the role of aggregation in estimating the effects of private school competition on student achievement abstract this paper investigates possible reasons for the disparity in results in the private school competition literature in particular the focus is on the data set the grade range and level of aggregation of the competition variable and on the choice of ols or iv estimation strategies the results show that the size and significance of the competition variable depends on each of these attributes although the grade range of the competition variable has a slightly smaller impact than the others private school competition does not have a consistently positive significant effect on student achievement

a fuzzy vendor managed inventory of multi item economic order quantity model under shortage an ant colony optimization algorithm abstract in this study a multi item economic order quantity model with shortage under vendor managed inventory policy in a single vendor single buyer supply chain is developed this model explicitly includes warehouse capacity and delivery constraints bounds order quantity and limits the number of pallets not only the demands are considered imprecise but also resources such as available storage and total order quantity of all items can be vaguely defined in different ways an ant colony optimization is employed to find a near optimum solution of the fuzzy nonlinear integer programming problem with the objective of minimizing the total cost of the supply chain since no benchmark is available in the literature a genetic algorithm and a differential evolution are developed as well to validate the result obtained furthermore the applicability of the proposed methodology along with a sensitivity analysis on its parameter is demonstrated using five numerical examples containing different numbers of items

joint pricing and ordering policy for two echelon imperfect production inventory model with two cycles abstract this study deals with an imperfect epq economic production quantity price dependent inventory model over two types of cycles in the first cycle the retailer sells only good product with actual price and in the second he sells the products with a discount price in the production run time the non conforming items are produced at a random rate and they are reworked after the regular production run time and the reworked items are almost perfect as good as original quality items the retailer starts the second cycle when a certain percent of good items are left to him after the completion of regular production the retailer continues simultaneously two cycles up to which both types of the products are available to him now our objective is to find out optimal ordering lot size and optimal price for which the profit of the integrated model is maximum also we check the best strategy of retailer for the time of starting second cycle a numerical example is provided to illustrate the behavior and application of the model

an inventory model for deteriorating items with shortages and time varying demand abstract a deterministic inventory system for items with a constant deterioration rate is studied demand varies in time and it is assumed that it follows a power pattern shortages are allowed and backlogged the ordering cost the holding cost the backlogging cost the deteriorating cost and the purchasing cost are considered in the inventory management an approach is proposed to minimize the total cost per inventory cycle this cost depends on two decision variables the time at which the inventory level falls to zero and the length of the scheduling period numerical examples illustrate the theoretical results

economic order quantity models for imperfect items with buy and repair options abstract one of the celebrated extensions of the economic order production quantity eoq epq model is one that assumes a received shipment contains a fraction of imperfect non conforming quality items where these items detected by 100 screening are sold as a single batch at a discounted price this paper revisits this model salameh and jaber 2000 int j prod econ 64 1 59 64 and extends it by assuming that a shipment is coming from a distant supplier and therefore it is not feasible to replace the imperfect items with an additional order to the same supplier to address this restriction two models are presented the first assumes that imperfect items are sent to a repair shop who charges a cost plus a markup margin while the second model assumes that imperfect items are replaced by good ones from a local supplier at a higher cost the inventory environment assumed in this paper is relevant in todays globalised supply chains thus practical implications of the problem faced are discussed numerical results are also presented and discussed the results show that there exists a threshold value of the unit purchase cost of an emergency ordered item and a fraction of defectives to which it is decided to either buy or repair

a model of tourism destination choice a theoretical and empirical analysis abstract in recent years tourism has become one of the fastest growing sectors of the world economy and is widely recognised for its contribution to regional and national economic development the main aim of the paper is to propose a methodological framework within which the impact of characteristics of a tourism product on foreign travel can be captured and analysed this is achieved by combining the lancasterian product characteristics approach with the koppelman s consumer transportation model within the proposed model the characteristics of the tourism product destination including quality of service advertising and political instability are combined to generate a perception feeling regarding the tourism destination in the mind of the tourists in order to measure these perceptions feelings and hence develop a preference ordering the model is estimated by utilising a conditional logit analysis the analysis is based on primary data collected from tourists visiting cyprus the conditional logit model generates the probability of revisit given the characteristics of tourists and the cyprus tourism product the paper extends further the lancaster product characteristics framework as applied to tourism by rugg rev econom stat 55 1 1973 64 morley ann tourism res 19 1992 250 and papatheodorou ann tourism res 28 2001 164 by including the neglected but from any viewpoint important political instability characteristic that is attached to the tourist product of cyprus the inclusion of product characteristics attributes in tourism analysis appear to strongly contribute towards the better understanding of travel choice behaviour

