behavioral causes of the bullwhip effect and the observed value of inventory information the tendency of orders to increase in variability as one moves up a supply chain is commonly known as the bullwhip effect we study this phenomenon from a behavioral perspective in the context of a simple serial supply chain subject to information lags and stochastic demand we conduct two experiments on two different sets of participants in the first we find the bullwhip effect still exists when normal operational causes e g batching price fluctuations demand estimation etc are removed the persistence of the bullwhip effect is explained to some extent by evidence that decision makers consistently underweight the supply line when making order decisions in the second experiment we find that the bullwhip and the underlying tendency of underweighting remains when information on inventory levels is shared however we observe that inventory information helps somewhat to alleviate the bullwhip effect by helping upstream chain members better anticipate and prepare for fluctuations in inventory needs downstream these experimental results support the theoretically suggested notion that upstream chain members stand to gain the most from information sharing initiatives

learning by doing the technology gap and growth in contrast with other trade and growth theories in previous literature the author resents a growth theory of trade induced learning other things being equal two conditions are essential for trade induced learning first both exports and imports are equally important sources and are mutually reinforced in intensifying the learning process moreover the nature or characteristics of these traded goods also influence the effect of learning second trade openness is a prerequisite but not a sufficient condition for rapid growth with whom one trades one s trading partner is a key factor in determining trade induced technology spillover and hence in affecting enduring growth therefore this trade induced learning theory provides abundant and testable implications for the empirical study of trade and growth copyright 1998 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

portfolio optimisation and the design of latin american export diversification policies this article applies portfolio optimisation analysis to assess the risk and return characteristics of commodity export structures of selected countries in latin america the analysis is conducted both for the export structure of traditionally exported commodities and for the non traditional agricultural commodities that are being promoted as part of recent export diversification efforts in these countries the results show that portfolio optimisation analysis can provide a valuable tool for the improvement of the risk return properties of various export structures

concentration diversification and earnings instability some evidence on developing countries exports of manufactures and primary products policies aimed at diversification of the commodity composition of exports continue to be advocated as a means of reducing instability in ldcs export earnings the usual assumptions are that earnings from manufactures are more stable than earnings from primary products and that diversification will reduce the covariances between earnings from different pairs of products it is suggested here that for several reasons these assumptions may not be valid evidence is then presented which indicates that across a sample of countries diversification has taken place but has not been accompanied by relatively greater stability in manufactures and favourable changes in covariances

commodity price instability and economic goal attainment in developing countries abstract this paper reviews the theoretical and empirical micro and macro foundations for the frequent claims that instabilities in international commodity markets have deleterious effects on goal attainment in primary commodity exporting developing countries this review leads to the conclusion that the available evidence does not support these claims the paper concludes with speculation on why such claims are so strong despite the lack of supporting evidence perhaps it is because of measurement problems and perhaps because of small but articulate groups with vested interests in overstating the problem

what does export diversification do for growth an econometric analysis it is frequently suggested that export diversification contributes to an acceleration of growth in developing countries horizontal export diversification into completely new export sectors may generate positive externalities on the rest of the economy as export oriented sectors gain from dynamic learning activities due to contacts with foreign purchasers and exposure to international competition vertical diversification out of primary into manufactured exports is also associated with growth since primary export sectors generally do not exhibit strong spillovers yet there have been remarkably few empirical investigations into the link between export diversification and growth this paper attempts to examine the hypothesis that export diversification is linked to economic growth via externalities of learning by doing and learning by exporting fostered by competition in world markets the diversification led growth hypothesis is tested by estimating an augmented cobb douglas production function on the bas

