future biodiesel policy designs and consumption patterns in latvia a system dynamics model abstract decarbonisation of transport has become central to european union policy biofuels are expected to represent a substantial part of the overall strategy towards diversifying europe s energy supplies and curbing greenhouse gas emissions in a cost effective way this research deals with the dynamic simulation modeling of a biodiesel market as a part of transportation fuel market and analyses of various policy support instruments on increasing the proportion of biofuel in total transport fuel demand the study is carried out for latvia s road transport sector after it had experienced generous financial support from the government allowing the industry to develop support was abruptly stopped creating stagnation in both biodiesel supply and demand this threatened the national transport policy goals the goal of this research is to find the most effective policy strategies for achieving the national transport policy goals by applying system dynamics modeling to the current market conditions of transport fuels specifically the primary focus of this paper is an attempt to gain insight into the long term dynamic behavior of the biodiesel market in latvia the principal policy tools and mechanisms implemented can be summarized as i state subsidies at different levels and stages i e the biodiesel production sector the agricultural sector and the end consumer sectors ii increasing the excise taxes on fossil fuels iii increasing the share of the biodiesel in the transportation fuel blend the results obtained from model simulations confirm that promoting biofuel acceptance among end users is the primary key issue

conditional production smoothing in the united kingdom and japan this article investigates the possibility of macroeconomic conditional production smoothing of inventory investment in japan and the uk it is argued that both unconditional and conditional variances and covariances can be useful to interpret the time paths of sales and production after sales and production shocks the vector error correction model of sales and production is estimated by the bivariate garch procedure based on the cointegration relationship between these variables in the two countries the relative magnitude of the conditional variances of sales and production is explained in terms of sales anticipation errors the relative importance of sales and production shocks and serial correlation in sales shocks the relation of how the conditional second moment corresponds to business cycle phases is briefly analyzed

transport and low carbon fuel a study of public preferences in spain abstract transport is essential for the control of future greenhouse gas ghg emissions and thus a target for active policy intervention in the future yet social preferences for policies are likely to play an important role in this paper we first review the existing literature on preferences regarding low ghg car fuels but also covering policy instruments and strategies in this area we then present the results of a survey of spanish households aimed at measuring preferences for climate change policies we find a positive willingness to pay wtp in the form of higher car fuel prices for a policy to reduce ghg emissions through biofuels there is however significant heterogeneity in public preferences due to personal motivations accounted for via factor analysis of responses to attitudinal questions and to socio demographic variables

interpreting the great moderation changes in the volatility of economic activity at the macro and micro levels most advanced economies have experienced a striking decline in the volatility of aggregate economic activity since the early 1980s volatility reductions are evident for output and employment at the aggregate level and across most industrial sectors and expenditure categories inflation and inflation volatility have also declined dramatically previous studies offer several potential explanations for this great moderation we review evidence on the great moderation in conjunction with evidence about volatility trends at the micro level we combine the two types of evidence to develop a tentative story for important components of the aggregate volatility decline and its consequences the key ingredients are declines in firm level volatility and aggregate volatility most dramatically in the durable goods sector surprisingly this has occurred without a decline in household consumption volatility and individual earnings uncertainty our explanation for the aggregate volatility decline stresses improved supply chain management particularly in the durable goods sector and less important a shift in production and employment from goods to services we provide evidence that better inventory control made a substantial contribution to declines in firm level and aggregate volatility consistent with this view if we look past the turbulent 1970s and early 1980s much of the moderation reflects a decline in high frequency short term fluctuations while these developments represent efficiency gains they do not imply nor is there evidence for a reduction in economic uncertainty faced by individuals and households

price discovery and learning during the preopening period in the paris bourse before the opening of the paris bourse traders place orders and indicative prices are set this offers a laboratory to study empirically the t tonnement process through which markets discover equilibrium prices since preopening orders can be revised or canceled before the opening indicative prices could be noise we test this against the hypothesis that preopening prices reflect learning early in the preopening the noise hypothesis is not rejected as the opening gets closer the informational content and efficiency of prices increase and the learning hypothesis is not rejected we also propose a gmm based estimate of the speed of learning

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

bounded growth of the bullwhip effect under a class of nonlinear ordering policies abstract this paper analyzes the bullwhip effect in multi echelon supply chains under a general class of nonlinear ordering policies a describing function approach from control theory is used to derive closed form formulas to predict amplification of order fluctuations along the supply chain it is proven that with consideration of nonlinearity in the ordering policy the magnitude of the bullwhip effect will eventually become bounded after growing through the first few stages of the supply chain it is also proven that the average customer demand as well as the demand fluctuation frequency would directly affect the bounded magnitude while the suppliers demand forecasting method has no effect at all for illustration analytical results for a class of order up to policies are derived and verified by numerical simulations the proposed modeling framework holds the promise to not only explain empirical observations but also serve as the basis for developing counteracting strategies against the bullwhip effect

production chains and aggregate output volatility abstract a production chain s aggregate output volatility depends upon a number of factors including the number of firms in a chain the management strategy of the firms the point at which products are differentiated lead times and the persistence of demand shocks the influence of these factors is quantified here with an n firm model of the production chain under pure production to stock pts the firms in the chain respond simultaneously to a demand shock producing a positive covariance across firms that raises aggregate volatility under production to order pto the chain s response to a demand shock is staggered but when demand shocks are persistent there is a catch up effect that raises the volatility of each firm s production above that of a firm that under pts nevertheless pto chains typically exhibit less volatility than pts chains thanks to the covariance effect further simulations demonstrate that the production chain stabilizes as the number of production cycles in an observation period increases

markups aggregation and inventory adjustment in this paper i suggest a unified explanation for two puzzles in the inventory literature first estimates of inventory speeds of adjustment in aggregate data are very small relative to the apparent rapid reaction of stocks to unanticipated variations in sales second estimates of inventory speeds of adjustment in firm level data are significantly higher than in aggregate data the paper develops a multisector model where inventories are held to avoid stockouts and price markups vary along the business cycle the omission of countercyclical markup variations from inventory targets introduces a downward bias in estimates of adjustment speeds obtained from partial adjustment models when the cyclicality of markups differs across sectors this downward bias is shown to be more severe with aggregate rather than firm level data similar results apply not only to inventories but also to labor and prices montercarlo simulations of a calibrated version of the model suggest that these biases are quantitatively significant

