conditions that cause risk pooling to increase inventory abstract we say product a is a partial substitute for product b if a fraction of the customers who prefer b are willing to accept a when b is out of stock when demand is uncertain it is intuitive and true that a larger willing to substitute fraction implies larger expected profits a higher willing to substitute fraction allows one to pool the risk of individual products it may also be intuitive that a larger willing to substitute fraction might result in lower optimal total inventory for the full substitution structure several researchers have shown that for certain distributions such as the exponential this latter intuition is not true we show that this full substitution anomaly can occur with any right skewed demand distribution we assume i i d demand distributions unless we indicate otherwise we also show that the anomaly can occur for a number of realistic situations of partial substitution with commonly used demand distributions such as normal exponential poisson and uniform we also demonstrate the anomaly for more than one period with backlogging lost sales more than two products and with setup costs

multiattribute preference analysis with performance targets this paper develops an approach based on performance targets to assess a preference function for a multiobjective decision under uncertainty this approach yields preference functions that are strategically equivalent to conventional multiattribute utility functions but the target oriented approach is more natural for some classes of decisions in some situations the target oriented preference conditions are analogous to reliability theory conditions for series or parallel failure modes in a system in such cases reinterpreting the conditions using reliability concepts can be useful in assessing the preference function the target oriented approach is also a generalization of common forms of goal programming the approach has particular applicability for resource allocation decisions where the outcome of the decision is significantly determined by the actions of other stakeholders to the decision such as new product development or decision making in a controversial regulated environment

forecasting foreign exchange rates with an intrinsically nonlinear dynamic speed of adjustment model forecasting foreign exchange rates is an important but difficult process therefore it is important to use a superior forecasting model the paper takes up this criterion and proposes to describe and forecast foreign exchange rates by developing an intrinsically nonlinear model with variable and dynamic speeds of adjustment it is found that the speed of adjusting the random or expected to the equilibrium rate is very slow implying that fiscal policy statistically insignificat and monetary policy statistically significant may be ineffective to induce changes in the adjustment speed we also find that the nonlinear dynamic model improves forecasting performance implying that nonlinearities in the sense of functional forms are exploitable for improved point forecasting of foreign exchange rates

estimation of consumer demand with stock out based substitution an application to vending machine products the occurrence of temporary stock outs at retail is common in frequently purchased product categories available empirical evidence suggests that when faced with stock outs consumers are often willing to buy substitute items an important implication of this consumer behavior is that observed sales of an item no longer provide a good measure of its core demand rate sales of items that stock out are right censored while sales of other items are inflated because of substitutions knowledge of the true demand rates and substitution rates is important for the retailer for a variety of category management decisions such as the ideal assortment to carry how much to stock of each item and how often to replenish the stock the estimated substitution rates can also be used to infer patterns of competition between items in the category in this paper we propose methods to estimate demand rates and substitution rates in such contexts we develop a model of customer arrivals and choice between goods that explicitly allows for possible product substitution and lost sales when a customer faces a stock out the model is developed in the context of retail vending an industry that accounts for a sizable part of the retail sales of many consumer products we consider the information set available from two kinds of inventory tracking systems in the best case scenario of a perpetual inventory system in which times of stock out occurrence and cumulative sales of all goods up to these times are observed we derive maximum likelihood estimates mles of the demand parameters and show that they are especially simple and intuitive however state of the art inventory systems in retail vend ing provide only periodic data i e data in which times of stock out occurrence are unobserved or missing for these data we show how the expectation maximization em algorithm can be employed to obtain the mles of the demand parameters by treating the stock out times as missing data we show an application of the model to daily sales and stocking data pooled across multiple beverage vending machines in a midwestern u s city the vending machines in the application carry identical assortments of six brands since the number of parameters to be estimated is too large given the available data we discuss possible restrictions of the consumer choice model to accomplish the estimation our results indicate that demand rates estimated naively by using observed sales rates are biased even for items that have very few occurrences of stock outs we also find significant differences among the substitution rates of the six brands the methods proposed in our paper can be modified to apply to many nonvending retail settings in which consumer choices are observed not their preferences and choices are constrained because of unavailability of items in the choice set one such context is in store grocery retailing where similar issues of information availability arise in this context an important issue that would need to be dealt with is changes in the retail environment caused by retail promotions

single period multiproduct inventory models with substitution we study a single period multiproduct inventory problem with substitution and proportional costs and revenues we consider n products and n demand classes with full downward substitution i e excess demand for class i can be satisfied using product j for i j we first discuss a two stage profit maximization formulation for the multiproduct substitution problem we show that a greedy allocation policy is optimal we use this to write the expected profits and its first partials explicitly this in turn enables us to prove additional properties of the profit function and several interesting properties of the optimal solution in a limited computational study using two products we illustrate the benefits of solving for the optimal quantities when substitution is considered at the ordering stage over similar computations without considering substitution while ordering specifically we show that the benefits are higher with high demand variability low substitution cost low profit margins or low price to cost ratio high salvage values and similarity of products in terms of prices and costs

inventory competition for newsvendors under the objective of profit satisficing abstract inventory competition for newsvendors nvs has been studied extensively under the objective of expected profit maximization which is based on risk neutrality in this paper we study this classic problem under the objective of profit satisficing which is based on downside risk aversion consistent with prior literature we consider two possible scenarios in the first scenario each nv s demand depends on the stocking levels of all nvs other than herself in this scenario we show that there is a unique nash equilibrium where all nvs optimally order as if they were independent in the second scenario each nv s demand depends on the stocking levels of all nvs including herself we prove the existence of nash equilibrium for both additive and multiplicative forms of demands as a special case we also study symmetrical nvs under the proportional allocation model we show that at equilibrium if the number of nvs exceeds a threshold the market becomes highly competitive

