocks for the period 1960 95 the empirical results suggest that transaction costs have a significant influence on storage behavior andintertemporal arbitrage pricing copyright 2000 oxford university press

government spending growth and poverty in rural india using state level data for 1970 93 a simultaneous equation model was developed to estimate the direct and indirect effects of different types of government expenditure on ruralpoverty and productivity growth in india the results show that in order to reduce rural poverty the indian government shoul d give highest priority to additionalinvestments in ruralroads and agricul turalresearch these types of investment not only have much larger poverty impacts per rupee spent than any other government investment but also generate higher productivity growth apart from government spending on education which has the third l argest marginalimpact on ruralpoverty and produc

managing supply chain demand variability with scheduled ordering policies this paper studies supply chain demand variability in a model with one supplier and n retailers that face stochastic demand retailers implement scheduled ordering policies orders occur at fixed intervals and are equal to some multiple of a fixed batch size a method is presented that exactly evaluates costs previous research demonstrates that the supplier s demand variance declines as the retailers order intervals are balanced i e the same number of retailers order each period this research shows that the supplier s demand variance will generally decline as the retailers order interval is lengthened or as their batch size is increased lower supplier demand variance can certainly lead to lower inventory at the supplier this paper finds that reducing supplier demand variance with scheduled ordering policies can also lower total supply chain costs

spatial price transmission and asymmetry in the ghanaian maize market abstract this paper utilizes recently developed threshold cointegration tests that allow for asymmetric adjustment toward a long run equilibrium relationship to examine price linkages between principal maize markets in ghana unlike previous studies the approach employed here assumes that economic agents only act to move the system back to equilibrium when the deviation from equilibrium exceeds a critical threshold whereby the benefits of this adjustment exceed the costs the findings indicate that major maize markets in ghana are well integrated both the threshold cointegration and asymmetric error correction models reveal that wholesale maize prices in local markets accra and bolgatanga respond more swiftly to increases than to decreases in central market techiman prices accra prices are found to react faster than bolgatanga prices to changes in techiman market prices

spatial integration at multiple scales rice markets in madagascar the dramatic increase in the price of rice and other commodities over the past year has generated new interest in how these markets work and how they can be improved this article uses an exceptionally rich data set to test the extent to which markets in madagascar are integrated across space at different scales of analysis and to explain some of the factors that limit spatial arbitrage and price equalization within a single country we use rice price data across four quarters of 2000 2001 along with data on transportation costs and infrastructure availability for nearly 1 400 communes in madagascar to examine the extent of market integration at three different spatial scales subregional regional and national and to determine whether non integration is due to high transfer costs or lack of competition the results indicate that markets are fairly well integrated at the subregional level and that factors such as high crime rates remoteness and lack of information are among the factors limiting competition

a theory of commodity price fluctuations this paper studies the price fluctuations of storable commodities that are traded in open markets and are subject to random shocks to demand or more particularly to supply it relaxes the common assumption that the shocks are identically and independently distributed in favor of temporally dependent and periodic disturbances the existence of a unique stationary rational expectations equilibrium is demonstrated for each of the models analyzed and testable implications of the models are derived an illustrative empirical investigation is then undertaken for the model with periodic disturbances using monthly time series observations for seven commodities over the period 1960 93

modelling trends in food market integration method and an application to tanzanian maize markets abstract pushed by increasing availability of price data and extensive market liberalisation efforts in many developing countries research on food market integration has evolved rapidly over the last two decades empirical methods to measure market integration diverged in two directions on the one hand there is the parity bounds model pbm using a switching regressions technique while on the other hand the use of threshold autoregressive tar models has been proposed this article provides a discussion on the two methods and argues that tar models are better able to capture the dynamics of the arbitrage process underlying interconnected markets furthermore we extend the standard tar model to include a time trend in both the threshold and the adjustment parameter using weekly maize price data on seven selected markets in tanzania we illustrate how both transaction cost and the speed of adjustment have changed during the nineties

food price seasonality in africa measurement and extent everyone knows about seasonality but what exactly do we know this study systematically measures seasonal price gaps at 193 markets for 13 food commodities in seven african countries it shows that the commonly used dummy variable or moving average deviation methods to estimate the seasonal gap can yield substantial upward bias this can be partially circumvented using trigonometric and sawtooth models which are more parsimonious among staple crops seasonality is highest for maize 33 percent on average and lowest for rice 16 percent this is two and a half to three times larger than in the international reference markets seasonality varies substantially across market places but maize is the only crop in which there are important systematic country effects malawi where maize is the main staple emerges as exhibiting the most acute seasonal differences reaching the sustainable development goal of zero hunger requires renewed policy attention to seasonality in food prices and consumption

