a simple heuristic for joint inventory and pricing models with lead time and backorders we study a joint inventory and pricing problem in a single stage system with a positive lead time we consider both additive and multiplicative demand forms this problem is in general intractable due to its computational complexity we develop a simple heuristic that resolves this issue the heuristic involves a myopic pricing policy that generates each period s price as a function of the initial inventory level and a base stock policy for inventory replenishment in each period the firm monitors its so called price deflated inventory position and places an order to reach a target base stock level the price deflated inventory position weights the on hand and pipeline inventory according to a factor that reflects the sensitivity of price to the net inventory level to assess the effectiveness of our heuristic we construct an upper bound to the exact system the upper bound is based on an information relaxation approach and involves a penalty function derived from the proposed heuristic a numerical s

is it time to split the s p 500 futures contract by october 1996 the value of the s p 500 index futures contract had grown to five times its value at its inception in april 1982 one way to make the contract more accessible to small investors and to smooth out trading is to split the contract splitting the contract could increase transaction costs although competition would probably limit the amount of the increase less clear is the need for increasing the minimum percentage tick size the current minimum tick size is small for s p 500 futures compared with that of other futures and also common stocks the larger tick size could affect volume however by increasing trading costs and reducing the willingness to trade

on measures of excess burden and their application abstract new measures of the additional excess burden of a tax reform are proposed and are shown to be useful in three key policy applications these new measures induce a unique measure of marginal excess burden meb among its interesting properties meb is uniformly zero for a proportional tax on inelastically supplied labor problems in applying the standard measures of total excess burden are demonstrated it is concluded that the induced measure of the marginal cost of funds mcf should be regarded as the most useful concept in applied tax analysis

aggregate earnings and gross domestic product international evidence abstractrecent studies in macro accounting suggest that changes in aggregate accounting earnings can predict quarterly gdp growth in the usa our objective in this study is to test the robustness o

integrating replenishment decisions with advance demand information there is a growing consensus that a portfolio of customers with different demand lead times can lead to higher more regular revenues and better capacity utilization customers with positive demand lead times place orders in advance of their needs resulting inadvance demand information this gives rise to the problem of finding effective inventory control policies under advance demand information we show that state dependent s s and base stock policies are optimal for stochastic inventory systems with and without fixed costs the state of the system reflects our knowledge of advance demand information we also determine conditions under which advance demand information has no operational value a numerical study allows us to obtain additional insights and to evaluate strategies to induce advance demand information

information quality and market efficiency the purpose of this paper is to analyze the optimal individual behavior in acquiring infor mation and to determine the amount of information incorporated in a stock at equilibrium in the presence of a cost schedule in acquiring information our paper shows that at equi librium the cost to acquire information that is not already incorporated in the price de pends only on the representative investor s risk preferences it follows that the marginal information costs are the same across all stocks at equilibrium even though the stock s information costs schedules may differ this suggests that the prices of small stocks may not incorporate all publicly available information this paper also provides empirical evi dence that newspapers publication of publicly available information can affect the stock prices

temperature shocks and the cost of equity capital implications for climate change perceptions financial market information can provide an objective assessment of losses anticipated from temperature changes in an apt model in which temperature shocks are a systematic risk factor the risk premium is significantly negative loadings for most assets are negative and asset portfolios in more vulnerable industries have stronger negative loadings on a temperature shock factor weighted average increases in the cost of equity capital attributed to uncertainty about temperature changes are 0 22 percent implying a present value loss of 7 92 percent of wealth these costs represent a new channel that may contribute to cost of climate change assessment

price reforms in the power sector the world bank s role this paper discusses whether the world bank s bank s policy has been successful in promoting economic efficiency in the power sector the conclusion is that the bank s presence has improved the situation as four countries receiving a disproportionate share of bank assistance have witnessed a more positive development since the late 1980s than developing countries as a whole loans provided through periods of non compliance may have eased the urgency of reform in a longer perspective the financing of such over investment may have been justified on grounds of maintaining the bank s presence in these countries and laying the foundation for the more recent sector reforms co ordination with broader sector reforms is also found to yield positive results