analysis of compound bullwhip effect causes abstract this research investigates compound causes of the bullwhip effect bwe by considering an inventory system with multiple price sensitive demand streams joint price and demand dynamics are captured by a vector time series process that incorporates the stochastic co movements in price and demand we study two bwe measures one for each demand stream individually and one for the aggregated demand we show that demand parameters including demand autocorrelation cross correlation and price sensitivity serve as root causes of the bwe we prove that the impact of these parameters on the bwe can be additively decomposed conditions are established under which a pair of simultaneous compound causes may attenuate or dampen the bwe when demand streams are aggregated we derive a pooling factor that quantifies the impact of demand aggregation on order stability when positive the pooling factor corresponds to a synergy effect that captures the gain in the stability of the pooled orders conditions for the existence of the synergy effect are obtained for several special cases involving a zero leadtime we also discuss how our analytical findings can be managerially applied to bullwhip mitigation strategies

providing a measure for bullwhip effect in a two product supply chain with exponential smoothing forecasts abstract in this paper a two product and two echelon supply chain is considered in order to quantify the bullwhip effect demands of the products are correlated and are represented by a first order vector autoregressive model retailer uses order up to ordering policy for replenishment of stocks and utilizes exponential smoothing forecast method to predict demand in lead time period according to the mentioned assumptions an equation is derived for bullwhip effect measurement and then a numerical example is presented for a better perception of the bullwhip effect behavior when the parameters change a comparison of the bullwhip effect measure has been done when two main forecasting methods i e exponential smoothing and moving average are used and empirical results are provided at last a cost analysis is conducted based on shortage and holding cost under different bullwhip effect measures

export product diversification and co2 emissions contextual evidences from developing and developed economies abstract ascertaining cleaner production and sustainability is a major issue in the developed and developing world income and international trade are the predominant factors behind this this article explores the heterogeneous impacts of export product diversification extensive margin and intensive margins on the co2 emissions for developing and developed countries to this end the authors analyze the annual data of variables from 1971 to 2014 and employ unrestricted fixed effects and system gmm to solve the research problem the empirics suggest that all three indicators of export diversification significantly reduce co2 emissions in 63 developed and developing countries as a global sample the fixed effect models reveal that product diversification and intensive margin have a negative and significant impact in developed economies the negative impacts of product diversification show that economic sophistication is an important tool to reduce emissions further the chow test proved the statistical difference between developed and developing economies which contributes to policy recommendations based on the empirical outcomes the study suggests innovative policies for cleaner production and industrial manufacturing purposes making the policies more effective in achieving sustainable development goals sdgs

a time series framework for supply chain inventory management we consider a supply chain in which the underlying demand process can be described in a linear state space form inventory is managed at various points of the chain members based on local information that each member observes and continuously updates the key feature of our model is that it takes into account the ability of the members to observe subsets of the underlying state vector and adopt their forecasting and replenishment policies accordingly this enables us to model situations in which the members are privy to certain explanatory variables of the demand with the latter possibly evolving according to a vector autoregressive time series for each member we identify an associated demand evolution model for which we propose an adaptive inventory replenishment policy that utilizes the kalman filter technique we then provide a simple methodology for assessing the benefits of various types of information sharing agreements between members of the supply chain we also discuss inventory positioning and cost performance assessment in the supply chain our performance metrics and inventory target levels are usually presented in matrix forms allowing them to accommodate a relatively large spectrum of linear demand models and making them simple to implement several illustrations for possible applications of our models are provided

the role of manufacturing in regional growth harris r i d 1987 the role of manufacturing in regional growth reg studies 21 301 312 since a shift in regional policy away from manufacturing to aiding services is being advocated this paper re examines the role of manufacturing in regional growth from both an empirical and theoretical viewpoint first of all it discusses the importance of manufacturing s share of output concluding that in output terms and prior to 1979 manufacturing has not been displaced by services in shares of total output secondly the paper focuses on the theoretical importance of manufacturing to the growth of regional output showing that for most theories demand side growth pole cumulative causation manufacturing is the natural base for growth potential harris r i d 1987 le role des industries de fabrication dans la croissance regionale reg studies 21 301 312 vu que l on propose une reorientation de la politique regionale au depens des industries de fabrication et en faveur du tertiaire cet article