an economic order quantity model with partial backordering and all units discount abstract the classic economic order quantity model assumes that the unit purchasing cost is not based on the order quantity in practice a supplier may offer purchasers an all units discount we develop a model and solution procedure for the eoq with all unit discounts and partial backordering at a constant rate we show and illustrate with a numerical example how that model can be used to find the solution for the eoq with discount and full backordering a multi factor experiment is used to gain insights into the improvement in performance of the proposed procedure relative to using the basic eoq or the eoq with full backordering and to identify the model parameters that have the greatest impact on the model s performance

ford whitman harris and the economic order quantity model ford whitman harris first presented the familiar economic order quantity eoq model in a paper published in 1913 even though harris s original paper was disseminated widely it apparently was unnoticed for many years before its rediscovery in 1988 during this period much confusion developed over the origin of the eoq model this paper explores the early literature on this model and traces the evolution of the confusion it also sketches the remarkable life of harris who made contributions as an engineer inventor author and patent attorney even though he received no formal education beyond high school harris s original 1913 essay is reprinted following this paper

joint economic lot sizing problem for a three layer supply chain with stochastic demand abstract this paper considers the joint economic lot sizing problem jelp for multi layer supply chain with multi retailers and single manufacturer and supplier the paper extends the work of ben daya et al 2013 and relaxes the assumption of deterministic demand and constant holding and ordering costs the paper proposes modifying four computational intelligent algorithms to solve mixed integer problems and compares their performance for solving the problem at hand the paper further compares between adopting a centralized safety stock policy versus a decentralized policy results showed cuckoo search to outperform other tested algorithms and also favored adopting a centralized policy

a note on optimal replenishment policies for non instantaneous deteriorating items with price and stock sensitive demand under permissible delay in payment abstract soni 2013 int j prod econ 146 1 259 268 proposed optimal replenishment policies for non instantaneous deteriorating items i e the product starts deteriorating after a period of no deterioration with price and stock sensitive demand with a stock dependent demand it is desirable to have non zero ending inventory due to potential profit resulting from the increased demand however soni 2013 int j prod econ 146 1 259 268 treated those ending inventory as fresh stocks to go through another period of non deterioration again additionally he assumed for simplicity that the replenishment cycle time t must be longer than the period of non deterioration t d i e t t d in reality one should consider all possible replenishment cycle time to maximize the profit in this note we complement the shortcomings of his model by i selling those ending inventory as salvages and ii considering all possible replenishment cycle time which may be shorter than the period of non deterioration with these modifications the repeatability of the replenishment cycle is ensured and the applicability of soni s model is strengthened the numerical examples indicate that the global optimal solution is indeed possible in the case of t t d

optimal lot size for a production inventory system with partial backlogging and mixture of dispatching policies abstract in this paper we study a production inventory model for a single product where shortages are partially backlogged both the backorder cost and the lost sale cost depend on a fixed cost and a cost proportional to the shortage time we assume a mixture between the dispatching policies known as lifo last in first out and fifo first in first out in the discipline of service to fill the backlogged demand by using a sequential optimization procedure we determine in a closed form the optimal production policies and the optimal profit for all the possible cases obtained from the developed model we show how this new model generalizes several inventory models proposed in the literature finally numerical results are presented to analyze the sensitivity of the optimal policies with respect to changes in some parameters of the system