local impacts of a global crisis food price transmission consumer welfare and poverty in ghana abstract this paper takes a local perspective on global food price shocks by analyzing food price transmission between regional markets in ghana it also assesses the impacts of food price increases on various household groups taking the 2007 2008 global food crisis as an example we show that prices for domestic grain products are highly correlated with world market prices this is true both for products for which ghana is highly import dependent e g rice and the products for which ghana is self sufficient e g maize the econometric results also show that price transmission is high between regional producer markets and markets located in the country s largest cities and the distance between producer and consumer markets and the size of consumer markets matter in explaining the price transmission the welfare analysis for households as consumers shows that the effect of world food prices appears relatively modest for the country as a whole due to relatively diverse consumption patterns within country however the national average hides important regional differences both between regions and within different income groups we find that the poorest of the poor particularly those living in the urban areas are hardest hit by high food prices the negative effect of the food crisis is particularly strong in northern ghana the main explanations for this regional variation in the price effect is the different consumption patterns and much lower per capita income levels in the north of ghana compared to other regions in the country

nontraded food commodity spatial price transmission evidence from the niger millet market using an augmented factor vector autoregressive favar model this study analyzes spatial millet prices transmission in niger our results did not find condition for millet markets integration existence however the granger causality tests and impulse response functions from the estimated short term dynamic as favar model revealed the existence of leading markets whose millet prices affect a maximum number of other regional millet prices while some regions seem to be isolated from trade or information flows furthermore the significance of a shock depends also on the characteristics of the region where it originates in terms of millet demand or supply indicating that the region to target and where the price shock originated matter for the policies success

industrial production volatility and the supply chain abstract the issue of production volatility is important to firms interested in managing their supply chain this paper empirically estimates the volatility of industrial production using the garch and egarch time series models three questions are addressed can volatility be predicted is the effect of unexpected changes in production on volatility asymmetric and how persistent is volatility following a production disturbance the results indicate that production volatility is time varying and can be predicted in the majority of cases examined and that overestimates of production lead to greater increases in volatility than do underestimates

local food prices and international price transmission world food prices spiked in the periods 2007 8 and 2010 11 the impact of these spikes in world food prices on local food prices and thus on local consumers is determined by the food price pass through pass through is defined as the extent to which changes in world food prices lead to changes in local food prices we examine the determinants of variation in food price pass through from global to local consumer prices in a global sample of 147 countries using fao data on world food prices and ilo data on food prices for consumers while market integration matters our study finds that income per capita is the dominant factor explaining cross country variation in pass through of food prices we estimate an elasticity of about 0 3 of pass through with respect to income per capita this means far greater price transmission of food price shocks at the commodity level to final consumers in low income countries than in high income countries the implication is that future swings in world food prices will in particular jeopardize food security in poor countries trade policy measures of market integration also affect the pass through significantly whereas infrastructure and geography measures play no significant role

how larger demand variability may lead to lower costs in the newsvendor problem in this paper we consider the newsvendor problem intuition may lead to the hypothesis that in this stochastic inventory problem a higher demand variability results in larger variances and in higher costs in a recent paper song 1994a has proved that the intuition is correct for many demand distributions that are commonly used in practice such as for the normal distribution function however this paper shows that there exist demand distributions for which the intuition is misleading i e for which larger variances occur in combination with lower costs to characterize these demand distributions we use stochastic dominance relations

competitive storage and commodity price dynamics by buying cheap and selling dear risk neutral commodity speculators can smooth commodity prices and induce serial dependence in price even when none would exist under a simple process of supply and demand commodity prices are variable and strongly positively correlated from one year to the next the variability is often explained by supply factors and the autocorrelation by the activities of speculators we show that this explanation is not consistent with the evidence speculation can substantially increase autocorrelation for prices that are weakly autocorrelated in its absence but not to the high levels that are observed in the data

markov switching estimation of spatial maize price transmission processes between tanzania and kenya we discuss the markov switching vector au toregressive ms var class of nonlinear time series models that can be used to analyze recurring discrete structural changes in time series hamilton s 1989 seminal markov switching ms model of the u s business cy cle triggered considerable interest in the ms approach in economics most empirical appli cations to date have focused on the business cy cle and financial markets but we see potential for ms var models in agricultural economics for example in price transmission analysis in the following we first provide an overview of the ms var framework we then present an illustrative application to maize price trans mission between tanzania and kenya the article closes with a discussion of strengths weaknesses and potential uses of the ms var approach in price transmission analysis