industry risk factors and the implications for diversification within the northern ireland regional economy this discussion attempts to identify within the northern ireland regional framework risk factors beta coefficients for all industrial classifications both private and public sector the stability of these risk factors over a recent 25 year period and their response to cyclical fluctuations in the regional economy are examined before they are employed as input data in the construction of an optimal diversified industrial portfolio for norhern ireland the study indicates that the classifications with in the service sector both private and public exhibit below average employment variability and that the optimal industrial base in northern ireland in terms of minimizing employment variability is one of a relatively heavy reliance on service sector industries and in particular producer services such a finding is important in that it lends support to those advocating an expansion of producer services at the regional level on the basis that producer services like manufacturing add to the stock of weal

manufactured exports and terms of trade of developing countries evidence from sri lanka terms of trade implications of diversification into manufactured exports in a traditional primary exporting country are examined in the light of the sri lankan experience over the past two decades the empirical analysis focuses on trends in both commodity and income terms of trade employing a methodology which takes care of the spurious regression problem the results suggest that contrary to the new terms of trade pessimism export diversification has brought about significant terms of trade gains for the sri lankan economy overall the study casts doubt on the robustness of results coming from analyses of price trends in aggregate manufactured exports and calls for systematic time profile analyses of the countries which have achieved significant export diversification in order to inform the policy debate

the stabilizing effect of inventory in supply chains this paper presents a hierarchical model framework for the analysis of the stabilizing effect of inventories in multiechelon manufacturing distribution supply chains this framework is used to compare the variance of demand to the variance of replenishment orders at different echelons of the system e g retailer wholesaler empirical data and experience with management games suggest that in most industries inventory management policies can have a destabilizing effect by increasing the volatility of demand as it passes up through the chain the bullwhip effect our model helps to explain these observations and indicates mechanisms that can promote stabilization the analysis results also define sufficient conditions for the existence of stabilization and relate these conditions to the optimality of myopic control policies

the impact of foreign direct investment on horizontal export diversification empirical evidence using data on stocks of foreign direct investment fdi from 131 countries spanning the years 1984 to 2004 and the number of products exported by each country we examine the effect of fdi on horizontal export diversification to quantify the effects we utilize parametric quantile and semi parametric econometric methods results from both approaches indicate that in general an increase in the stock of fdi enhances the horizontal diversification of exports the actual magnitude of the effect however varies greatly across countries depending on the existing stock of fdi and stage of diversification giving rise to an almost inverted u shaped relationship a further look at our results provides useful insights on the circumstances under which fdi may aid or inhibit the horizontal expansion of exports

the disappearing gay income penalty abstract since 1995 labor economists have reported on the income disparities between individuals who engage in same sex behavior and those that do not many of these papers report a significant wage penalty while others find no effect but few look at the trend over time we find using national health and examination survey nhanes data from 1988 to 2007 that the income gap has reversed over time from a penalty to a premium

contracting and information sharing under supply chain competition we investigate contracting and information sharing in two competing supply chains each consisting of one manufacturer and one retailer the two supply chains are identical except they may have di

the sexual orientation wage gap the role of occupational sorting and human capital using data from the 2000 u s census the authors explore two alternative explanations for the sexual orientation wage gap occupational sorting and human capital differences they find that lesbian women earned more than heterosexual women irrespective of marital status while gay men earned less than their married heterosexual counterparts but more than their cohabitating heterosexual counterparts results of a oaxaca blinder decomposition indicate that the relative wage advantages observed for some groups of lesbians and gay men were mainly owing to greater levels of human capital accumulation particularly education while occupational sorting had little or no influence the relative wage penalties that were observed in other cases however cannot be attributed either to differences in occupational sorting or to human capital an analysis employing a dinardo fortin and lemieux decomposition which allows for variation in the wage gap at different points along the wage distribution broadly confir