lot sizing and lead time decisions in production inventory systems traditionally lot sizing decisions in inventory management trade off the cost of placing orders against the cost of holding inventory however when these lot sizes are to be produced in a finite capacity production inventory system the lot size has an important impact on the lead times which in turn determine inventory levels and costs in this paper we study the lot sizing decision in a production inventory setting where lead times are determined by a queueing model that is linked endogenously to the orders placed by the inventory model assuming a continuous review s s inventory policy we develop a procedure to obtain the distribution of lead times and the distribution of inventory levels when lead times are endogenously determined by the inventory model this procedure allows to determine the optimal inventory parameters within the class of s s policies that minimize the expected ordering and inventory related costs over time we numerically show that ignoring the endogeneity of lead times may lead to inappropriate lot sizing decisions and significantly higher costs this cost discrepancy is very outspoken if the lot size based on the economic order quantity deviates significantly from desirable production lot sizes in these cases the endogenous treatment of lead times is of particular importance

school expenditures and post schooling earnings evidence from high school and beyond studies based on inputs measured at the state level generally report that school expenditures have substantial effects on students adult wages whereas studies based on less aggregated measures report small effects the author uses wage data from high school and beyond to analyze this discrepancy and to estimate the effect of school expenditures on students post schooling earnings the author finds that the discrepancy in the literature stems mostly from two factors measurement error in district level expenditures and omitted state effects in the earnings regression the author also finds that the effect of school expenditures on earnings is significant but small a 10 increase in school spending would increase students adult wages by only 0 68 copyright 1996 by mit press

an eoq model with partial backordering and advance payments for an evaporating item abstract in the classic economic order quantity model the purchasing cost of an order is paid at the time of its receipt in some cases retailers ask purchasers to pay all or a fraction of the purchasing cost in advance and may allow them to divide the prepayment into several equal sized parts in this paper an economic order quantity model for an evaporating item with partial backordering and partial consecutive prepayments is developed with a real case study of a gasoline station real numerical examples illustrate the proposed model and the solution method

a periodic review lot sizing problem with random yields disruptions and inventory capacity this paper examines a periodic reviewed lot sizing problem with random yields disruptions and limited inventory capacity to characterise the continuous production an additive random yield model is considered rather than a multiplicative one disruptions cause breakdowns to production inventory capacity is included since the production has to be shut down when the inventory buffer is full both disruptions and shutdowns lead to a start up cost and a stochastic lead time to recover the production these compound factors of uncertainty are encountered in practical planning decisions in process industries we review the existing random yield models which are then compared with the additive model with a linear production cost the additive model has an order up to policy to be optimal disruptions deteriorate the expected actual production quantity and the fill rate dramatically even though the optimal order up to level increases compared with the cases of no disruption considering inventory capacity makes the problem to be a non convex dynamic programming problem numerical analysis shows that the performance is dramatically deteriorated when the inventory capacity is rather tight which indicates the importance of selecting a proper inventory capacity to reduce the negative impacts and avoid redundant investment on capacity moreover the start up cost plays an important role in determining the level of inventory capacity

an inventory model with both stock dependent demand rate and stock dependent holding cost rate abstract in this paper we develop an inventory model under a stock dependent demand rate and stock dependent holding cost rate with relaxed terminal conditions shortages are allowed and partially backlogged in the model the purpose of this study is to determine the optimal order quantity and the ending inventory level such that the total profit per unit time is maximized for the retailer we first establish a proper model for a mathematical formulation then we develop several theoretical results and provide the decision maker with an algorithm to determine the optimal solution finally numerical examples are provided to illustrate the solution procedure and a sensitivity analysis of the optimal solution with respect to major parameters is carried out

optimal lot sizing integration policy under learning and rework effects in a manufacturer retailer chain abstract most research in economic manufacturing order quantity management assumes that all products are of perfect quality and are produced at a constant production rate one result of this assumption is that the number of units produced in a given period is constant which is not the case in real life most production systems produce items which are of perfect quality along with some that are of imperfect quality defective items as well as the learning effect affect production and inventory costs thereby shaping the performance of the manufacturer retailer chain the present study uses the nash stackelberg and cooperation games to model an imperfect production system to investigate the combined effects of lot sizing size integration the learning effect imperfect production and the rework process on a manufacturer retailer channel this study also demonstrates the optimal properties of the proposed models develops a search algorithm for obtaining optimal solutions and conducts a numerical study to seek structural and quantitative insights into the structure of the proposed models in addition it analyzes the sensitivity of the solutions in relation to the major parameters