a reexamination of purchasing power parity a multicountry and multiperiod study abstract this paper re examines the purchasing power parity ppp theory in a multiple exchange rate world owing to a lack of precision in estimating the parameters many authors concluded that ppp did not hold very well in the 1970s using a time series cross sectional estimation procedure we are unable to reject the hypothesis that ppp holds in several currencies simultaneously in addition the parameters are precisely estimated this result follows from the estimation procedure which allows us to exploit the cross sectional variation in the data and the contemporaneous correlation in the deviations from ppp

how to set price and quality in a supply chain of virtual products under bi criteria and risk consideration abstract virtual products are characterized by ample production capacity zero lead time and no holding costs we consider a two echelon supply chain of a virtual product consisting of a single manufacturer and a single retailer who face random demand demand depends on both price and quality of the product and its stochastic nature exposes the supply chain members to financial risk each party adopts profit criteria that reflect his or her attitude toward this risk including the use of bi criteria by formulating a model that follows a stackelberg game and using the stochastic dominance property we show that one can analytically obtain equilibrium by assuming certain common structures of the demand function and of the risk attitudes the contribution of this study is fourfold i analyzing multiplicative and additive demand forms and comparing the properties of the decisions under the two forms ii showing that under the multiplicative demand form the pricing strategies are not affected by the parties attitudes toward risk whereas the manufacturer s decision on quality investment is affected by his risk attitude iii showing that under the additive demand form the manufacturer s utility function and the demand uncertainty affect pricing and investment strategies and iv suggesting a method to construct the efficient set of decisions and the non dominated set of profit criterion values

exchange rates and news reply abstract in this reply i arge that the results of my 1982 article in this journal are not affected either at a theoretical or empirical level by longworth s 1984 comments however i also argue that longworth s proposition of including variables pertaining to other countries in empirical market efficiency studies should be investigated further

impact of loss aversion on the newsvendor game with product substitution abstract this paper studies a newsvendor game in which two substitutable products are sold by two different retailers newsvendors with loss averse preferences each loss averse retailer facing stochastic customer demand and deterministic substitution rate will make an order quantity decision to maximize his expected utility since product substitution causes two retailers to make decisions in a competitive environment game theory is used to find the retailers optimal order quantities it is shown that under certain conditions there exists a unique nash equilibrium in the newsvendor game under a symmetry assumption each retailer s equilibrium order quantity is decreasing in the loss aversion coefficient and increasing in the substitution rate further if the effect of loss aversion on the order quantity is strong enough to dominate the effect of competition the total inventory level of a decentralized supply chain will be lower than that of a centralized supply chain numerical experiments are conducted to illustrate our results

the speculative efficiency hypothesis the hypothesis that forward prices are the best unbiased forecast of future spot prices is often presented in the economic and financial analysis of futures markets this paper considers the hypothesis independently of its implications for rational expectations or market efficiency and in order to stress this fact the term speculative efficiency is used to characterize the state envisaged under the hypothesis if a market is subject to efficient speculation the supply of speculative funds is infinitely elastic at the forward price that is equal to the expected future spot price the expected future spot price is a market price determined as the solution to the underlying rational expectations macroeconomic model although the paper is primarily concerned with testing this hypothesis in the foreign exchange market the methodology introduced in the paper is of general application to all futures markets this abstract was borrowed from another version of this item

economic news exchange rates and interest rates the paper esamines the post october 1979 response of exchange rates and interest rates to the new information contained in the first announcement of fifteen us macroeconomic series illarkets respond primarily to monetary news but also to news about the trade deficit domestic inflation and variables that reflect the state of the business cycle for all fifteen macroeconomic variables an increase decrease in interest rates is accompanied by an appreciation depreciation of the dollar which is consistent with models that stress price rigidity and absence of purchasing power parity the effect of economic news on asset prices has received increasing attention in the economic literature because an outcome of the efficient markets rational expectations hypothesis is that flesible asset prices change the moment new information about future fundamentals arrives in the market in the exchange rate literature the role of news has gained importance because structural models have failed to predict most of the variation in exchange rates during the 1970s see imeese and rogoff 1983 researchers were naturally led to investigate the types of news that make exchange rates so volatile and to utilize news in order to test which model of exchange rate determination is consistent with the floating eschange rate experience notable studies are those of dornbusch 1980 frenkel 1981 edwards 1982a b 1983 copeland 1984 and rose 1984 in this paper i also examine the effects of macroeconomic news on eschange rates but i adopt a different more direct strategy one that complements previous work avoids some of its shortcomings and promises interesting conclusions i examine the instantaneous response of exchange rates the moment a piece of economic news hits the market if one can isolate the exact time during a business day when news arrives it is straightforward to examine the response of exchange rates because financial data are continuously available the advantages of the present methodology are many first it is possible to identify the exact types of economic news and how they affect exchange rates second the simultaneity bias which plagues the previous literature on exchange rates and news is not present here the independent variables that represent news can be interpreted as causal the paper was presented at the 1985 meeting ofthe american economic association the author wishes to thank sebastian edwards r w hafer nicholas karamouzis andrew rose and two anonymous referees for helpful comments kim rupert of the money market services for providing the survey data soo kounne for able research assistance and barnard college for research support

analysis of protection and pricing strategies for digital products under uncertain demand abstract we analyze pricing and protection digital rights management strategies in a two echelon supply chain that consists of a manufacturer and a retailer of digital products the demand for the legal non pirated product which depends on both price and monetary investment in protection is assumed to be uncertain three different supply chain models are analyzed manufacturer stackelberg retailer stackelberg and vertical integration we show that the retailer s utility function has no effect on the equilibrium strategies and suggest schemes to find these strategies for any utility function of the manufacturer further results are obtained under assumptions of either a multiplicative or an additive demand model we study the players strategies under different profit criteria reflecting different attitudes toward risk specifically the expectation criterion and the target criterion and for each criterion we obtain the dependence between the pricing and the protection investment we show that there are situations in which the manufacturer can increase his profit by giving up his leadership to the retailer even if the power balance is in his favor