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

customer order information leadtimes and inventories we have an inventory to manage the scenario is standard in all respects save one instead of arriving unannounced customers provide advance warning of their demands how should we use this information and what is its effect on system performance the answers turn out to be strikingly simple there are very simple policies which perform effectively in some cases optimally also such demand leadtimes improve performance in precisely the same way that replenishment leadtimes degrade it

understanding the inventory cycle abstract careful examination of aggregate data from the u s and other oecd countries reveals that production and inventory behavior exhibit paradoxical features 1 inventory investment is strongly countercyclical at very high frequencies e g 2 3 quarters per cycle it is procyclical only at relatively low cyclical frequencies such as the business cycle frequencies e g 8 40 quarters per cycle 2 production is less volatile than sales around the high frequencies it is more volatile than sales only around business cycle or lower frequencies 3 unlike capital investment or gdp the bulk of the variance of inventory investment is concentrated around high frequencies rather than around business cycle frequencies these features of production and inventory behavior at the low and high frequencies provide a litmus test for inventory theories this paper shows that the stockout avoidance theory kahn j 1987 inventories and the volatility of production american economic review 77 667 679 has much better potential than other competing theories for explaining the seemingly paradoxical features of inventory fluctuations observed at different cyclical frequencies my analysis suggests that demand shocks are the main source of the business cycle

trading mechanisms and stock returns an empirical investigation this paper examines the effects of the mechanism by which securities are traded on their price behavior we compare the behavior of open to open and close to close returns on nyse stocks given the differences in execution methods applied in the opening and closing transactions opening returns are found to exhibit greater dispersion greater deviations from normality and a more negative and significant autocorrelation pattern than closing returns we study the effects of the bid ask spread and the price adjustment process on the estimated return variances and covariances and discuss the associated biases we conclude that the trading mechanism has a significant effect on stock price behavior

money and the business cycle with one period nominal contracts a modified version of the nominal contract developed by j a gray 1976 and s fischer 1977 is introduced in a general equilibrium model with money which has been used in the real business cycle literature money is introduced in the model through cash in advance constraint two kinds of contracts are examined namely a nominal wage contract and a nominal price contract the nominal wage contract improves the fit of the model in many respects the nominal price contract increases the output volatility enormously but it has some unrealistic features

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

avoiding the bullwhip effect using damped trend forecasting and the order up to replenishment policy we study the damped trend forecasting method and its bullwhip generating behaviour when used within the order up to out replenishment policy using z transform transfer functions we determine complete stability criteria for the damped trend forecasting method we show that this forecasting mechanism is stable for a much larger proportion of the parametrical space than is generally acknowledged in the literature we provide a new proof to the known fact that the naive exponential smoothing and holts method forecasting when used inside the out policy will always generate bullwhip for every possible demand process for any lead time further we demonstrate the damped trend out system behaves differently sometimes it will generate bullwhip and sometimes it will not bullwhip avoidance occurs when demand is dominated by low frequency harmonics in some instances in other instances bullwhip avoidance happens when demand is dominated by high frequency harmonics we derive sufficient conditions for when bullwhip will definitely be generated and necessary conditions for when bullwhip may be avoided we verify our analytical findings with a numerical investigation

taking stock a critical assessment of recent research on inventories empirical and theoretical aspects of inventory behavior became hot topics in the 1950s and early 1960s no one seemed to notice the tension that was developing between the emerging macroeconomic and microeconomic views of inventories macroeconomists routinely thought of inventories as a destabilizing factor yet the prevailing micro theory viewed inventories as a stabilizing factor it was a fascinating question that was barely explored instead somewhat inexplicably interest in inventories dried up as if inventories were of minor economic significance and little intrinsic interest by the early 1980s then economists once again knew something they had known in the 1950s that inventory investment is of first order importance in business cycles but they were also beginning to realize that the standard production smoothing buffer stock model of inventories was in deep trouble this paper focuses on developments since that realization

uncertainty in sales and inventory behaviour in the u s trade sectors this paper investigates uncertainty in sales and inventory behavior for the u s wholesale and retail trade sectors first using a vector error correction model with garch m the authors find that the uncertainty measured by forecast error variance in sales does not affect inventory behavior in both trade sectors second using forecast error variance decomposition and estimated permanent components they observe that the uncertainty may be attributed more to demand shocks than to cost shocks

production sales and the change in inventories an identity that doesn t add up we examine two measures of monthly manufacturing production the first is the index of industrial production the second is constructed from the accounting identity that output equals sales plus the change in inventories we show that the means variances and serial correlation coefficients of the log growth rates differ substantially between the two series and the cross correlations are in most cases less than 0 4 a model of classical measurement error indicates that in 15 of 20 two digit industries measurement error accounts for over 35 of the variation in the monthly growth rates of seasonally adjusted industrial production