speculative prices and popular models t he rational expectations revolution in economics was born of the recognition that the expectations people hold for future economic variables are fundamental to their behavior thus our economists economic models require their those who make up the economy economic models models which they use to generate their expectations the key idea of rational expectations models is to collapse the two models into one to assume that people know or behave as if they know the true model that describes the economy this idea allows economists to construct simple and elegant models of the economy models that are appealing theoretically and that can be studied without collecting any data about the models in the minds of economic actors the problem with the rational expectations models is that collapsing the two kinds of models into one is a gross oversimplification obviously the popular models the models that are used by the broad masses of economic actors to form their expectations are not the same as those held by economists once one accepts the difference economic modelling cannot proceed without collecting data on the popular models themselves this paper reports on such a data collection effort on popular models using questionnaire survey methods with the purpose of understanding speculative markets i will report here on my research to understand the u s stock market crash of october 1987 research fumiko konya yoshiro tsutsui and i undertook to understand the japanese stock market crash of october 1987 research karl case and i undertook to understand recent real estate booms and research john pound and i undertook to understand the periodic hot markets for initial public offerings ipo s of common stock

conversation information and herd behavior experimental evidence shows that an important reason why people tend to imitate others to exhibit herd behavior is that they assume that the others have information that justifies their actions the information cascade models of banerjee 1992 and bikhchandani et al 1992 are significant developments in showing some general equilibrium and welfare effects of such rational imitative behavior but these models as specified may be of limited applicability since they assert that differences across groups in herd behavior can be attributed to the random decisions of first movers differences across groups in herd behavior might be explained more often in terms of different modes of interpersonal information transmission patterns of human conversation imply great selectivity to the kinds of information transmitted within groups this abstract was borrowed from another version of this item

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

analyzing the analysts career concerns and biased earnings forecasts this paper examines the career concerns of security analysts we relate long histories of their earnings forecasts to job separations we find that relatively accurate past forecasts lead to favorable career outcomes such as remaining at or moving up to a high status large prestigious brokerage house controlling for accuracy optimistic forecasts relative to the consensus increase the chances of favorable job separations job separations depend much less on accuracy for analysts who cover stocks that are underwritten by their brokerage houses such analysts are also much more likely to be rewarded for optimistic forecasts than other analysts furthermore job separations were much less sensitive to accuracy and somewhat more sensitive to optimism during the stock market mania of the late 1990s these findings suggest that the well documented analyst forecast optimism bias is likely due to incentives to promote stocks

does the sun shine on art prices this paper examines how variation in mood influences subjective risk and hence auction prices for art in london during the period 1990 2007 the private value of an object is closely related to taste and mood which is proxied for by the variation in weather using a unique data set that includes presale estimates for paintings sold through sotheby s and christie s auction houses as well as weather data for london from the british atmospheric data centre we find that the lower part of the price distribution is populated with paintings with a relative high private value whereas in the upper part prices are driven primarily by the common value characteristics our findings have important implications for collectors and investors in the art market

information sharing in supply chains an empirical and theoretical valuation we provide an empirical and theoretical assessment of the value of information sharing in a two stage supply chain the value of downstream sales information to the upstream firm stems from improving upstream order fulfillment forecast accuracy such an improvement can lead to lower safety stock and better service based on the data collected from a consumer packaged goods company we empirically show that if the company includes the downstream sales data to forecast orders the improvement in the mean squared forecast error ranges from 7 1 to 81 1 across all studied products theoretical models in the literature however suggest that the value of information sharing should be zero for over half of our studied products to reconcile the gap between the literature and the empirical observations we develop a new theoretical model whereas the literature assumes that the decision maker strictly adheres to a given inventory policy our model allows him to deviate accounting for private information held by the decision maker yet unobservable to the econometrician this turns out to reconcile our empirical findings with the literature these decision deviations lead to information losses in the order process resulting in a strictly positive value of downstream information sharing furthermore we empirically quantify and show the significance of the value of operations knowledge the value of knowing the downstream replenishment policy this paper was accepted by serguei netessine operations management