the public choice of educational choice the very small literature explaining i how citizens have voted in two california voucher referenda ii how legislators have voted on voucher bills in the state of florida and the us congress and iii the variation across states in charter school provisions is summarized new empirical evidence documenting the cross state variation in the success of voucher referenda and voucher bills is examined voucher bill characteristics and state characteristics play important roles voucher bills have been passed only in the more conservative republican states and almost all of the successful voucher programs have been targeted at large struggling school districts

celebrating a century of the economic order quantity model in honor of ford whitman harris abstract this writing presents a brief introduction to the papers included in the special issue celebrating a century of the economic order quantity model in honor of ford whitman harris published by the international journal of production economics forty one papers covering an extensive scope of inventory management have been incorporated in this volume from contributing authors from 20 countries located in america asia europe and africa this special issue also provides a basis for new directions in inventory management research

revisiting foundations in lot sizing connections between harris crowther monahan and clark abstract while many review articles exist on deterministic lot sizing models used in the context of price and quantity discounts buyer vendor coordination supply chain management and joint economic lot sizing problems they do not convey the impact of important findings which date back to at least 2002 or in hindsight to 1984 as a result many recent articles still model the financial implications of lot sizing decisions without having the assurance that these models would help the firm s involved in maximising the net present value npv this paper therefore reviews these findings while adding also its own contributions as to convey the general importance to lot sizing theory we show that the underlying principles used in the four key articles that have led to a division in modelling approaches are in fact all in line with npv and argue that therefore there should not be these discrepancies that currently persist in the literature we establish the connections between these four strands of the literature using the solution to a simple variation of harris eoq model deriving thereby results from boyaci and gallego 2002 and beullens and janssens 2011 but showing their general applicability to any type of supply chain structure the breath of implications to deterministic lot sizing theory is illustrated using practical examples we present a stochastic version of the model of crowther 1964 which is arguably the least understood and applied model but on the other hand the most important one in realising how these modelling strands can be unified

the economics of schooling production and efficiency in public schools n recent years public and professional interest in schools has been heightened by a spate of reports many of them critical of current school policy these policy documents have added to persistent and long standing concerns about the cost effectiveness and fairness of the current school structure and have made schooling once again a serious public issue as in the past however any renewed interest in education is likely to be short lived doomed to dissipate as frustration over the inability of policy to improve school practice sets in this frustration about school policy relates directly to knowledge about the educational production process and in turn to underlying research on schools although the educational process has been extensively researched clear policy prescriptions flowing from this research have been difficult to derive 2 there exists however a consistency to the research findings that does have an immediate application to school policy schools differ dramatically in quality

economic production quantity models for deteriorating items with up stream full trade credit and down stream partial trade credit abstract in practice in order to reduce default risks with credit risk customers a seller e g a manufacturer or a retailer frequently requests its credit risk customers to pay a fraction of the purchase amount at the time of placing an order as collateral deposit and then grants a permissible delay on the outstanding balance i e a down stream partial trade credit by contrast the seller usually receives a permissible delay on the entire purchase amount from the supplier i e an up stream full trade credit in this paper we propose an economic production quantity epq model for deteriorating items in a supply chain with both up stream and down stream trade credit financing by using fractional programming results we can prove that the optimal solution not only exists but also is unique moreover we propose three discrimination terms to identify the optimal solution among possible alternatives finally some numerical examples are presented to highlight the theoretical results and managerial insights

retailer s economic order quantity when the supplier offers conditionally permissible delay in payments link to order quantity abstract trade credit financing is increasingly recognized as an important strategy to increase profitability in inventory management we revisit an economic order quantity model under conditionally permissible delay in payments in which the supplier offers the retailer a fully permissible delay of m periods i e there is no interest charge until m if the retailer orders more than or equal to a predetermined quantity w however if the retailer s order quantity is less than w then the retailer must make a partial payment to the supplier and enjoy a permissible delay of m periods for the remaining balance in this paper we extend the mentioned eoq under conditionally permissible delay in payments to complement some shortcomings of the model by contrast to the differential calculus method we propose a simple arithmetic geometric method to solve the problem furthermore we establish some discrimination terms to identify the unique optimal solution among three alternatives and explain those theoretical results by simply economical interpretations finally we solve several numerical examples to illustrate the theoretical results and obtain some managerial implications