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

volume volatility and new york stock exchange trading halts trading halts increase rather than reduce both volume and volatility volume volatility in the first full trading day after a trading halt is 230 percent 50 to 115 percent higher than following pseudohalts nonhalt control periods matched on time of day duration and absolute net of market returns these results are robust over different halt types and news categories higher posthalt volume is observed into the third day while higher posthalt volatility decays within hours the extent of media coverage is a partial determinant of volume and volatility following both halts and pseudohalts but a separate halt effect remains after controlling for the media effect in the wake of the 1987 market break a number of commentators including the presidential task force on market mechanisms recommended the establishment of circuit breaker mechanisms the primary argument supporting circuit breakers both price limits and trading halts is that nontrading periods provide an opportunity for normal information transmission in times of market duress proponents of circuit breakers claim that during major price changes there can be a breakdown in the transmission of information between the trading floor and market participants therefore the primary function of a circuit breaker should be to reinform participants greenwald and stein 1988 p 17 by lowering informational asymmetries between traders halts could permit the orderly emergence of a new consensus price but would informative trading halts succeed many academics are openly suspicious of any kind of market interference and assume that trading halts are guilty until proven innocent grossman 1990 p 3 for example argues that the closing of markets merely prevents consenting adults from carrying out their desires on the floor of the stock exchange not only do halts impose a liquidity cost on traders but studies suggest that information will not be as

production smoothing in the linear quadratic inventory model contrary to popular belief the linear quadratic inventory model does not imply that in response to demand shocks output is always less variable than sales when demand shocks are not anticipated and without this assumption it is hard to see why firms should hold inventories in the first place it is shown that output can be more variable than sales even when the only shocks are demand shocks and the inventory target is not a rising function of sales the variance of output will typically exceed that of sales when the firm s marginal cost curve is fairly flat copyright 1994 by royal economic society

public acceptance of biofuels abstract the public acceptance of biofuels in greece is examined in this work the analysis of 571 face to face interviews shows that 90 7 of the respondents believe that climatic changes are related to fossil fuel consumption while only 23 8 know the difference between biodiesel and bioethanol 76 1 believe that energy saving should precede the use of an alternative source of energy only 27 3 believe that priority must be given to biofuels over other renewable energy sources only 49 9 think that the use of biofuels can be an effective solution against climatic changes and 53 9 believe that the use of biofuels can be an effective solution for the energy problem finally 80 9 of the car owners are willing to use biofuels 44 8 are willing to pay the supplementary amount of 0 06 l of the fuel market price while the average amount reported as willing to pay was 0 079 l on top of the fuel market price furthermore eight models correlating the eight main responses with several socioeconomic variables are developed and analyzed those findings heave important policy implications related to the use and promotion of biofuels

the switch from continuous to call auction trading in response to a large intraday price movement some european exchanges e g euronext frankfurt and madrid make use of a mechanism to moderate price volatility that was proposed by madhavan 1992 as preferable to a trading halt in times of market stress it consists of a temporary switch from continuous to call auction trading in an individual security whenever its price moves beyond predetermined limits this article studies whether this mechanism sharpens the information content of prices dampens volatility and normalizes trading volume and intensity taking intraday data for the madrid order driven continuous market i find post switch improvements in the information content of prices and reductions in volatility especially for thinly traded stocks trading volume and intensity peaked around auctions but soon returned to preevent levels

promoting renewable energy sources for heating and cooling in eu 27 countries abstract in addition to public policies aimed at improving the energy efficiency of buildings eu authorities have also promoted the use of renewable energy sources for heating and cooling uses res h c this paper analyses the main policy measures implemented in eu 27 countries up to 2009 i e subsidies tax incentives financial support and feed in tariffs twenty three member states mss have developed some of these policy measures the most widespread measure is the subsidy 22 mss have implemented these because from a political point of view subsidies provide a straightforward approach to promote the use of res h c secondly tax incentives have been used for reducing investment costs and making renewable energy profitable thirdly financial incentives and feed in tariffs have been used sparingly while financial incentives might be used more extensively for promoting res h c if they are accompanied by other policy measures feed in tariffs are not likely to be implemented significantly in the future because this measure is not designed for household heat producers

the linear quadratic inventory model as a micro foundation for keynesian theories of the business cycle abstract aggregate inventory investment is invariably procyclical this suggests that inventories play a destabilizing role in the economy as predicted by early keynesian models of the business cycle however this behavior is believed to be inconsistent with the most prominent micro theory of inventories the linear quadratic model this is not the case the linear quadratic model when placed in a simple macro framework can account for the procyclical behavior of inventory investment even when the only shocks are independent demand shocks inventory targets are independent of sales and individual firms adjust inventories slowly towards their target levels

the effect of information sharing on supply chain stability and the bullwhip effect this paper analyzes the bullwhip effect in multi stage supply chains operated with linear and time invariant inventory management policies and shared supply chain information such information includes past order sequences and inventory records at all supplier stages the paper characterizes the stream of orders placed at any stage of the chain when the customer demand process is known and ergodic and gives an exact formula for the variance of the orders placed the paper also derives robust analytical conditions based only on inventory management policies to predict the presence of the bullwhip effect and bound its magnitude these results hold independently of the customer demand the general framework proposed in this paper allows for any inventory replenishment policies any ways of sharing and utilizing information and any customer demand processes it is also shown as a special case that sharing customer demand information across the chain significantly reduces but does not completely eliminate the bullwhip effect

the production and inventory behavior of the american automobile industry understanding inventory movements is central to an understanding of business cycles this paper presents an empirical study of the behavior of inventories in the automobile industry it finds that inventory behavior is well explained by the assumption of intertemporal optimization with rational expectations the underlying cost structure appears to have substantial costs of changing production as well as substantial costs of being away from target inventory thelatter being a function of current sales given this cost structure whether inventory behavior is stabilizing or destabilizing depends on the characteristics of the demand process in the automobile industry inventory behavior is destabilizing the variance of production is larger than the variance of sales