market efficiency bounded rationality and supplemental business reporting disclosures the aicpa special committee on financial reporting has urged disclosure of relevant forward looking information on risks and opportunities to supplement conventional financial statements we conduct a laboratory market experiment to assess the effects of such disclosures on capital allocation decisions we develop two sets of competing hypotheses regarding how capital markets react to supplemental disclosures one set is based on the assumption of semi strong market efficiency while the other posits that the bounded rationality of individual traders leads to inefficient market prices we find that explicit disclosure of management s best estimate of an uncertain quantity improves market efficiency even though this disclosure is redundant with information in financial statements second we find disclosure of an upper bound of management s estimate has the potential to bias security prices upward while informationally equivalent disclosure of both upper and lower bounds removes this bias these results suggest that experimental market reactions to these supplemental disclosures are inconsistent with market efficiency supplemental analyses of individuals price predictions and trading behavior support our conclusion that inefficiencies are at least partially attributable to individual information processing biases

global value chains and trade elasticities we investigate whether global value chains have increased the sensitivity of chinese trade to foreign income shocks this may occur through either composition or supply chain effects we find evidence for the former but not the latter

principal players in utility restructuring the case of orissa abstract research on reform and restructuring in the electricity supply industry does not adequately focus on the process of actual implementation using the restructuring of orissa state electricity board as a case study this paper identifies the principal players and their roles during the restructuring of an electric utility the key players in a utility restructuring exercise are the government top management lending agencies and the consultants three conceptual phases are identified in the restructuring process namely impetus phase reorganisation phase and consolidation phase as the restructuring process moves from one phase to another the roles of the principal players also undergo significant qualitative changes this paper highlights the changing role of the key players as the restructuring process moves from one phase to another

analysis of the bullwhip effect in a multiproduct setting with interdependent demands the bullwhip effect has been extensively studied primarily based on the analysis of various single product models with a few exceptions we extend the single product analysis to the multiproduct setting of interdependent demand streams with auto correlation and cross product correlation as well as contemporaneous correlation across forecasting errors we find that interdependency between demand streams plays a critical role in determining the existence and magnitude of the bullwhip effect specifically we consider two operating environments a the firm orders product specific materials so that the ordering decision is based on the product level and b the firm orders generic materials so that the order decision is based on the category level we show that even with demand pooling a firm operating at the category level can experience a larger bullwhip effect and a larger order variance under certain conditions that depend on the number of products in the category and the demand dependencies

contagious speculation and a cure for cancer a nonevent that made stock prices soar a sunday new york times article on a potential development of new cancer curing drugs caused entremed s stock price to rise from 12 063 at the friday close to open at 85 and close near 52 on monday it closed above 30 in the three following weeks the enthusiasm spilled over to other biotechnology stocks the potential breakthrough in cancer research already had been reported however in the journal nature and in various popular newspapers including the times more than five months earlier thus enthusiastic public attention induced a permanent rise in share prices even though no genuinely new information had been presented a central tenet of f inancial economics is that an asset should trade at the risk adjusted present value of its expected future cash f lows these expected future cash f lows exist in people s minds and do not normally lend themselves to direct observation an equilibrium price in a frictionless market does not tolerate disagreements among market participants if some people deem the price too low they will buy the asset if others think it is too high they will sell it short if necessary although the efficient markets hypothesis predicts that price changes are unpredictable it associates them with changes in traders beliefs about future cash f lows or the appropriate discount rate beliefs change with the arrival of new information thus in hindsight at least we should be able to ascribe price changes to the arrival of specific new information we examine this view in the context of a series of news reports in the media pertaining to entremed enmd a biotechnology company and other members of its sector the sunday may 3 1998 edition of the new york times reports on a recent breakthrough in cancer research and mentions enmd a company with licensing rights to the breakthrough kolata 1998 the story s impact on the stock prices was immediate huge and to a large extent permanent the new news content of the times story was nil though the substance of the story had been published as a scientific piece in nature boehm et al 1997 and in the popular press including the times itself wade 1997 more than five months earlier in november 1997