product diversification and stability of employment and sales first evidence from german manufacturing firms we use a unique rich newly built data set for german manufacturing enterprises to investigate the relationship between product diversification and the stability of sales and employment we find that contrary to portfolio theoretic considerations more diversified firms exhibit a higher variability of sales and employment however the effects are negligibly small from an economics point of view

commodity concentration and export earnings instability a shift from cross section to time series analysis conventionally commodity concentration has been regarded as a major factor contributing to the short term instability in earnings experienced by developing countries the repeated and unexpected lack of correspondence between the conventional view and results of empirical studies has generated attempts to identify the limitations of the customary analytical framework this paper attempts to derive a more satisfactory alternative framework application of this alternative approach to export data for a sample of developing countries produces results which in contrast to the evidence of previous studies indicate the widespread existence of a statistically significant positive relationship between concentration and export instability

want export diversification educate the kids first this paper uses bayesian model averaging to uncover the true determinants of export diversification among 36 potential factors and thus 236 potential models using data from 2001 to 2010 our results reveal two strong predictors primary school enrollment 99 7 posterior inclusion probability in the true model raises export diversification whereas the share of natural resources in gross domestic product 98 6 lowers diversification levels the importance of basic education coverage offers policymakers an opening toward diversifying exports at least in the long run this result is robust to accounting for the endogeneity of income levels by applying an instrumental variable bma method jel c11 f1 f34 o1 o2 o11

information sharing and order variability control under a generalized demand model the value of information sharing and how it could address the bullwhip effect have been the subject of studies in the literature most of these studies used different forms of demand models assuming that no order smoothing was used by the retailer and that the supplier has full knowledge of the retailer s demand model and order policy in this paper we contribute to the literature by starting with a most general demand model coupled with a smoothing policy for order variability control in addition we do not require that the supplier has full knowledge of the retailer s demand model and order policy but instead let the retailer share its projected future orders and freely revise them as the retailer sees fit under such a setting we first obtain a unifying formula for the magnitude of the bullwhip effect the formula indicates that it is the forecast correlation over the exposure period as a whole that determines the magnitude of the bullwhip effect we then quantify the value of information sharing and generalize the existing results in the literature finally we explore the optimal smoothing parameters that could benefit the total supply chain the resulting optimal policy resembles the postponement strategy we find that information sharing together with order postponement improves the supply chain performance even though the order variability may amplify in some cases

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

an arima supply chain model this paper presents a multistage supply chain model that is based on autoregressive integrated moving average arima time series models given an arima model of consumer demand and the lead times at each stage it is shown that the orders and inventories at each stage are also arima and closed form expressions for these models are given the paper also discusses the causes of the bullwhip effect a phenomenon in which variation in demand produces larger variations in upstream orders and inventory this discussion reveals how different modeling can lead to different insights because they make different assumptions about the cause of the bullwhip effect these observations are used to develop managerial insights about reducing the bullwhip effect

analysis of the bullwhip effect in two parallel supply chains with interacting price sensitive demands abstract this paper offers insights into how the bullwhip effect in two parallel supply chains with interacting price sensitive demands is affected in contrast to the situation of a single product in a serial supply chain in particular this research studies two parallel supply chains each consisting of a manufacturer and a retailer and the external demand for a single product depends on its price and the other s price in a situation in which each price follows a first order autoregressive process in this paper we propose an analytical framework that incorporates two parallel supply chains and we explore their interactions to determine the bullwhip effect we identify the conditions under which the bullwhip effect is amplified or lessened with interacting price sensitive demands relative to the situation without interaction

research on bullwhip effect in energy efficient air conditioning supply chain abstract this paper investigates the energy efficient air conditioning supply chain which is composed of one supplier midea and two retailers i e suning and gome with a view of market share we measure the impact of retail prices variability in the two echelon supply chain on the bullwhip effect suning and gome are assumed to possess the autonomy of choosing prices and separately acquire various market shares according to which the relationship between the two prices is simply quantified the order up to inventory policy and the moving average forecasting method are respectively employed by the two retailers furthermore we cast light on how factors like price market share lead time and autoregressive coefficient affect bullwhip effect the results indicate that it s inadvisable to conduct large fluctuation on price besides demand dates that are more historical may actually reduce the bullwhip effect we also find that the bullwhip effect will be bigger when the competition becomes fiercer and there s a necessity for retailers to take measures to reduce the influence of competitors prices