order flow and liquidity around nyse trading halts we study order f low and liquidity around nyse trading halts we find that market and limit order submissions and cancellations increase significantly during trading halts that a large proportion of the limit order book at the reopen is composed of orders submitted during the halt and that the market clearing price at the reopen is a good predictor of future prices depth near the quotes is unusually low around trading halts though specialists and0or f loor traders appear to provide additional liquidity at these times finally specialists appear to spread the quote prior to imbalance halts to convey information to market participants the costs and benef its associated with new york stock exchange trading halts are the subject of continuous debate the stated purpose of trading halts is to allow investors a chance to react to new information and to facilitate the orderly emergence of a new equilibrium price see e g nyse 1999 however little is known about the extent or nature of investor reactions to trading halts furthermore it is unclear whether these reactions support or confound attempts to reach a new equilibrium price to address these issues we use nonpublic nyse data on all superdot electronic orders to analyze the effects of trading halts on order f low spreads and the limit order book we also examine the relationships between the limit order book and the reopening price and between liquidity and post halt volatility information on order f low is an important missing element in the ongoing debate about the usefulness of trading halts one argument against trading halts is that they impede price formation because trading aggregates information that is distributed across market participants however submissions and cancellations of orders during a halt may provide an alternative source of information that combined with published indications of possible reopening prices may assist with price formation an argument in favor of trading halts is that when traders are given an opportunity to cancel orders

a measure of bullwhip effect in supply chains with a mixed autoregressive moving average demand process abstract in this paper we quantify the impact of the bullwhip effect the phenomenon in which information on demand is distorted as moving up a supply chain for a simple two stage supply chain with one supplier and one retailer assuming that the retailer employs a base stock inventory policy and that the demand forecast is performed via a mixed autoregressive moving average model arma 1 1 we investigate the effects of the autoregressive coefficient the moving average parameter and the lead time on the bullwhip effect

the role of retailer s performance in optimal wholesale price discount policies abstract the main goal of this paper is to model the effects of wholesale price control on manufacturer s profit taking explicitly into account the retailer s sales motivation and performance we consider a stylized distribution channel where a manufacturer sells a single kind of good to a single retailer wholesale price discounts are assumed to increase the retailer s motivation thus improving sales we study the manufacturer s profit maximization problem as an optimal control model where the manufacturer s control is the discount on wholesale price and retailer s motivation is one of the state variables in particular in the paper we prove that an increasing discount policy is optimal for the manufacturer when the retailer is not efficient while efficient retailers may require to decrease the trade discounts at the end of the selling period computational experiments point out how the discount on wholesale price passed by the retailer to the market pass through influences the optimal profit of the manufacturer

value of information in capacitated supply chains we incorporate information flow between a supplier and a retailer in a two echelon model that captures the capacitated setting of a typical supply chain we consider three situations 1 a traditional model where there is no information to the supplier prior to a demand to him except for past data 2 the supplier knows the s s policy used by the retailer as well as the end item demand distribution and 3 the supplier has full information about the state of the retailer order up to policies continue to be optimal for models with information flow for the finite horizon the infinite horizon discounted and the infinite horizon average cost cases study of these three models enables us to understand the relationships between capacity inventory and information at the supplier level as well as how they are affected by the retailer s s s values and end item demand distribution we estimate the savings at the supplier due to information flow and study when information is most beneficial

what do inventories tell us about news driven business cycles there is widespread disagreement over the quantitative contribution of news shocks to business cycle fluctuations this paper provides a simple identifying restriction based on inventory dynamics that tightly pins down this contribution structural models predict that finished good inventories should fall when there is an increase in consumption and investment induced by news shocks a structural var with these sign restrictions indicates that news shocks account for at most 20 percent of output volatility since inventories comove positively with consumption and investment in the data shocks that generate negative comovement cannot account for the bulk of fluctuations

tax incentives to promote green electricity an overview of eu 27 countries this paper provides a comprehensive overview of the main tax incentives used in the eu 27 member states mss to promote green electricity sixteen mss use tax incentives to promote green electricity simultaneously with other promotion measures especially quota obligations and price regulation however not all available technologies are promoted for example six mss germany romania slovak republic denmark sweden and poland have included an exemption on the payments of excise duties for electricity when the electricity is generated from renewable energy sources res this tax incentive is the most widely used limited tax incentives in personal income tax are available in belgium france czech republic and luxembourg in corporate tax tax incentives consist mainly of a deduction in the taxable profit belgium greece czech republic and spain lower tax rates in vat are applied in three mss france italy and portugal only spain and italy use effective tax incentives in property tax as a great diversity of tax incentives has been used to promote green electricity this adds another difficulty to the eu objective of providing a renewable energy policy framework but also it offers a useful set of case studies which can be used to inform eu policy development