revisiting the value of information sharing in two stage supply chains abstract there is a substantive amount of literature showing that demand information sharing can lead to considerable reduction of the bullwhip effect inventory costs the core argument analysis underlying these results is that the downstream supply chain member the retailer quickly adapts its inventory position to an updated end customer demand forecast however in many real life situations retailers adapt slowly rather than quickly to changes in customer demand as they cannot be sure that any change is structural in this paper we show that the adaption speed and underlying unknown demand process crucially affect the value of information sharing for the situation with a single upstream supply chain member manufacturer and a single retailer we consider two demand processes stationary or random walk these represent two extremes where a change in customer demand is never or always structural respectively the retailer and manufacturer both forecast demand using a moving average where the manufacturer bases its forecast on retailer demand without information sharing but on end customer demand with information sharing in line with existing results the value of information turns out to be positive under stationary demand one contribution though is showing that some of the existing papers have overestimated this value by making an unfair comparison our most striking and insightful finding is that the value of information is negative when demand follows a random walk and the retailer is slow to react slow adaptation is the norm in real life situations and deserves more attention in future research exploring when information sharing indeed pays off

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

patterns in stock market movements tested as random number generators this paper shows that tests of random number generators rngs may be used to test the efficient market hypothesis emh it uses the overlapping serial test ost a standard test in rng research to detect anomalous patterns in the distribution of sequences of stock market movements up and down our results show that most stock markets exhibit idiosyncratic recurrent patterns contrary to the efficient market hypothesis also that ost detects a different kind of non randomness to standard econometric long and short memory tests exposure of these anomalies should contribute to making markets more efficient

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

small sample uncertainty aspects in relation to bullwhip effect measurement abstract the bullwhip effect as a concept has been known for almost half a century starting with the forrester effect the bullwhip effect is allegedly observed in many supply chains and it is generally accepted as a potential malice despite this the bullwhip effect still seems to be first and foremost a conceptual phenomenon some even simply denies that the phenomenon exists at all in practice this of course makes it important to perform measurements because only what gets measured gets done as the saying goes in analytics few measurements are reported in the literature however typically based on standard statistical assumptions in the case of a standard measurement of the bullwhip effect independence amongst the participating variables are required amongst others but this is definitely known not to be perfectly true if any systematic control at all have taken place in the supply chain this paper analyses the bullwhip measurement implications in case the standard test assumptions are violated and illustrates how to improve on the testing setup this is further done with a special emphasis on the unavoidable small sample aspects relating to such measurement in practice which typically renders all statistical asymptotic or robust arguments quite unusable it is shown how h 0 95 confidence test intervals still easily can be obtained numerically in such cases

bank run psychology abstract banks are inherently susceptible to panics and bank runs due to the problem of maturity mismatch resulting in both a stable equilibrium in which the bank survives and an unstable equilibrium in which a bank run occurs understanding equilibrium selection in this setting is extremely important for safeguarding financial stability in this paper one new potential factor that determines whether a bank runs gets triggered or not is experimentally studied namely the psychological state of the depositor prior to participating in an experimental bank run game subjects are either induced with fear sadness or happiness using an autobiographical emotion induction task the findings suggest that the presence of background fear significantly increases the likelihood of withdrawal and a subsequent bank run in addition women are shown to be significantly more likely to withdraw then men but only in the fear induction treatment