sharing demand information in competing supply chains with production diseconomies this paper studies the incentive for vertical information sharing in competing supply chains with production technologies that exhibit diseconomies of scale we consider a model of two supply chains each consisting of one manufacturer selling to one retailer with the retailers engaging in cournot or bertrand competition for cournot retail competition we show that information sharing benefits a supply chain when 1 the production diseconomy is large and 2 either competition is less intense or at least one retailer s information is less accurate a supply chain may become worse off when making its information more accurate or production diseconomy smaller if such an improvement induces the firms in the rival supply chain to cease sharing information for bertrand retail competition we show that information sharing benefits a supply chain when 1 the production diseconomy is large and 2 either competition is less intense or information is more accurate under bertrand competition a manufacturer may be worse off by receiving information which is never the case under cournot competition information sharing in one supply chain triggers a competitive reaction from the other supply chain and this reaction is damaging to the first supply chain under cournot competition but may be beneficial under bertrand competition this paper was accepted by martin lariviere operations management

export specialisation and local economic growth this paper aims to provide empirical evidence on whether export specialization or diversification is better for local economic growth using export data from 354 magisterial districts of south africa for 1996 and 2001 we estimate spatial growth regressions that include measures of the degree of export specialization and diversification overall exporting regions outperform other less or non exporting regions also we find that export specialisation rather than export diversification has been associated with local economic growth with specialization in mining and agriculture being especially beneficial our results support the view that specialization in a locality s area of comparative advantage is good for local economic development we also find that localities with higher initial levels of human capital and higher subsequent population growth performed better this is consistent with the belief that policies aimed at strengthening human capital and improving agglomeration economies will enhance local economic development

portfolio models and planning for export diversification malawi tanzania and zimbabwe evidence is presented regarding strengths and limitations of portfolio approaches as applied to diversifying export earnings an empirical application using data from malawi tanzania and zimbabwe is used to demonstrate these strengths and limitations modifications of the typical portfolio approach to export diversification are presented these modifications help make the approach more plausible for use in developing countries the modified approach is shown to provide guidance to policymakers who seek simultaneously to increase export earnings and reduce their instability

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

conditions of reverse bullwhip effect in pricing under joint decision of replenishment and pricing abstract a reverse bullwhip effect in pricing rbp occurs when an amplification of price variability takes place moving from the upstream suppliers to the downstream customers in a supply chain in this study we investigate rbp conditions for supply chains where joint replenishment and pricing decisions are made commencing with a single stage supply chain in which a retailer faces a random and price sensitive demand we extend the results to a multi stage supply chain using a leader follower game theoretical framework we discuss rbp conditions for supply chains where newsvendor and continuous review inventory policies are employed and present numerical examples for commonly used demand functions

an investigation into sexual orientation discrimination as an explanation for wage differences this study explores the effects of sexual orientation on earnings it is found that ceteris paribus men living with male partners tend to earn less than other men and women living with female partners tend to earn more than other women these earnings differentials tend to vary by region they also vary by education and occupation for men and with the presence of minor children for women in addition the age earnings profiles of women living with female partners tend to be higher flatter and less concave than those of other women

reverse bullwhip effect in pricing price variability is one of the major causes of the bullwhip effect this paper analyzes the impact of procurement price variability in the upstream of a supply chain on the downstream retail prices procurement prices may fluctuate over time for example when the supply chain players deploy auction type procurement mechanisms or if the prices are dictated in market exchanges a game theory framework is used here to model a serial supply chain sequential price game scenarios are investigated to show that there is an increase in retail price variability and an amplified reverse bullwhip effect on prices rbp under certain demand conditions