the influence of fundamentals on exchange rates findings from analyses of news effects as we survey the literature of macroeconomic news in the foreign exchange market we can by now look back on nearly 30 years of research the first studies which analysed news effects on exchange rates were established in the early 1990s see for example dornbusch almost at the same time meese and rogoff published their influential paper revealing the forecasting inferiority in exchange rates of structural models against the random walk this finding has shocked the pillars of exchange rate economics and thus cast general suspicion on research focusing on fundamentals in this field the eventual rising popularity of event studies can partly be attributed to the re establishment of the raison d etre of exchange rate economics this work focuses on systematically surveying this literature with particular respect to its primary goal i e shedding light on the analytical value of fundamental research thus its major findings are first fundamental news does matter whereas non fundamental news matters to a lesser degree second news influences exchange rates via two separated channels i e incorporating common information into prices directly or indirectly based upon order flow third with a few exceptions the impact of fundamental news on exchange rates is fairly stable over time

the collapse of purchasing power parities during the 1970 s one of the striking facts concerning the relationship beiveen prices and exchange rates during the 1970 s has been the dismal performance of the predictions of the simple versions of the purchasing power parity doctrine ppp that doctrine in its absolute version states that the equilibrium exchange rate between domestic and foreign currencies equals the ratio of domestic to foreign price levels the relative version of the doctrine relates equilibrium changes in exchange rates to changes in the ratio of domestic to foreign prices during the 1970 s short run changes in exchange rates bore little relationship to short run differentials in national inflation rates and frequently divergences from purchasing power parities have been cumulative this paper reviews and analyzes the empirical record of exchange rates and prices during the 1970 s and the analysis is based on the experience of the dollar pound the dollar frecch franc and the dollar dm exchange rates section 2 presents the evidence on ppp during the 1970 s and contrasts it with the evidence from the 1920 s a period during which the doctrine held up reasonably well this analysis is relevant for assessing whether the flexible exchange rate system was successful in providing national economies with an added degree of insulation from foreign shocks and whether it provided policymakers with an added instrument for the conduct of macroeconomic policy the evidence regarding devia tions from purchasing power parities is also relevant for determining whether there is a case for managed float section 3 attempts to explain what went wrong with

a single period inventory placement problem for a supply system with the satisficing objective abstract consider the inventory placement problem in an n stage supply system facing a stochastic demand for a single planning period each stage is a stocking point holding some form of inventory e g raw materials subassemblies product returns or finished products that after a suitable transformation can satisfy demand stocking decisions are made before demand occurs unsatisfied demands are lost the revenue salvage value ordering transformation and lost sales costs are proportional there are fixed costs for utilizing stages for stock storage the objective is to maximize the probability of achieving a given target profit level we prove the existence of optimal stocking decisions where at most three stages receive nonzero stocks we also characterize properties of the optimal stocking decisions and provide an o n 3 algorithm for their computation for the special case where all fixed costs are zero the stages utilized do not depend on the demand distribution or the target level and one can find optimal stocking decisions by performing a simple o n 2 search and solving a single variable optimization problem

analytical and managerial implications of integrating product substitutability in the joint pricing and procurement problem abstract this paper studies the analytical and managerial implications of product substitutability on the joint pricing and procurement decisions we consider a single period model with two products an existing product and an improved new product that can substitute the demand for the existing product in case of a shortage demand for each product follows a general distribution with an expected value that is a linear function of the price of the new product while the price of the existing product is determined by the market it is necessary to determine the new product s price and the procurement quantities of both products so as to maximize the profits we analytically show that the expected profit function is unimodal and in the existence of substitution the expected total profit is higher the optimal price and the safety stock of the new product are higher and the optimal safety stock of the existing product is less using these properties an efficient algorithm is developed we also provide a numerical analysis to demonstrate that considering substitution in advance could increase the profitability by 58 and the new product price by 5 while decreasing the total procurement quantity by 15

optimal advertising and pricing for new green products in the circular economy abstract in the circular economy era environmental sustainability is critical and both green and non green products with similar functions co exist in practice there is little doubt that these two types of products are competing and may substitute one another even though one is more environmental friendly than the other in this paper we build analytical models to explore the optimal advertising and pricing decisions for a green product in the presence of a non green product substitute we investigate both simultaneous and sequential pricing strategies under which there are three possible pricing scenarios namely 1 both prices of green and non green products are determined simultaneously strategy ip 2 the green product s price is decided first and then the non green product s price is determined strategy gl and 3 the non green product s price is decided first and then the green product s price is determined strategy nl we find that the sequential pricing strategy is more profitable than the simultaneous pricing strategy for both green and non green supply chains it is interesting to prove the existence of second mover advantage in the pricing game moreover we identify that if the green supply chain uses strategy nl it could achieve a better performance in profit and minimize the corresponding environmental impact if the green supply chain is truly socially responsible it should design a product with low substitutability so that the environmental impact can be enhanced furthermore our numerical results indicate that strategy ip never performs the best in terms of consumer surplus and social welfare when the product substitution level is sufficiently high findings of this paper contribute to the literature on cleaner production systems in the circular economy era

demand uncertainty and sales a study of fashion and markdown pricing the theory of clearance sales is expanded and applied to explain why markups markdowns and the frequency of sales of merchandise sold by department stores have increased dramatically in recent years and why they differ across merchandise groups tha major theme of the paper is that the growing role of fashion and product variety is an important reason for these increases and for the differences between merchandise groups the growing importance of fashion is illustrated by documenting the declining use of whites and the increasing use of colors and prints estimates of the effects of imports and technological and demographic changes on markups and markdowns are presented copyright 1988 by american economic association