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 exact analytical solution to the production inventory control problem abstract the full set of continuous differential delay equations describing the inventory and orders for a typical industrial production control system are solved exactly for a step function surge in demand the replenishment delay is explicitly included the order rate is tuned with three parameters which modulate the demand smoothing the recovery of the inventory deficit and the desired level of work in process the analytical solutions are validated by comparison with numerical integration and confirm the instabilities and inventory deficits found elsewhere useful management strategies can be deduced and the approach should be widely applicable in supply chains

modeling and analysis of cash flow bullwhip in supply chain abstract the bullwhip effect that occurs in supply chain inventory can distort demand forecasts and lead to inefficiencies such as excessive inventory stock outs and backorders in this paper we theorize that inventory bullwhip also leads to cash flow bullwhip cfb specifically this paper focuses on studying cfb by developing mathematical and simulation models to analyze the relationship between inventory and cash flow bullwhip by using cash conversion cycle ccc as a metric the mathematical models for inventory bullwhip are developed for two stage and generic multi stage supply chains and then by extending these inventory models the cfb models are developed for two stage cfb predicted by the proposed mathematical models approximately differ 14 from detailed simulation models we find that increasing variability increases inventory and cash flow bullwhip along with lead time whereas increasing the demand observation period has the opposite effect the average marginal impact of the bullwhip effect on the cfb is approximately 20 additionally the cfb is also an increasing function of an expected value of inventory and a decreasing function of an expected value of demand

nonconvex costs and the behavior of inventories this paper explores one possible explanation for the apparent excess volatility of production relative to sales nonconvexities in the technology facing firms it is shown that if firms operate in a region of declining marginal costs then small shifts in demand can cause production to jump substantially estimates for six production to stock industries as well as the automobile industry suggest that all these industries behave as if they were operating in the region of nonconvex costs the results have important implications not only for inventory investment but also for the cyclical behavior of productivity and prices

the bullwhip effect in supply chain networks this paper analyzes the propagation and amplification of order fluctuations i e the bullwhip effect in supply chain networks operated with linear and time invariant inventory management policies the supply chain network is allowed to include multiple customers e g markets any network structure with or without sharing information the paper characterizes the stream of orders placed by any supplier for any stationary customer demand processes and gives exact formulas for the variance of the orders placed and the amplification of order fluctuations the paper also derives robust analytical conditions based only on inventory management policies to predict the presence of the bullwhip effect for any network structure any inventory replenishment policies and arbitrary customer demand processes numerical examples show that the analytical results accurately quantify the bullwhip effect managerial insights are drawn from the analysis the methodology presented in this paper generalizes those in previous studies for serial supply chains

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

biofuel support policies in europe lessons learnt for the long way ahead biofuel consumption in the eu is growing rapidly but major efforts will need to be undertaken if the eu s objectives for 2010 and beyond are to be achieved this article analyses the strengths and weaknesses of different biofuel support policies based on the experiences gained in pioneering countries and explores scenarios for their possible impacts in the long term it comes to the conclusion that important pre conditions such as fuel standards and compatibility with engines are in place or being introduced on an eu wide basis current and future policy support therefore focuses on creating favourable economic or legal frameworks to accelerate the market penetration of biofuels the ambitious targets endorsed in terms of biofuel market shares require the implementation of efficient policy instruments at the same time large consumption volumes and the advent of innovative production technologies make it possible for member states to promote specific types of biofuels depending on their main objectives and natural potentials this will require complementary instruments such as subsidies for production facilities user incentives or feedstock subsidies

stock market structure and volatility the procedure for opening stocks on the nyse appears to affect price volatility an analytical framework for assessing the magnitude of the structurally induced volatility is presented the ratio of variance of open to open returns to closeto close returns is shown to be consistently greater than one for nyse common stocks during the period 1982 through 1986 tbe greater volatility at the open is not attributable to the way in which public information is released since both the opento open return and the close to close return span the same period of time instead the greater volatility appears to be attributable to private information revealed in trading and to temporaryprice deviations induced by specialist and other traders the implied cost of immediacy at the open is significantly higher than at the close other empirical evidence in this article documents the volume of trading at the open the time delays between the exchange opening and the first transaction in a stock the difference in daytime volatility versus overnight volatility and the extent to which volatility is related to trading volume

stock market microstructure and return volatility evidence from italy abstract this paper studies the impact of the stock market microstructure on return volatility and on the value discovery process in the milan stock exchange the primary trading mechanism employed by this exchange is a call market which is usually preceded and followed by trading in a continuous market we find that the opening transaction in the continuous market has the highest volatility and that opening the market with the call transaction seems to produce relatively lower volatility in the closing transaction investors correct perceived errors or noise in the prices set at the call the implications of the results for market design are examined

the production impact of cash for clunkers implications for stabilization policy during july and august of 2009 americans purchased nearly 700 000 new automobiles or light trucks under the government s cash for clunkers program officially the car allowance rebate system or cars under the terms of the purchase qualified buyers traded in their old vehicles to receive a rebate on the price of a new vehicle the amount of the rebate either 3 500 or 4 500 depended on both the model that was traded in and the model that was acquired the direct cost to taxpayers of subsidizing these purchases was roughly 2 8 billion the program had two primary goals to reduce energy consumption and pollution by inducing consumers to replace their old gas guzzlers with newer fuel efficient models and to serve as a stimulus for the troubled automobile industry and the u s economy as a whole in this article we take a close look at the second objective exploring how the cars program affected sales and more important production in the automobile industry 1 drawing on our findings we then propose an answer to the more difficult question of the program s impact on u s gross domestic product gdp 2 in line with other recent studies our analysis shows that the cars program had only a transitory cumulative effect on sales we estimate an initial impact of about 450 000 additional automobile sales but these were essentially shifted from the periods before and especially after the program we calculate that by january 2010 the cumulative effect of the cars program on auto sales was essentially zero 3 more important for our purposes however is the program s effect on automobile production while most studies of cars have focused on sales we argue that the program s success as a stimulus to the economy hinges on its impact on production production increases are more likely to translate into higher gdp and employment gdp being fundamentally a measure of production sales clearly rose at the outset but given that the industry can simply let inventory stocks absorb the increase in sales higher sales alone do not imply higher gdp or employment 4 overall we find that the program had a very modest and short lived effect on production production was about 200 000 units higher during the program in comparison to the 450 000 increase in sales sales from september 2009 to january 2010 were correspondingly lower than they would have been in the absence of cars which allowed producers to have lower production while still replenishing their inventory stocks thus on a quarterly basis we estimate that the cars program shifted production by around 100 000 units from 2009q4 and 2010q1 to 2009q3 these calculations suggest that the program had a negligible direct effect on gdp shifting less than roughly 2 billion or less than one tenth of 1 of gdp into 2009q3 from the subsequent two quarters this contrasts starkly with a study released by the department of transportation dot in the immediate aftermath of the program which concluded that cars had given a substantial boost to both gdp and employment in the final section of the article we discuss why our conclusions differ from those of the dot study our findings raise broader questions beyond just this particular program about the efficacy of efforts to stimulate short term spending it is clearly a mistake to gauge their impact by just looking at the spending they induce without looking at the supply side it is reasonable to expect that producers will use other margins than production and employment to respond to temporary movements in sales so the only question is quantitative how large is the gap between the sales and production impact we find it to be large in the case of cash for clunkers in what follows we will lay out the economics behind our analysis by examining how rebates and other transitory price changes affect consumer purchases and manufacturers inventory decisions