analysis of a forecasting production inventory system with stationary demand we consider a production stage that produces a single item in a make to stock manner demand for finished goods is stationary in each time period an updated vector of demand forecasts over the forecast horizon becomes available for use in production decisions we model the sequence of forecast update vectors using the martingale model of forecast evolution developed by graves et al 1986 1998 and heath and jackson 1994 the production stage is modeled as a single server discrete time continuous state queue we focus on a modified base stock policy incorporating forecast information and use an approximate analysis rooted in heavy traffic theory and random walk theory to obtain a closed form expression for the forecast corrected base stock level that minimizes the expected steady state inventory holding and backorder costs this expression which is shown to be accurate under certain conditions in a simulation study sheds some light on the interrelationships among safety stock stochastic correlated demand inaccurate forecasts and random and capacitated production in forecasting production inventory systems

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

good day sunshine stock returns and the weather psychological evidence and casual intuition predict that sunny weather is associated with upbeat mood this paper examines the relationship between morning sunshine in the city of a country s leading stock exchange and daily market index returns across 26 countries from 1982 to 1997 sunshine is strongly significantly correlated with stock returns after controlling for sunshine rain and snow are unrelated to returns substantial use of weather based strategies was optimal for a trader with very low transactions costs however because these strategies involve frequent trades fairly modest costs eliminate the gains these findings are difficult to reconcile with fully rational price setting

order variability in perishable product supply chains abstract empirical research has shown that the degree of order variability in supply chains is significantly influenced by product and industry specific factors this paper analyzes the impact of perishability on order variability and the bullwhip effect in supply chains we decompose the ordering process of a retailer into a sales and an outdating process and quantify their short and long term variability and correlation we find differences to non perishable product supply chains driven by the impact of the inventory depletion policy stock out management and retailers service level requirement these three factors significantly affect the retailer s order variability and thus the decision making process and the profitability of the upstream supply stage for the majority of instances the perishable nature of a product results in the ordering process having a lower variability than the demand process only when inventory depletion is dominated by last in first out in high service level environments variability amplification can be observed we propose a dynamic ordering policy for the upstream supply stage taking into account negative correlation of retailer orders between periods this dynamic policy may lead to substantial performance improvements in a sensitivity analysis we investigate the impact of shelf life lead time and demand correlation

the bullwhip effect progress trends and directions the bullwhip effect refers to the phenomenon where order variability increases as the orders move upstream in the supply chain this paper provides a review of the bullwhip literature which adopts empirical experimental and analytical methodologies early econometric evidence of bullwhip is highlighted findings from empirical and experimental research are compared with analytical and simulation results assumptions and approximations for modelling the bullwhip effect in terms of demand forecast delay replenishment policy and coordination strategy are considered we identify recent research trends and future research directions concerned with supply chain structure product type price competition and sustainability

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

poker player behavior after big wins and big losses we find that experienced poker players typically change their style of play after winning or losing a big pot most notably playing less cautiously after a big loss evidently hoping for lucky cards that will erase their loss this finding is consistent with kahneman and tversky s kahneman d a tversky 1979 prospect theory an analysis of decision under risk econometrica47 2 263 292 break even hypothesis and suggests that when investors incur a large loss it might be time to take a vacation or be monitored closely

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

information transmission and the bullwhip effect an empirical investigation the bullwhip effect is the amplification of demand variability along a supply chain a company bullwhips if it purchases from suppliers more variably than it sells to customers such bullwhips amplifications of demand variability can lead to mismatches between demand and production and hence to lower supply chain efficiency we investigate the bullwhip effect in a sample of 4 689 public u s companies over 1974 2008 overall about two thirds of firms bullwhip the sample s mean and median bullwhips both significantly positive respectively measure 15 8 and 6 7 of total demand variability put another way the mean quarterly standard deviation of upstream orders exceeds that of demand by 20 million we decompose the bullwhip by information transmission lead time estimating the bullwhip s information lead time components with a two stage estimator we find that demand signals firms observe with more than three quarters notice drive 30 of the bullwhip and those firms observe with less than one quarter s notice drive 51 from 1974 1994 to 1995 2008 our sample s mean bullwhip dropped by a third this paper was accepted by christian terwiesch operations management