newsvendor solutions via conditional value at risk minimization abstract in this paper we consider the minimization of the conditional value at risk cvar a most preferable risk measure in financial risk management in the context of the well known single period newsvendor problem which is originally formulated as the maximization of the expected profit or the minimization of the expected cost we show that downside risk measures including the cvar are tractable in the problem due to their convexity and consequently under mild assumptions on the probability distribution of products demand we provide analytical solutions or linear programming lp formulation of the minimization of the cvar measures defined with two different loss functions numerical examples are also exhibited clarifying the difference among the models analyzed in this paper and demonstrating the efficiency of the lp solutions

exchange rates and news a multi currency approach abstract in this paper a multi currency model is used to investigate the relationship between spot exchange rates forward rates market efficiency and new information it is shown that in a world with more than two countries the error term in the standard market efficiency tests will be correlated across rates it is also shown that the exchange rate can be expressed as a function of factors known in advance which are captured by the forward rate determined in the previous period and news the empirical results presented in the paper tend to support the model s implications

value at risk and inventory control the purposes of this paper are two fold on the one hand we shall provide a decision analysis justification for the value at risk var approach based on ex post disappointment decision making arguments we shall show that the var approach is justified by a disappointment criterion in other words the asymmetric valuation between ex ante expected returns above an appropriate target return and the expected returns below that same target level provide an explanation for the var criterion when it is used as a tool for var efficiency design second this paper provides applications to inventory management based on var risk exposure although the mathematical problems arising from an application of the var approach tuned to current practice in financial risk management are difficult to solve analytically solutions can be found by application of standard computational and simulation techniques a number of cases are solved and formulated to demonstrate the paper s applicability

the risk averse and prudent newsboy the effects of risk and risk aversion in the single period inventory newsboy problem are examined comparative static effects of changes in the various price and cost parameters are determined and related to the newsboy s risk aversion the addition of a random background wealth and of an increase in the riskiness of newspaper demand are also examined although many of the comparative effects generally are ambiguous some fairly simple restrictions on preferences and or risk increases are shown to lead to qualitatively deterministic results

price competition for retailers with profit and revenue targets abstract price competition for retailers has been extensively studied in the literature assuming the objective of expected profit maximization in this paper we make a major contribution by studying price competition for retailers with both profit and revenue targets consequently each retailer maximizes her profit and revenue probability namely the probability of achieving the profit and revenue targets simultaneously more specifically we analyze a scenario where two competing retailers purchase a perishable product from a common supplier and sell to a common market employing the isoelastic demand model we derive the closed form solutions of the optimal order quantity the optimal selling price and the maximal profit and revenue probability for each retailer it is shown that when revenue is a relevant performance measure positive and non positive salvage values lead to different optima for competing retailers moreover as price elasticity and or price competition intensity becomes higher the optimal retail price decreases and the optimal order quantity increases for each retailer

a note on the determinants of unexpected exchange rate movements abstract in this paper we study the relative importance of surprises in fundamentals in explaining unexpected exchange rate movements employing a unique survey dataset that contains matched exchange rate and interest rate expectations we are able to derive a number of interesting conclusions a variance decomposition of unexpected exchange rate movements into various components reveals that interest rate news is relatively unimportant but that changes in perceptions about risk premia and more importantly revisions of expectations with regard to future exchange rate levels are crucial in explaining unexpected exchange rate movements

note note on optimal ordering quantity to realize a pre determined level of profit in this note we consider the one period inventory model in which it is required to determine the order quantity which maximizes the probability of realizing a predetermined level of profit r we give a condition for determining the optimal order quantity and provide explicit expressions for the optimal order quantity in three special cases

an integrated assortment and shelf space optimization model with demand substitution and space elasticity effects abstract retailers must define their assortments and assign shelf space to the items included in these assortments these two planning problems are mutually dependent if space is scarce we formulate a model that maximizes a retailer s profit by selecting the optimal assortment and assigning limited shelf space to items this model is the first decision model to integrate assortment and shelf space planning by considering stochastic and space elastic demand out of assortment and out of stock substitution effects to solve the model we develop a specialized heuristic that efficiently yields near optimal results even for large scale problems we show that our approach outperforms alternative approaches e g a sequential planning approach that first picks assortments and then assigns shelf space by up to 18 and a greedy algorithm by up to 16 in terms of profit we test our model on two real data sets for perishable and non perishable items and show how it can support retailers in increasing their profits by up to 25 we then use the model to generalize these results and find that space elasticity and substitution effects have a significant impact on profits assortment size as well as facing decisions and that both effects reinforce each other using our model we finally derive rules of thumb for planners in practice

the multi product price setting newsvendor with resource capacity constraints abstract in this paper we consider a newsvendor problem commonly encountered in retail stores that cater to budget sensitive shoppers the newsvendor sells multiple products and in addition to determining order quantities must also determine the selling price of each product sold the demand for each product is of a stochastic nature and depends on the demands of other products i e is cross elastic we transform the objective function into a form that is amenable to developing integer programming solutions and then develop a numeric optimization procedure rooted in the nelder mead search technique we obtain encouraging numerical results on some small scale and large scale problems to the best of our knowledge this is the first work that produces implementable solutions for a scenario that is particularly relevant to retailers catering to budget sensitive customers who are abundant in the current economy

coordination and profit sharing between a manufacturer and a buyer with target profit under credit option several studies have focused on buyer vendor coordination through quantity discount credit option mechanism but few quantitative models and investigations are available that have explored the mechanism for transfer of surplus generated due to coordination in this paper we develop a coordination mechanism through credit option such that both the parties can divide the surplus equitably after satisfying their own profit targets two situations are explored here in the first situation both the parties have no individual profit target from the business whereas in the second situation there are individual profit target for both the parties the proposed mechanism for division of surplus is studied through a numerical study and the impact of different parameter values on the results are examined

a model of speculative efficiency with news error components this paper proposes a theoritical model to assess of news on the spot forward exchange rate relationship and thereby predicts of the impact of news on the exchange rate two types of news are analysed rational expectations type innovations and announcement effects form newspapers by using historical data form a time period which includes the german hyperinflation of the early 1920s an estimate from of the model is derived which is substantially simpler than the version requried using contemporary data preliminary results support the main theoretical predictions but also cast some doubt on a literal interpretation of the exchange rate model plus rational expectations