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

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

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

inventories inflation dynamics and the new keynesian phillips curve abstract we introduce inventories into an otherwise standard new keynesian model and study the implications for inflation dynamics inventory holdings are motivated as a means to generate sales for demand constrained firms we derive various representations of the new keynesian phillips curve with inventories and show that one of these specifications is observationally equivalent to the standard model with respect to the behavior of inflation when the model s cross equation restrictions are imposed however the driving variable in the new keynesian phillips curve real marginal cost is unobservable and has to be proxied by for instance real unit labor cost an alternative approach is to impute marginal cost by using the model s optimality conditions we show that the stock sales ratio is linked to marginal cost we also estimate these various specifications of the new keynesian phillips curve using gmm we find that the predictive power of the inventory specification at best approaches that of the standard model but does not improve upon it

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

the impact of information enrichment on the bullwhip effect in supply chains a control engineering perspective this paper examines the beneficial impact of information sharing in multi echelon supply chains we compare a traditional supply chain in which only the first stage in the chain observes end consumer demand and upstream stages have to base their forecasts on incoming orders with an information enriched supply chain where customer demand data e g epos data is shared throughout the chain two types of replenishment rules are analysed order up to out policies and smoothing policies policies used to reduce or dampen variability in the demand for the class of out policies we will show that information sharing helps to reduce the bullwhipeffect variance amplification of ordering quantities in supply chains significantly especially at higher levels in the chain however the bullwhip problem is not completely eliminated and it still increases as one moves up the chain for the smoothing policies we show that information sharing is necessary to reduce order variance at higher levels of the chain the methodology is based on control systems engineering and allows us to gain valuable insights into the dynamic behaviour of supply chain replenishment rules we also introduce acontrolengineering based measure to quantify the variance amplification bullwhip or variance reduction

production smoothing evidence from physical product data we reconsider the paradox that the variance of production often exceeds the variance of shipments a result that casts doubt on the production smoothing model of inventory behavior most studies of production smoothing have analyzed two digit sic dollar value data from commerce department surveys in contrast this paper examines disaggregated physical product data and finds that production is smoother than shipments in about two thirds of the 38 industry or product groupings considered however doubts about the model persist most notably euler equation estimates of the model s cost parameters are usually imprecise and often do not have the signs postulated by production smoothing models

price limit performance evidence from the tokyo stock exchange price limit advocates claim that price limits decrease stock price volatility counter overreaction and do not interfere with trading activity conversely price limit critics claim that price limits cause higher volatility levels on subsequent days volatility spillover hypothesis prevent prices from efficiently reaching their equilibrium level delayed price discovery hypothesis and interfere with trading due to limitations imposed by price limits trading interference hypothesis empirical research does not provide conclusive support for either positions we examine the tokyo stock exchange price limit system to test these hypotheses our evidence supports all three hypotheses suggesting that price limits may be ineffective

an empirical investigation of dynamic ordering policies adaptive base stock policy is a well known tool for managing inventories in nonstationary demand environments this paper presents empirical tests of this policy using aggregate firm level data first we extend a single item adaptive base stock policy in previous literature to a multi item case second we transform the policy derived for the multi item case to a regression model that relates firm level inventory purchases to firm level sales and changes in sales forecasts we focus on two research questions can the adaptive base stock policy explain cross sectional ordering behaviors under sales growth to the extent that the adaptive base stock policy fails to explain ordering behaviors under sales growth are there frictions that explain such a finding our empirical results demonstrate disparities in ordering behaviors between firms experiencing high and moderate sales growth contrary to theoretical prediction this implies that inventory purchases are a function of not only current sales and changes in sales forecast but also past sales growth as potential explanations for this departure from theoretical prediction we show that both future demand dynamics and inventory holding risks depend on past sales growth in addition we find that firms inventory holding risks may also be affected by purchasing constraints imposed by supply chain contracts our results provide managerial implications for practitioners and inform future theoretical research this paper was accepted by martin lariviere operations management