a new look at the benefits of diversification lessons from central america recent trends of export diversification in central america may lower foreign exchange earnings instability there four countries costa rica el salvador honduras and guatemala are analysed across a twenty year period the paper uses united nations commodity trade statistics to explain why costa rica and honduras have enjoyed greater earnings stability in recent years despite the fact that honduras has not greatly diversified its export products and markets despite the growth of new agricultural and manufacturing goods traditional primary products still dominate the countries export portfolios specific products within each of the four broad product category groups contribute to the varied country outcomes summary statistics from the united nations panel data suggest newer agricultural exports have not stabilized guatemalan and salvadoran export earnings while honduras has enjoyed relatively stable banana export revenues and costa rica has benefited from the smooth flow of microelectronic product

currency of denomination and the measurement of export instability the widespread and unexpected absence of statistically significant relationships in analyses of the causes and consequences of export instability has generated attempts to refine measurement of variable sets recently it has been suggested that country rankings are sensitive to the choice of currency numeraire this article investigates the significance of the choice of numeraire for a sample of 66 developing countries the results suggest that the conventional approach of denominating export earnings in terms of us dollars is not seriously deficient and that the selection of an appropriate form of trend correction remains an important consideration

on the stability of supply chains this paper examines the stability of decentralized multistage supply chains under arbitrary demand conditions it looks for intrinsic properties of the inventory replenishment policies that hold for all customer demand processes and for policies with desirable properties it is found that the overall conditions experienced by suppliers several stages removed from the final customer e g the variances of the orders they receive and the inventories they keep depend on the policy much more than on the demand process a policy specific but demand independent upper bound for the order variance amplification factor of any decentralized policy is shown to exist and its formula is presented the bound is always tight for the suppliers at the end of a long chain so that a policy exhibits the bullwhip effect if and only if its bound is greater than 1 a simple necessary condition for bullwhip avoidance is also identified in terms of a policy s gain gain is the marginal change in average inventory induced by a policy when there is a small but sustained change in the demand rate it is shown thatall policies with positive gain produce the bullwhip effect if they do not use future order commitments because manufacturers can reduce costs by operating with positive gain this explains the prevalence of the bullwhip effect a family of commitment based policies that can dynamically maintain any desired inventory level for any demand rate e g achieve positive gain without the bullwhip effect is also presented the family includes just in time strategies as a special case simulation results are used as an illustration

coordinating lead times and safety stocks under autocorrelated demand we consider a supply chain in which orders and lead times are linked endogenously as opposed to assuming lead times are exogenous this assumption is relevant when a retailer s orders are produced by a supplier with finite capacity and replenished when the order is completed the retailer faces demands that are correlated over time either positively or negatively which may for example be induced by a pricing or promotion policy the auto correlation in demand affects the order stream placed by the retailer onto the supplier and this in turn influences the resulting lead times seen by the retailer since these lead times also determine the retailer s orders and its safety stocks which the retailer must set to cover lead time demand there is a mutual dependency between orders and lead times the inclusion of endogenous lead times and autocorrelated demand represents a better fit with real life situations however it poses some additional methodological issues compared to assuming exogenous lead times or stationary demand processes that are independent over time by means of a markov chain analysis and matrix analytic methods we develop a procedure to determine the distribution of lead times and inventories that takes into account the correlation between orders and lead times our analysis shows that negative autocorrelation in demand although more erratic improves both lead time and inventory performance relative to iid demand positive correlation makes matters worse than iid demand due to the endogeneity of lead times these effects are much more pronounced and substantial error may be incurred if this endogeneity is ignored

a new look at the effects of export instability on investment and growth abstract this paper is concerned with the effects of export instability on investment and growth it is shown that past cross sectional empirical studies on the effects of export instability either in prices or in value terms used an incorrect measure of instability that does not properly take account of the share of exports in gdp using a new instability index and a broad set of conditioning variables it is shown that export instability was positively associated with investment but negatively associated with growth in a large sample of countries during the period from the early 1970s to the mid 1980s