incentive and production decisions for remanufacturing operations we consider a manufacturer producing original products using virgin materials and remanufactured products using returns from the market where the amount of returns depend on the incentive offered by the manufacturer we determine the optimal value of this incentive and the optimal production quantities in a stochastic demand setting with partial substitution we analyze 3 different models in centralized and decentralized settings where the collection process of the returns is managed by a collection agency in the decentralized setting we also analyze contracts to coordinate the decentralized systems and determine the optimal contract parameters finally we present our computational study to observe the effect of different parameters on the system performance

risk aversion in inventory management traditional inventory models focus on risk neutral decision makers i e characterizing replenishment strategies that maximize expected total profit or equivalently minimize expected total cost over a planning horizon in this paper we propose a framework for incorporating risk aversion in multiperiod inventory models as well as multiperiod models that coordinate inventory and pricing strategies we show that the structure of the optimal policy for a decision maker with exponential utility functions is almost identical to the structure of the optimal risk neutral inventory and pricing policies these structural results are extended to models in which the decision maker has access to a partially complete financial market and can hedge its operational risk through trading financial securities computational results demonstrate that the optimal policy is relatively insensitive to small changes in the decision maker s level of risk aversion

optimal ordering quantities for multi products with stochastic demand return cvar model abstract multi product ordering problem with stochastic demand is often optimized by the expected cost reduction or the expected profit improvement in most of previous works moreover risk preference of decision maker is often ignored evidently this approach is impracticable when the corresponding volatility is larger based on the outstanding characteristics of conditional value at risk cvar as a risk measure the paper proposes an optimal order model for multi product with cvar constraints also the model is finally formulated as a linear programming problem the model is simulated for the case of a newsvendor to analyze to what degree it succeeds the solution in fact is bound consistent fully with the decision maker s intuition on return risk decision making finally results of return cvar model and the classical model are compared and shows that return cvar model is more flexible than the classical model

an efficient algorithm for capacitated assortment planning with stochastic demand and substitution abstract the ever increasing product variety in grocery retailing is in conflict with the limited shelf space managing the assortment and regular order quantity for perishable and non perishable products is therefore a core task for retailers retailers want to maximize profit by considering potential revenues purchase costs diminishing profits for products and opportunity costs for unfulfilled demand when determining assortment sizes and order volume to meet stochastic consumer demand we considered a newsvendor based decision model that jointly optimizes assortment size and the associated order volumes for listed items the model considers out of assortment ooa and out of stock oos substitution effects the model is a structural equivalent to the model described in kok and fisher 2007 and solved there via a heuristic procedure we develop an optimal solution procedure and a time efficient heuristic that solves the model the heuristic suggested is applicable for practically relevant large scale problem instances numerical tests reveal that the heuristic procedure produces close to optimal solutions and outperforms the kok and fisher heuristic with regard to both computational time and solution quality a simulation study with discrete demand justifies our approach with using continuous demand distributions the numerical analyses show that considering substitution effects in a decision based model has a significant impact on the total profit and solution structure further managerial insights are presented with regard to assortment heterogeneity when shelf size substitution and demand variability are varied

exchange rate market efficiency and new information abstract this paper uses a multi currency approach to analyze the relationship between forward exchange rates future spot rates and new information the empirical results tend to support the hypothesis that the exchange rate can be expressed as a function of factors known in advance and news

stocking retail assortments under dynamic consumer substitution we analyze a single period stochastic inventory model newsboy like model in which a sequence of heterogeneous customers dynamically substitute among product variants within a retail assortment when inventory is depleted the customer choice decisions are based on a natural and classical utility maximization criterion faced with such substitution behavior the retailer must choose initial inventory levels for the assortment to maximize expected profits using a sample path analysis we analyze structural properties of the expected profit function we show that under very general assumptions on the demand process total sales of each product are concave in their own inventory levels and possess the so calleddecreasing differences property meaning that the marginal value of an additional unit of the given product is decreasing in the inventory levels of all other products for a continuous relaxation of the problem we then show via counterexamples that the expected profit function is in general not even quasiconcave thus global optimization may be difficult however we propose and analyze a stochastic gradient algorithm for the problem and prove that it converges to a stationary point of the expected profit function under mild conditions finally we apply the algorithm to a set of numerical examples and compare the resulting inventory decisions to those of some simpler naive heuristics the examples show that substitution effects can have a significant impact on an assortment s gross profits the examples also illustrate some systematic distortions in inventory decisions if substitution effects are ignored in particular under substitution one should stock relatively more of popular variants and relatively less of unpopular variants than a traditional newsboy analysis indicates

the multi item newsvendor model with cross selling and the solution when demand is jointly normally distributed abstract products are often demanded in tandem because of the cross selling effect the demand for an item can increase if sales of its cross selling associated items are achieved or decrease when the associated items are out of stock resulting in lost sales therefore a joint inventory policy should be pursued in a cross selling system this paper introduces customer driven cross selling into centralized and competitive newsvendor nv models by representing an item s effective demand as a function of other items order quantities we derive first order optimality conditions for the centralized model in addition to pure strategy nash equilibrium conditions and uniqueness conditions of the equilibria for the competitive model we further develop gradient based gb and iteration based ib algorithms to solve the centralized and competitive models respectively a computational study verifies the effectiveness of the proposed algorithms the computational results show that a larger cross selling effect leads to a larger order quantity in a centralized nv model but a smaller order quantity in a competitive nv model and a larger positive correlation between items demands leads to higher profits with smaller order quantities in both models moreover nvs will order more items if the demand variance is greater however resulting in lower profits in a competitive situation one will prefer smaller order quantities than in a centralized decision situation