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 panel data study on spanish firms inventory investment this paper raises several questions about inventory investment of a sample of 172 big nonfinancial spanish companies inventory investment has been usually explained by two alternative theories the production smoothing model and the s s model first we provide a descriptive analysis based on industry level data to show some shortcomings of the first model then we test a flexible accelerator model using firm level data the results seem to show that inventory investment previous period inventories and sales are closely and significantly related this evidence although not conclusive rejects both the pure production smoothing model and the s s model at the same time our results confirm the view of a target inventory level and the plausibility of the so called stock adjustment model so that the optimal inventory holding buffers sales volatility

the existence of pareto superior price limits this paper examines the welfare effects of futures price limits under a simple form of market incompleteness when prices become volatile shocks to liquidity and fundamentals may occur between the time investors decide to trade and the time their orders are executed this gives rise to implementation risk that cannot be transferred with contingent claims we show that price limits partially insure implementation risk hhen price fluctuations are driven by news about fundamentals judiciously chosen price limits can be ex ante pareto superior to unconstrained trade when liquidity shocks are large price limits benefit hedgers but harm some speculators jel d60 g20

inventories and the automobile market this article studies the within model year pricing production and inventory management of new automobiles using new monthly data on u s transaction prices we document that for the typical vehicle prices fall over the model year at a 9 0 annual rate concurrently both sales and inventories are hump shaped to explain these time series we formulate an industry model for new automobiles in which inventory and pricing decisions are made simultaneously the model predicts that automakers build to stock inventory management policy substantially influences the time series of prices and sales accounting for four tenths of the price decline observed over the model year

the production smoothing model of inventories revisited an error correction specification which nests the linear quadratic production smoothing and stock adjustment models of inventories is estimated on u s seasonally adjusted two digit sic data the restrictions of the general model to the production smoothing specification is accepted for four out of six of the production to stock industries and for total nondurables the estimation results do not suggest any use of inventories to smooth the level of production but there is evidence of smoothing of the rate of change of production for three production to stock industries and for both total nondurables and total durables coefficient estimates may however be biased copyright 1994 by royal economic society

the bullwhip effect in capacitated supply chains with consideration for product life cycle aspects abstract this paper presents an analysis of the bullwhip effect and net stock amplification in a three echelon supply chain considering step changes in the production rates during a product s life cycle demand the analysis is focused around highly complex and engineered products e g automobiles that have relatively long production life cycles and require significant capital investment in manufacturing using a simulation approach we analyze three stages of the product life cycle including low volumes during product introduction peak demand and eventual decline toward the end of the life cycle parts of the simulation model have been adopted by a major north american automotive oem as part of a scenario analysis tool for strategic supply network design and analysis the simulation results show that performance of a system as a whole deteriorates when there is a step change in the life cycle demand while restriction in production capacity does not significantly impact the bullwhip effect it increases the net stock amplification significantly for the supply chain setting under consideration furthermore a number of important managerial insights are presented based on sensitivity analysis of interaction effect of capacity constraints with other supply chain parameters

governance and legitimacy aspects of the uk biofuel carbon and sustainability reporting system biofuel policy has become highly contentious in europe in this paper we discuss the governance and legitimacy aspects of the carbon and sustainability system of the uk renewable transport fuel obligation rtfo both before and after implementation of the renewable energy directive rtfo certification is of a meta type being built upon existing certification and labelling schemes each of which are more or less contested by ngos despite the rtfo being based on these non state initiatives so far the concerns of environment and development ngos and others have not been given serious expression in regulatory terms indeed biofuel policy development in the uk has arguably been unduly non responsive to critical opinion given the limited scientific base on biofuel impacts and the reliance of rtfo sustainability certification on non state actors and schemes drawing on documentary evidence interviews and three sets of literatures co production of regulation post normal science and legitimacy of non state certification and labelling processes we suggest that until concerned voices are given a stronger expression in uk and ec biofuel policy development the policy cannot yet be said to have achieved a wide social mandate

european union leadership in biofuels regulation europe as a normative power the rapid emergence of the european union eu as a leader in global environmental politics has led many scholars to argue in favour of the eu being a normative power in international relations this paper critically examines the eu s biofuels policy and evaluates whether its attempts to lead by example and shape international practice in this field could support such arguments europe s biofuel policies are evaluated through a sustainable development lens so as to determine the extent to which it has embraced a holistic approach to sustainability while not dismissing that the identity of the eu is indeed an explanatory factor and that normative intentions may well be regarded as a motivating force this study argues that an interest based perspective on international environmental regulation offers a supplementary view of how an actor s preferences for an international regime are shaped by erecting barriers aimed at shielding its own inefficient domestic biofuels production the eu is in essence placing trade competitiveness and economic growth above environmental protection thus permitting sustainability concerns to be addressed only in part

interest rates and the market for new light vehicles we study the impact of interest rates changes on both the demand for and supply of new light vehicles in an environment where consumers and manufacturers face their own interest rates an increase in the consumers interest rate raises their cost of financing and thus lowers the demand for new vehicles an increase in the manufacturers interest rate raises their cost of holding inventories both channels have equilibrium effects that are amplified and propagated over time through inventories which serve as a way to both smooth production and facilitate greater sales at a given price through the estimation of a dynamic stochastic market equilibrium model we find evidence of both channels at work and of the important role played by inventories a temporary 100 basis point increase in both interest rates causes vehicle production to fall 12 percent and sales to fall 3 25 percent at an annual rate in the short run

promotion of biofuel consumption in the transport sector an eu 27 perspective abstract the european union s eu directive 2003 30 ec 1 set an objective of reaching a 5 75 share of renewable energy as a proportion of the total energy consumption of the transport sector by 2010 as all the member states mss of the eu 27 were obliged to comply with this directive different public policy measures were developed and implemented to promote the use of biofuels in transport biofuels being the main renewable energy source res in this sector in this article we review the public measures undertaken in the eu 27 and show how these measures primarily involve tax incentives and biofuel blending mandates on fuel sales all countries with the exception of finland introduced tax incentives of various types to promote the use of biofuels while 18 mss also implemented biofuel blending mandates through the passing of legislation relating to this matter