improved quality setup cost reduction and variable backorder costs in an imperfect production process abstract this paper illustrates the relationship between quality improvement reorder point and lead time as affected by backorder rate in an imperfect production process to reduce the total system cost by optimizing the setup cost lot size lead time reorder point and process quality parameter simultaneously we first consider that the lead time demand follows a normal distribution then we apply the distribution free approach for the lead time demand we prove two lemmas which are used to find optimal solutions for the basic and distribution free models we compare our models with the existing models using numerical examples and show that significant savings over the existing models can be achieved

the carbon constrained eoq model with carbon emission dependent demand abstract currently companies are looking for solutions to reduce carbon emissions associated with their operations operational adjustments such as modifications in batch sizes or order quantities have proven to be an effective way to decrease emissions in this paper a novel model is proposed that takes into account the link between an inventory policy eoq total carbon emissions and both price and environmental dependent demands in the case of an exogenous price two optimal quantities are determined which maximize a retailer s profit and which minimize carbon emissions conditions that allow a company to maximize profit while minimizing emissions and mechanisms that allow a firm to maximize its profit and to decrease its carbon emissions are determined in the case of an endogenous price some empirical results are also discussed when a firm optimizes its profit through both its selling price and its order quantity some experiments match empirical observations on the one hand an environmental strategy is more significant for cheaper and green labeled products on the other hand a public mechanism such as a carbon tax will decrease total and marginal emissions

public education supply and student performance this paper develops a model of public exchange whereby voters and education policy makers exchange with one another within school districts because school district consolidation lowers alternatives to voters parents consolidation is hypothesized to raise public education spending because weakened intergovernmental competition allows policy makers to promote their own utility rather than that of constituents models of public education spending and academic performance are estimated over 1988 1990 while evidence indicates little support for the traditional treatment of the leviathan hypothesis that greater competition lowers public spending this paper argues that education spending by itself does not fully provide a valid test of the leviathan hypothesis since spending by itself does not necessarily indicate the quality of public education programmes empirical evidence indicates that greater numbers of schools and school districts promote higher student achievement as evidenced by higher math and v

optimal policy for an inventory system with power demand backlogged shortages and production rate proportional to demand rate abstract this article analyzes an inventory system for items with time varying demand the way by which demand occurs during the inventory cycle follows a power demand pattern the production of items allows to add stock in the inventory during a replenishment period the production rate is proportional to demand rate shortages are allowed and completely backlogged holding cost shortage cost and order cost are the costs considered in the inventory model the aim consists of the minimization of the total cost per inventory cycle an efficient approach is developed to obtain the optimal scheduling period and the optimal reorder point in addition the economic lot size and the minimum cost of the inventory management is determined some numerical examples are presented for illustrating the proposed inventory model

the influence of distance and prices on the choice of tourist destinations the moderating role of motivations abstract the literature of tourist destination choice pays great attention to the direct impact of the attributes of distance to the destination and prices of the destination but does not reach any consensus around them regarding their inhibitory or attraction effect alternatively our study proposes that the effects of distance and prices are moderated by tourist motivations at the moment of choosing a destination which leads us to make hypotheses to explain this decision through the interaction between destination attributes and the personal motivations of the individual tourists the methodology applied estimates random coefficient logit models which control possible correlations between different destinations and consider tourist heterogeneity the empirical application carried out in spain on a sample of 2127 individuals shows that the dissuasive influence of distance and prices on the selection of destinations is moderated by motivations in the sense that the motivations have a direct increasing the dissuasive effect or inverse reducing the dissuasive effect moderating effect on the influences of distance and prices

choice of ontario high schools and student sorting by ability to what extent can offering more choice in schooling lead to cream skimming or the sorting of students by ability i study whether increased choice leads to student sorting by ability into high schools in the greater toronto area on average 41 of students opt out of the high school to which they would normally be assigned based on their residence students are more likely to opt out in areas where accessibility to other schools is greatest due to population density and explicit open enrolment policies while students of higher ability are generally more likely to opt out an interaction term between school choice and ability is insignificant suggesting that increased choice does not have differential impacts by student ability findings are robust to changes in assumptions about instrument exogeneity