export instability an alternative analysis of causes numerous studies into the causes of the export instability experienced by developing countries have failed to establish any significant relationships this paper suggests that the widely used technique of cross country regression analysis is inappropriate and that the typical explanatory variable set is inadequately specified accordingly analysis is shifted to a time series basis at the level of individual countries and explanatory variables are developed which correspond more closely to the supply and demand determinants of instability applying this alternative model to data for a sample of developing countries produces results which suggest that this approach has considerable explanatory power

the bullwhip effect on inventory a perspective on information quality abstractin recent years there has been a vast increase in the quantity of information shared across supply chain we investigate how the timeliness and accuracy of information quality affect the value of information sharing we use the inventory bullwhip effect bwe to measure the value of information sharing in a two level supply chain consisting of one retailer and one manufacturer the retailer faces a price sensitive demand and the price is an ar 1 process our study shows if customer demand and retailer s immediate order are delayed using retailer s historical order quantity to forecast can decrease manufacturer s bwe if information errors happen during delivery and utilization information sharing is not always valuable for the manufacturer sometimes no information sharing can decrease much more of bwe if information errors occur when the retailer collects demand information value of information sharing is more significant than when there are no information errors

risk analysis with single index portfolio models an application to farm planning sharpe s 1963 single index portfolio model the separation theorem and a solution method suggested by elton gruber and padberg are adapted in this paper to the farm diversification problem the objectives are to develop risk measures based on single index parameters and computationally simple methods for farm risk planning that are suitable for microcomputers and modern hand held calculators the intent is to produce a normative model with possible extension applications

male female wage differentials and policy responses without implicating them for any of the contents of the paper i am grateful to the following for helpful discussions or comments andrea beller university of illinois david bloom harvard and columnbia glen cain university of wisconsin ron ehrenberg cornell victor fuchs stanford bob gregory australian national university jonathan leonard university of california berkeley roberta robb brock university and paul weiler harvard financial support of the humanities and social sciences committee of the research board of the universitu of toronto is eratefullu acknowlede ed

variety complexity and economic development abstract we propose a combinatorial model of economic development an economy develops by acquiring new capabilities allowing for the production of an ever greater variety of products with an increasing complexity taking into account that economies abandon the least complex products as they develop over time we show that variety first increases and then decreases in the course of economic development this is consistent with the empirical pattern known as the hump our results question the common association of variety with complexity we further discuss the implications of our model for future research

characterization of the bullwhip effect in linear time invariant supply chains some formulae and tests the authors analyze the bullwhip effect in multistage decentralized supply chains operated with linear and time invariant inventory management policies the focus is on robustness the supply chain is modeled as a single input single output control system driven by arbitrary customer demands the authors derive robust analytical conditions to predict the presence of the bullwhip effect and bound its magnitude based only on the way inventories are managed these results hold independently of the customer demand the authors also characterize the stream of orders placed at any stage of the chain when the customer demand process is known and ergodic and give an exact formula for the variance of the orders placed this formula generalizes existing results by broadening the class of inventory replenishment policies and customer demand processes to which it applies the authors also show that the bullwhip effect can be mitigated by introducing commitments for future orders into the ordering policies

measuring and avoiding the bullwhip effect a control theoretic approach an important contributory factor to the bullwhip effect i e the variance amplification of order quantities observed in supply chains is the replenishment rule used by supply chain members first the bullwhip effect induced by the use of different forecasting methods in order up to replenishment policies is analysed variance amplification is quantified and we prove that the bullwhip effect is guaranteed in the order up to model irrespective of the forecasting method used thus when production is inflexible and significant costs are incurred by frequently switching production quantities up and down order up to policies may no longer be desirable or even achievable in the second part of the paper a general decision rule is introduced that avoids variance amplification and succeeds in generating smooth ordering patterns even when demand has to be forecasted the methodology is based on control systems engineering and allows important insights to be gained about the dynamic behaviour of replenishment rules