the effects of real and nominal uncertainty on inflation and output growth some garch m evidence in this paper we use garch m methods to test four hypotheses about the effects of real and nominal uncertainty on average inflation and output growth in the united states from 1948 to 1996 we find no evidence that higher inflation uncertainty or higher output growth uncertainty raises the average inflation rate we also find no support for the idea that more risky output growth is associated with a higher average real growth rate our key result is that in a variety of models and sample periods inflation uncertainty significantly lowers real output growth copyright 2000 john wiley sons ltd

evaluating the effectiveness of inter regional trade and storage in malawi s private sector maize markets abstract this paper evaluates the effectiveness of the private sector maize marketing system in malawi using threshold autoregression models two dimensions of maize market performance are evaluated 1 inter regional trade and spatial price transmission and 2 storage and seasonal price relationships in both cases threshold autoregression models which account for nonlinearities predicted by economic theory are applied results indicate that spatial price transmission and seasonal price patterns in private sector maize markets in malawi are generally consistent with long run competitive inter regional trade and storage behavior and that in most cases shocks to long run equilibrium are arbitraged away quickly this suggests the private sector in malawi is generally doing a good job of transporting maize from surplus to deficit regions and smoothing maize consumption between harvests

raising offtake from cattle grazed on natural rangelands in sub saharan africa a transaction cost economics approach farmers in sub saharan africa are constrained by large transaction costs associated with marketing of their livestock however transaction costs are often not taken into account in the analysis of factors hampering the development of livestock marketing in this region this article empirically measures the influence of transaction costs on the offtake from cattle grazed on natural rangelands in uganda the study is based on the monitoring of 696 cattle transactions in three districts of uganda from august 2004 to august 2005 the estimated models suggest that proportional transaction costs represented by the state of roads distance to markets and time taken to reach the market are important variables constraining market participation in order to raise offtake from the national herd it is essential to explicitly address these costs one potential solution is collective action in marketing of livestock in which proportional and fixed transaction costs are reduced and shared among the group members

informal barriers and agricultural trade does monetary integration matter eu enlargement and the recent sovereign debt crisis of euro zone countries have revived the debate around the european monetary union emu in this article we ask how informal barriers to agricultural and food trade have changed since the introduction of the common european currency and whether this evolution can be attributed to monetary integration we focus on the foreign trade of the 11 emu founder countries over a nine year period covering the creation of the emu and find a diminishing marginal trade impact of both information and institutional barriers we find a lower level of trade barriers but cannot attribute this outcome to the introduction to the euro

cross country maize market linkages in africa integration and price transmission across local and global markets in order to study short run price shock propagation we model twenty seven sub saharan africa ssa domestic maize markets within a global vector autoregression framework the main purpose is to fully embed multilateral trade flows as a way to better structure local price transmission dynamics and interdependencies and get a more comprehensive picture of food price shocks propagation we found significant between country market contagion and prompt regional price shock propagation when trade connection exists yet the integration of ssa domestic maize markets within the continent and with global markets remains generally weak furthermore under regular market conditions most local price series appear to be more responsive to regional neighbors than to global shocks

spatial price efficiency in mozambique s post reform maize markets maize zea mays shortages and maize price instability continue to occur in mozambique in spite of policy reforms and great capacity for increased production in northern mozambique this study measured the efficiency of spatial maize price arbitrage in mozambique s post reform period spatial price inefficiency does not seem to explain why food shortages continue to occur in mozambique suggesting nonprice market constraints such as poor infrastructure and poor market institutions as more likely explanations baulch s spatial efficiency test indicated that it is not profitable to ship maize from northern surplus maize regions to southern mozambique records of interregional maize shipments show that indeed grain is not being shipped from the north to the south market liberalization may have improved spatial price efficiency but high transfer costs still limit trade and potential benefits from freeing markets under these circumstances food shortages and price instability are likely to continue

multiple regime spatial price transmission with an application to maize markets in southern africa conventional threshold models of price transmission allow for different speeds of adjustment to equilibria depending on the magnitude of price differentials between markets however these models typically assume only one underlying long run equilibrium price relationship in this article we develop a framework for allowing multiple equilibria and multiple speeds of adjustment with regime separation depending on the magnitude of trade flows between regions rather than the magnitude of price differentials applying this framework to maize price transmission between south africa and zambia shows no transmission during periods of high imports when the government was heavily involved in maize importation but stronger transmission during periods of low imports when the government was not importing copyright 2012 oxford university press