inventory management under price based and stockout based substitution abstract we examine a stochastic inventory and pricing problem for a firm that sells two vertically differentiated products the demands for the two products are determined by total random market size and the customers net utility from buying the two products which is determined by the products quality attributes the individual quality valuation unknown to the firm and the selling prices in case the preferred product is out of stock customers may be willing to buy a substitute instead if their net utility is non negative therefore we analyze an inventory and pricing model considering price based and stockout based substitution we show that the demand function is not continuous in price by decomposing the profit function into different price regimes we are able to derive closed form expressions for the stockout based substitution rates upward and downward substitution and the optimal inventory levels under exogenous pricing under endogenous pricing we find that the profit function is not necessarily unimodal however we show that a unique solution exists for the integrated price and inventory problem under price based substitution only numerical results reveal that not considering stockout based substitution i leads to lower profit margins for high quality products and ii may cause severe supply demand mismatches throughout the entire assortment finally we show the performance of two approximated pricing policies

incorporating contemporaneous residual relationships for security prices abstract using a recent procedure developed by jalilvand and kryzanowski 1985 to capture the contemporaneous residual dependencies in a system of regression equations this paper tests the impact of such residual based relationships in explaining security prices utilizing a multi industry sample of securities over two non overlapping periods the empirical findings show that not only are these contemporaneous residual relationships statistically significant but their inclusion significantly improves the explanatory power of the underlying return generating model

a classification of the literature on the planning of substitutable products abstract a company s assortment of products and corresponding inventory levels are constrained by available resources such as production capacity storage space and capital to acquire the inventory thus customers may not always be able to find a most preferred product at the time of purchase this unsatisfied demand is often substituted with an alternative in the extant literature there have been an increasing number of studies that consider product substitution when planning product assortment inventory and capacity in conjunction with pricing in this paper we classify the literature on the planning of substitutable products published in the major om and marketing journals during the past thirty years 1974 2013 and present a comprehensive taxonomy of the literature one criterion is adopted to discuss modeling objectives and three major criteria are provided to define the nature of product substitution including substitution mechanism substitution decision maker and direction of substitutability we also identify research gaps to provide guidance for related research in the future

exchange rates and news a comment abstract although in a world with more than two countries the error term in standard exchange market efficiency tests will be correlated across exchange rates such information cannot be exploited in tests of market efficiency since the relevant information variables are the same in all equations and thus seemingly unrelated regression estimates are the same as ordinary least squares estimates

optimizing product assortment under customer driven demand substitution abstract the problem of product assortment and inventory planning under customer driven demand substitution is analyzed and a mathematical model for this problem is provided in this paper realistic issues in a retail context such as supplier selection shelf space constraints and poor quality procurement are also taken into account the performance of three modified models one that neglects customers substitution behavior another that excludes supplier selection decision and one that ignores shelf space limitations are analyzed separately with computational experiments the results of the analysis demonstrate that neglecting customer driven substitution or excluding supplier selection or ignoring shelf space limitations may lead to significantly inefficient assortments the effects of demand variability and substitution cost on optimal assortment and supplier selection decisions as well as on the optimal revenue are also investigated the main contribution of this paper is the development of a practical and flexible model to aid retailers in finding optimal assortments to maximize the expected profit

inventory decisions for substitutable products with stock dependent demand abstract we study a retailer s inventory policy for two products the products are substitutable and have inventory dependent demand so a higher inventory level of a product increases its sales we model the joint effect of demand stimulation and product substitution on inventory decisions by considering a single period stochastic demand setting we provide the first order optimality conditions for the profit maximizing order quantities and interpret them using marginal analysis we also consider two heuristic solutions that separately account for either demand stimulation or product substitution our numerical analysis reveals that the optimal policy by appropriately using sales information that quantifies substitution and demand stimulation can produce significantly higher profits the profit benefits are lessened under certain circumstances such as when the two products have similar critical fractile values suggesting that in such instances the heuristics may be used effectively

exchange rate returns news and risk premia abstract using a new survey data set of matched exchange rate and interest rate expectations for eight currencies relative to the german mark we examine empirically the relationship between exchange rate returns news and risk premia news on interest differentials enters significantly in equations for the difference between the spot rate and the lagged forward rate for the british pound japanese yen spanish peseta and the us dollar an unexpected rise in the interest rate differential tends to strengthen the domestic exchange rate for each of these currencies we also find significant effects of our ex ante measure of the risk premium in addition we investigate the effect of lagged interest rate differentials as a proxy for the risk premium and find that they do not capture time varying risk premia as is widely suggested in the literature but probably reflect a peso problem learning about a policy change a market inefficiency or a combination of these factors

incorporating one way substitution policy into the newsboy problem with imprecise customer demand this paper presents an approach for solving an inventory model for single period products with maximizing its expected profit in a fuzzy environment in which the retailer has the opportunity for substitution though various structures of substitution arise in real life in this study we consider the fuzzy model for two item with one way substitution policy this one way substitutability is reasonable when the products can be stored according to certain attribute levels such as quality brand or package size again to describe uncertainty usually probability density functions are being used however there are many situations in real world that utilize knowledge based information to describe the uncertainty the objective of this study is to provide an analysis of single period inventory model in a fuzzy environment that enables us to compute the expected resultant profit under substitution an efficient numerical search procedure is provided to identify the optimal order quantities in which the utilization of imprecise demand and the use of one way substitution policy increase the average expected profit the benefit of product substitution is illustrated through numerical example

flexible exchange rates prices and the role of news lessons from the 1970s recent experience with flexible exchange rate systems has led to renewed interest in the operation of foreign exchange markets as reflected in many recent studies of the principal determinants of exchange rates the 1970s witnessed the dramatic alteration of the international monetary system from a regime of pegged exchange rates which prevailed for about a quarter of a century since the bretton woods conference into a regime of flexible though managed rates as a consequence of the emergence of the new legal and economic system traders national governments and international organisations were confronted with new economic problems choices and instruments during the 1970s ex change rates fluctuated widely and inflation rates accelerated the international monetary system had to accommodate extraordinarily large oil related shocks which affected trade flows in goods and assets huge oil payments had to be recycled uncertainties concerning future developments in international politics reached new heights and the prospects for the world economy got gloomier these developments placed unprecedented pressures on the markets for foreign exchange as well as on other asset markets they were associated with a large slide in the value of the us dollar and resulted in speeding up the creation of new institutions like the european monetary system which provided the formal framework for the management of exchange rates among members