measure of bullwhip effect in supply chains with autoregressive demand process abstract in supply chain management one of the most critical problems which require a lot of effort to deal with is how to quantify and alleviate the impact of bullwhip effect the phenomenon in which information on demand is distorted while moving upstream although it is well established that demand forecast lead time order batching shortage gaming and price fluctuation are the main sources that lead to the bullwhip effect the problem of quantifying bullwhip effect still remain unsolved in many situations due to the complex nature of the problem in this research a measure of bullwhip effect will be developed for a simple two stage supply chain that includes only one retailer and one supplier in the environment where the retailer employs base stock policy for their inventory and demand forecast is performed through the first order autoregressive model ar 1 the effect of autoregressive coefficient and lead time on this measure will then be investigated

price formation on stock exchanges the evolution of trading within the day prior analyses of prices of the nyse and other exchanges find that transitory price volatility is greater at the open of trading than at the close we extend this line of research by using 40 years of hourly dow jones 65 composite price index data to estimate transitory volatility throughout the trading day our results indicate that transitory volatility steadily declines during the trading day we find a similar intraday decline in transitory volatility for a 2 1 2 year sample of the individual firms in the dow jones 30 industrials index the results are consistent with the hypothesis that trading aids price formation and do not support the argument that particular trading mechanisms are the source of greater volatility at the open of trading article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

a closing call s impact on market quality at euronext paris abstract the paris bourse currently euronext paris refined its trading system to include electronic call auctions at market closings in 1996 for its less liquid continuous b stocks and in 1998 for its more actively traded continuous a stocks this paper analyzes the effects of the innovation on market quality our empirical analysis of price behavior for two samples of firms 50 b stocks and 50 a stocks for two different calendar dates 1996 and 1998 indicates that introduction of the closing calls has lowered execution costs for individual participants and sharpened price discovery for the broad market we further observe that market quality is improved at market openings albeit to a lesser extent we suggest that a positive spillover effect explains the closing call s more pervasive impact

bullwhip effect measurement and its implications the bullwhip effect or demand information distortion has been a subject of both theoretical and empirical studies in the operations management literature in this paper we develop a simple set of formulas that describe the traditional bullwhip measure as a combined outcome of several important drivers such as finite capacity batch ordering and seasonality our modeling framework is descriptive in nature as it features certain plausible approximations that are commonly employed in practical inventory systems the results are nonetheless compelling and can be used to explain various conflicting observations in previous empirical studies building on the theoretical framework we discuss the managerial implications of the bullwhip measurement we show that the measurement can be completely noninformative about the underlying supply chain cost performance if it is not linked to the operational details such as decision intervals and leadtimes specifically we show that an aggregated measurement over relatively long time periods can mask the operational level bullwhip in addition we show that masking also exists under product or location aggregation in some illustrative cases

equilibrium adjustment with endogenous information and inventories the paper analyzes the interaction of information acquisition and inventory flexibility with industry adjustment to imperfectly perceived cost and demand disturbances improved information about disturbances reduces the extent to which disturbances are unperceived and dampens the use of inventories reduced inventory flexibility induces firms to devote more resources to acquiring information about disturbances the analysis demonstrates how equilibrium price and output adjustment depend endogenously on the degree of inventory flexibility and other structural parameters influencing the acquisition of information in this paper we analyze how endogenous information acquisition and inventory flexibility influence price and output adjustment in a competitive industry we focus on the potential substitutability of information acquisition for inventory flexibility when disturbances are imperfectly perceived by individual firms the analysis highlights the general issue of how market adjustment depends on structural parameters that influence agents incentives to acquire information there are several reasons why information acquisition may play a role in market adjustment first the rapid development of information technology has enabled firms to gather and process data relevant to production and sales decisions from a greater number of external and internal sources this trend has reduced the costs of forecasting and monitoring factors influencing production and demand conditions for the individual firm relative to those of its competitors as well as for the industry as a whole in particular it has permitted quicker awareness of changing customer demand as well as greater control of the flow of inputs and intermediate goods during the production process this implies that the resources devoted to information acquisition and processing have come to play an important role in firm decisions 2 second improved information about demand and cost conditions may affect the function of inventories inventory adjustment allows a firm s production costs to be smoothed in response to anticipated movements in demand and costs and to be buffered against unanticipated disturbances see ashley and orr 1985 thus

can the production smoothing model of inventory behavior be saved the production smoothing model of inventory behavior has a long and venerable history and theoretical foundations that seem very strong yet certain overwhelming facts seem not only to defy explanation within the production smoothing framework but actually to argue that the basic idea of production smoothing is all wrong most prominent among these is the fact that the variance of detrended production exceeds the variance of detrended sales this paper first documents the stylized facts then it derives the production smoothing model rigorously and explains how the model can be amended to make it consistent with the facts finally it reviews the theoretical and empirical evidence and tries to draw some tentative conclusions

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

financing constraints and inventories abstract this paper investigates the impact of financing constraints on firms inventory and cash management in particular it examines the extent to which the presence of such constraints may account for certain empirical regularities these include e g the excess variance of production vis a vis that of sales as well as the counter cyclicality and persistence of the inventory sales ratio we model the intertemporal decision making on production cash retention and dividends of a firm that is exposed to stochastic demand shocks in every period and faces constrained access to external sources of finance it is found that the presence of financing constraints can explain the excess variance of production in a model which otherwise would not deliver this result moreover as long as demand is positively serially correlated they also contribute to the counter cyclicality and persistence of the inventory sales ratio the paper suggests that financing constraints should not be discarded as a factor driving the cyclical behaviour of inventories