rain emotions and voting for the status quo abstract do emotions affect the decision between change and the status quo we exploit exogenous variation in emotions caused by rain and analyze data on more than 870 000 municipal vote outcomes in switzerland to address this question the empirical tests are based on administrative ballot outcomes and individual postvote survey data we find that rain decreases the share of votes for political change our robustness checks suggest that this finding is not driven by changes in the composition of the electorate and changes in information acquisition in addition we provide evidence that rain might have altered the outcome of several high stake votes we discuss the psychological mechanism and document that rain reduces the willingness to take risks a pattern that is consistent with the observed reduction in the support for change

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

the multivariate bullwhip effect abstract a multivariate bullwhip expression for m products with an order up to inventory policy is developed the demand models under consideration are differenced stationary vector time series with a wold representation for which general forecasting formulas are available resulting in a large class of possible models including nonstationary ones examples are provided for common demand models and implemented on sales data it is found that the multivariate approach gives rise to mechanisms for understanding and reducing the bullwhip effect through horizontal information sharing particularly for the nonstationary demand case in the stationary setting a more nuanced approach to bullwhip reduction can be achieved by managing the relationship between cross correlations and lead times a method of determining whether a multivariate or univariate approach generates a lower bullwhip effect is proposed

the sampling error in estimates of mean variance efficient portfolio weights this paper presents an exact finite sample statistical procedure for testing hypotheses about the weights of mean variance efficient portfolios the estimation and inference procedures on efficient portfolio weights are performed in the same way as for the coefficients in an ols regression ols t and f statistics can be used for tests on efficient weights and when returns are multivariate normal these statistics have exact t and f distributions in a finite sample using 20 years of data on 11 country stock indexes we find that the sampling error in estimates of the weights of a global efficient portfolio is large

exploitable predictable irrationality the fifa world cup effect on the u s stock market in a recently published paper edmans garcia and norli 2007 reveal a strong association between results of soccer games and local stock returns inspired by their work we propose a novel approach to exploit this effect on the aggregate international level with the following three unique features i the aggregate effect does not depend on the games results hence the effect is an exploitable predictable effect ii the aggregate effect is based on many games hence it is very large and highly significant we find that the average return on the u s market over the world cup s effect period is 2 58 compared to 1 21 for all days average returns over the same period length iii exploiting the aggregate effect is involved with trading in a single index for a relatively long period

quantifying the bullwhip effect using two echelon data a cross industry empirical investigation the bullwhip effect denotes the phenomenon whereby demand variability is amplified from a downstream site buyer to an upstream site supplier in the supply chain this paper contributes to the literature that empirically investigates the bullwhip effect by providing new evidence regarding its prevalence and magnitude in contrast to previous work we use a two echelon approach which allows us to observe variations at both the upstream and the downstream sites by drawing on a financial accounting standard regarding information disclosure about major customers we are able to link 5494 buyers and suppliers in the u s between 1976 and 2009 we merge this information with quarterly financial accounting data to form a sample of 14 933 buyer supplier dyad observations we correct for sample selection bias using propensity score matching and estimate the average bullwhip effect in our sample to be 1 90 i e 90 demand variability amplification between echelons a significant bullwhip effect is observed across industries mining manufacturing wholesale and retail and is supported by several robustness checks we investigate and discuss how these results can be generalized beyond our sample

stock return comovement around the dow jones islamic market world index revisions we examine patterns of comovement in stock returns around the dow jones islamic market world index djimwi quarterly revision events our analysis is based on a sample of 8250 companies from eighteen countries during the period may 1999 june 2012 we find that a stock s comovement with the djimwi increases when it joins and decreases when it leaves the index we also find that the comovement of newly added deleted stocks with the existing djimwi constituents increases declines during periods of high trading activity and during the month of ramadan further tests reveal that changes in the fundamentals have no impact on the comovements of added and deleted stocks overall our results indicate that stock returns respond to the emotional state of investors around information free events