a single period inventory placement problem for a supply chain with the expected profit objective consider the expected profit maximizing inventory placement problem in an n stage supply chain facing a stochastic demand for a single planning period for a specialty item with a very short selling season each stage is a stocking point holding some form of inventory e g raw materials subassemblies product returns or finished products that after a suitable transformation can satisfy customer demand stocking decisions are made before demand occurs because of delays only a known fraction of demand at a stage will wait for shipments unsatisfied demand is lost the revenue salvage value ordering shipping processing and lost sales costs are proportional there are fixed costs for utilizing stages for stock storage after characterizing an optimal solution we propose an algorithm for its computation for the zero fixed cost case the computations can be done on a spreadsheet given normal demands for the nonnegative fixed cost case we develop an effective branch and bound algorithm

inventory control with an exponential utility criterion a base stock policy is shown to be optimal when a dynamic version of the news vendor model is optimized with respect to an exponential utility criterion

the interdependence of the term structure of eurocurrency interest rates abstract this paper investigates the interdependence of the term structure of eurocurrency interest rates our results suggest that when the central banks of switzerland and west germany increased their intervention in foreign exchange markets after the october 1979 monetary policy regime change in the usa a significant relationship developed between short term eurodollar interest rates and long term euromark and swiss eurofranc interest rates common cross country exchange rate expectation errors are exploited to improve the efficiency of the estimates using zellner s seemingly unrelated regressions

the forward rate as a predictor of the future spot rate a stochastic coefficient approach this paper develops a stochastic coefficient model to examine the unbiased forward rate hypothesis for the period january 1974 to august 1983 tests from the full sample estimations confirm the null hypothesis however the re sults from the brown durbin evans 1975 test and the chow test indic ate that the exchange rate behavior departs from parameter constancy using joint rolling regressions for the subsample estimations the a uthor finds evidence that the unbiasedness hypothesis in most cases s hould be rejected and that the estimated parameters sensitive to new information vary through different subsample periods the out of sa mple test concludes that incorporation of the stochastic properties o f the parameters into the model improves accuracy of exchange rate pr edictions copyright 1988 by ohio state university press

the impact of product substitution on retail merchandising abstract we analyze the impact of product substitution on two key aspects of retail merchandising order quantities and expected profits to perform this analysis we extend the basic news vendor model to include the possibility that a product with surplus inventory can be used as a substitute for out of stock products this extension requires a definition and an approximation for the resulting effective demand under substitution a service rate heuristic is developed to solve the extended problem the performance of this heuristic is evaluated using an upper bound generated by solving the associated lagrangian dual problem our analysis suggests that this heuristic provides a tractable and accurate method to determine order quantities and expected profits under substitution we apply this heuristic to examine how the level of demand uncertainty and correlation and the degree of substitution between products affect order quantities and expected profits under substitutable demand in addition we use the heuristic to better understand the mechanism by which substitution improves expected profits

technical note a multiperiod model of inventory competition this paper explores when it is important for firms to consider stockout based substitution and competitor s inventory levels in making inventory decisions in the context of a duopoly model to address this question we consider a model where two newsvendors sell substitutable products in a market with aggregate market demand d the two firms get a proportion p and 1 p of this demand where p is random we characterize the equilibrium inventory levels of the two firms in a single period model and show the striking property that under certain reasonable conditions on the cost parameters the two firms ignore their competitor s inventory levels and potential substitution demand i e their inventory decisions are decoupled furthermore we show under slightly more restrictive conditions on the cost parameters that the single period results can be extended to the case where d is random finally we extend the decoupling property to a multiperiod periodic review scenario and show that the resulting nash equilibrium can be characterized simply as the solution to a single product dynamic newsvendor problem that ignores substitution demand

var as a risk measure for multiperiod static inventory models abstract this paper explores the possibility to use value at risk var in the context of inventory management var is being used more and more in financial management as a natural measure of the risk taken with a given position in the framework of inventory management it can work as well after having built a decision model where the choice concerns the quantity to be ordered to face a random demand in order to optimize the expected result an expected cost to be minimized or an expected profit to be maximized the model explores the probability distribution of the result both via analytical methods and via simulation methods the analytical exploration of this problem has originated a general method to deduce from inequalities for distribution functions which are based on the expected value related tail inequalities which are particularly useful for var problems where only one tail is involved

floating exchange rates expectations and new information abstract this paper analyzes the relationship between forward exchange rates future spot rates and new information a stochastic model of exchange rate determination is used to formally show how unanticipated changes in the exchange rate determinants or news affect the spot rate the empirical analysis indicates that new information plays an important role in explaining the market forecasting error or difference between the spot rate and the forward rate determined in the previous period

a note on probability distributions with increasing generalized failure rates distributions with an increasing generalized failure rate igfr have useful applications in pricing and supply chain contracting problems we provide alternative characterizations of the igfr property that lead to simplify verifying whether the igfr condition holds we also relate the limit of the generalized failure rate and the moments of a distribution

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

learning and the exchange rate exchange rate responses to money announcements in the early 1980s abstract the paper develops a monetary model of exchange rate determination with transitory monetary shocks and bayesian learning the model implies that exchange rate responses to monetary surprises are time varying and asymmetric furthermore the two variables become increasingly negatively correlated as beliefs converge an empirical section reexamines the evidence of dollar exchange rate responses to monetary announcements in the 1979 1984 period during which two monetary reforms took place in the usa there is strong support for the presence of learning behavior during the october 1979 to october 1982 period in the german mark and japanese yen equations

foreign exchange market efficiency tests implications of recent empirical findings abstract the recent empirical literature on the efficiency of the foreign exchange market has been characterized by strikingly contradictory conclusions drawn from similar empirical evidence these contradictions result because 1 different maintained hypotheses are held and 2 different criteria e g micro versus macroeconomic are used to judge the evidence in this survey we organize the empirical literature under several headings the presence of risk premiums empirical regularities in regression tests profitable trading rules and advanced econometric techniques in integrating this material we consider the implications of the current evidence for investors forecasters policy makers and theorists

a model of exchange rate dynamics this model treats the exchange rate as an asset price that depends on expectations concerning exogenous real and monetary factors that will affect relative prices and absolute price levels in future periods changes in exchange rates reflect both expected changes in these exogenous factors and changes in expectations occasioned by new information the model explains the random component in exchange rate behavior the source of divergences from purchasing power parity the anticipatory response of exchange rates to future expected disturbances and the causes of exchange rate overshooting

bilateral exchange rates and risk premia abstract the paper develops a theoretical model of the risk premium in a bilateral exchange rate representative agents in both countries are assumed to hold open positions in foreign exchange together with risky assets denominated in their own currencies also past surpluses in the current account of the balance of payments lead to net foreign asset positions which may partially be covered in the forward markets our two period mean variance model for optimizing investors is combined with standard assumption about the behavior of real exchange rates to give a reduced form equation for the discrepancies between spot rates and lagged forward rates the model is tested for the dollar dm dollar sterling and dollar yen exchange rates using monthly data for the period 1976 86 the null hypothesis of no risk premium is rejected for each of the currencies reported

decision bias in the newsvendor problem with a known demand distribution experimental evidence in the newsvendor problem a decision maker orders inventory before a one period selling season with stochastic demand if too much is ordered stock is left over at the end of the period whereas if too little is ordered sales are lost the expected profit maximizing order quantity is well known but little is known about how managers actually make these decisions we describe two experiments that investigate newsvendor decisions across different profit conditions results from these studies demonstrate that choices systematically deviate from those that maximize expected profit subjects order too few of high profit products and too many of low profit products these results are not consistent with risk aversion risk seeking preferences prospect theory preferences waste aversion stockout aversion or the consequences of underestimating opportunity costs two explanations are consistent with the data one subjects behave as if their utility function incorporates a preference to reduce ex post inventory error the absolute difference between the chosen quantity and realized demand two subjects suffer from the anchoring and insufficient adjustment bias feedback and training did not mitigate inventory order errors we suggest techniques to improve decision making

inventory pooling with environmental constraints using copulas abstract pooling is a best practice in inventory management for economic objectives in this paper we investigate whether pooling stays advantageous if environmental sustainability is considered in addition to the economic performance i e we analyze whether pooling could have a negative impact on the environment and evaluate the resulting trade off between economic and environmental performance within the newsvendor framework we consider three pooling models pooling via centralized ordering physical centralization including inventory allocation to the retailers with priority allocation and transshipments in addition we include environmental constraints based on carbon emissions covering all manufacturing and logistics operations of the product we characterize the optimal policy of the pooling models with emission constraints make a detailed comparison between the models and compare them to the decentralized i e no pooling case using copulas to model the joint distribution of dependent demands we prove that the profit decreases with increasing demand dependence further if the environmental constraint is binding optimal inventory level and emissions decrease with increasing demand dependence and pooling harms the environment compared to the case of no pooling additionally we numerically evaluate the impact of copulas and characterize when the economic and environmental performance of pooling can be balanced

multi product newsvendor problem with value at risk considerations abstract we consider the single period stochastic inventory newsvendor problem with downside risk constraints the aim in the classical newsvendor problem is maximizing the expected profit this formulation does not take into account the risk of earning less than a desired target profit or losing more than an acceptable level due to the randomness of demand we utilize value at risk var as the risk measure in a newsvendor framework and investigate the multi product newsvendor problem under a var constraint to this end we first derive the exact distribution function for the two product newsvendor problem and develop an approximation method for the profit distribution of the n product case n 2 a mathematical programming approach is used to determine the solution of the newsvendor problem with a var constraint this approach allows us to handle a wide range of cases including the correlated demand case that yields new results and insights the accuracy of the approximation method and the effects of the system parameters on the solution are investigated numerically

the setting of profit targets for target oriented divisions abstract setting profit targets and striving to achieve them is fundamental to business survival and success however there has been little research on modeling profit target setting in this paper we study analytic target setting under a common business scenario where a firm is in control of multiple divisions both the firm and the divisions maximize the profit probability i e the probability of achieving some given profit target the firm sets a profit target for each division which then acts as a price setting newsvendor we first obtain the optimal order quantity the optimal retail price and the maximal profit probability of a single division given its assigned target we then derive the firm s profit probability and focus on two specific cases to gain more managerial insights in the first case of fair target setting we show that when each division s demand distribution has an increasing failure rate if a division has a relatively high low production cost its assigned profit target decreases increases with regard to its price elasticity in the second case if the firm is in control of two identical divisions each division s optimal profit target is just half of the firm s profit target when the price elasticity is two or more regardless of production cost and demand distribution

assortment planning and inventory decisions under a locational choice model we consider a single period assortment planning and inventory management problem for a retailer using a locational choice model to represent consumer demand we first determine the optimal variety product location and inventory decisions under static substitution and show that the optimal assortment consists of products equally spaced out such that there is no substitution among them regardless of the distribution of consumer preferences the optimal solution can be such that some customers prefer not to buy any product in the assortment and such that the most popular product is not offered we then obtain bounds on profit when customers dynamically substitute using the static substitution for the lower bound and a retailer controlled substitution for the upper bound we thus define two heuristics to solve the problem under dynamic substitution and numerically evaluate their performance this analysis shows the value of modeling dynamic substitution and identifies conditions in which the static substitution solution serves as a good approximation