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

a two echelon allocation model and the value of information under correlated forecasts and demands abstract in this article we explore the effects of incorporating forecasts explicitly in a two echelon allocation model which consists of a central depot and several retailers in particular we investigate the possible benefits on the system costs and inventory levels the depot does not hold any inventory and the demand is observed only at the retailers under a general correlated demand forecast structure we obtain the approximate system wide order up to level and the expected system cost in order to assess the value of information provided by keeping track of the forecasts we construct a comparable inventory system operating under a standard demand model we demonstrate that the standard demand model results in higher order up to levels and higher system costs

mood fluctuations projection bias and volatility of equity prices this paper focuses on the potential e2ects of small uctuations in investors subjective preferences speci5cally their discount factors and attitudes towards risk on the volatility of equity prices we brie y summarize some of the arguments and evidence regarding the uctuations in subjective preferences our analysis indicates that such uctuations may have signi5cant implications for understanding the volatility of the prices of 5nancial assets we derive a closed form expression for equilibrium equity prices and use this expression to map the uctuations in investors subjective preferences to the uctuations in equity prices our analysis suggests that small uctuations in the discount factor have potentially large e2ects on the latter for example if the standard deviation of the uctuations in the discount factor is of the order of 1 10th of one percent then this by itself can induce a 3 4 standard deviation in the uctuations in equity prices the uctuations in the attitude towards risk have a smaller but nevertheless non negligible e2ect we present the intuition underlying our conclusions c 2002 published by elsevier science b v

here comes the rain again weather and the intertemporal substitution of leisure i revisit the intertemporal labor supply framework using exogenous variations in daily weather to see how time at work varies with rain in my model a rainy day is associated with a lower enjoyment of leisure effectively increasing wages and bringing more hours at work i test the model using data from the american time use survey supplemented with daily weather i find that on rainy days men shift on average 30 minutes from leisure to work computations give a rough estimate of the intertemporal elasticity of labor supply of around 0 01 in line with the rest of the literature

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

bayesian herders updating of rainfall beliefs in response to external forecasts summary temporal climate risk weighs heavily on many of the world s poor model based climate forecasts could benefit such populations provided recipients use forecast information to update climate expectations we test whether pastoralists in southern ethiopia and northern kenya update their expectations in response to forecast information the minority of herders who received these climate forecasts updated their expectations for below normal rainfall but not for above normal rainfall this revealed preoccupation with downside risk highlights the potential value of better climate forecasts in averting drought related losses but realizing any welfare gains requires that recipients strategically react to these updated expectations

power sector reform in orissa an ex post analysis of the causal factors abstract from the early 1990s dramatic changes have been taking place in the structure of electricity supply industry esi worldwide the primary reasons for electricity sector reform has however been different for industrialised and developing countries the objective of this paper is to study and identify various factors leading to power sector reform in developing countries the restructuring of orissa state electricity board in india was used as a case study in identifying the various factors the factors that result in implementation of restructuring are a contextual factors they are the primary drivers for initiating reform the performance of the utility and the conditionalities of the lending agencies are contextual factors b trigger factor it is the determining factor that creates a compelling necessity to undergo restructuring the inability of the government to continue to support the utility acts as the trigger factor c facilitating factors they act as facilitators for initiating reform support of the government absence of a powerful lobby and the support of the top management are facilitating factors

losing sleep at the market the daylight saving anomaly reply motivated by the recent flurry of activity in sleep research this paper explores the connection between sleep disruptions following spring and fall clock shifts associated with daylight savings time and equity returns it is shown that the weekend effect in the form of the lower than expected friday to monday returns is particularly pronounced for the two weekends involving daylight savings clock changes this abstract was borrowed from another version of this item