how many parts to make at once reprinted from factory the magazine of management volume 10 number 2 february 1913 pp 135 136 152 interest on capital tied up in wages material and overhead sets a maximum limit to the quantity of parts which can be profitably manufactured at one time set up costs on the job fix the minimum experience has shown one manager a way to determine the economical size of lots

the attribute carryover effect what the runner up option tells us about consumer choice processes the process used to differentiate a top choice from a runner up can result in a preference reversal among nonselected alternatives which we term the attribute carryover effect a series of three experiments demonstrate that a phased choice process can shift attribute preferences if the top choice is unavailable consumers with weak attribute preferences are likely to reject their explicitly identified second choice the runner up option instead these consumers choose an option that may not meet the initial screening criteria but that does share a desirable differentiating feature with the unavailable top choice judgment data indicate that this preference reversal is due to increased salience of the differentiating attribute during the last phase of the original choice which carries over into the subsequent choice these findings augment our understanding of consumer choice processes and heighten our ability to predict choice outcomes under situations in which a chosen option is unattainable

the influence of private school enrollment on public school performance school choice reform refers to changes that allow parents greater freedom to choose schools for their children school choice reform is contentious because it fundamentally alters the environment in which public and private schools operate and could result in significant changes for both demanders and suppliers of education this article develops a model of public education with imperfect exit to predict how private school enrollment influences performance of public schools empirical evidence from data on all private and public schools in california provides substantial support for the hypothesis that public school test scores are inversely related to private school enrollments and charter school enrollments when private and charter schooling reflects exiting by parents unhappy with local public schools implications regarding how expanded private school choice might influence public school performance in california and elsewhere are discussed

optimal ordering and pricing policy for demand functions that are separable into price and inventory age abstract we formulate and analyze two models for determining the optimal pricing order quantity and replenishment period for items whose demand function is separable into components of price and inventory age the first model assumes a multiplicative demand function we provide conditions which are satisfied by most common price dependent demand functions to reduce the three variable profit maximization problem into a single variable problem which can be solved using an efficient line search method next we show that a genuine additive model cannot exist and instead suggest and analyze a pseudo additive model however this model is more limited than the multiplicative model in its ability to incorporate various combinations of price and inventory age effects and reduction of the maximization problem into a single variable problem is more complicated except in the case of a linear price effect which is further analyzed for both models we show that the optimal solution satisfies the first order condition for equilibrium under a monopoly with a modification that includes inventory holding costs we solve numerical examples to illustrate the solution procedures

a century of evolution from harris s basic lot size model survey and research agenda abstract determining the economic lot size has always represented one of the most important issues in production planning this problem has long attracted the attention of researchers and several models have been developed to meet requirements at minimum cost in this paper we explore and discuss the evolution of these models during one hundred years of history starting from the basic model developed by harris in 1913 up to today following harris s work a number of researchers have devised extensions that incorporate additional considerations the evolution of eoq theory strongly reflects the development of industrial systems over the past century here we outline all the research areas faced in the past by conducting a holistic analysis of 219 selected journal papers and trying to give a comprehensive view of past work on the eoq problem finally a new research agenda is proposed and discussed

sustainable newsvendor models under trade credit abstract governments and industry are actively seeking means of reducing global warming the management of supply chains while taking into account the effects on the environment is an important issue therefore we present newsvendor models that take into account carbon emissions trade credit and product recycling in which the credit period affects the risk of default and the demand is uncertain in this paper the objective of these models is to determine the optimal ordering quantity credit period and recycle price in order to maximize total profits three carbon emission incentives are taken into account 1 carbon tax 2 direct cap 3 carbon cap and trade we also incorporate risk management methods to limit risk of default providing a solution for each type of carbon emission incentive numerical analysis is used to illustrate the implementation of solutions and the degree to which system parameters affect profits and decision making the results show that higher carbon taxes reduce recycle prices order quantities and total profits increasing the carbon cap leads to increases in recycle price order quantity and total profit a higher carbon price drives down the recycle price order quantity and total profits

does school quality matter returns to education and the characteristics of public schools in the united states this paper estimates the effects of school quality measured by the pupil teacher ratio average term length and relative teacher pay on the rate of return to education for men born between 1920 and 1949 using earnings data from the 1980 census we find that men who were educated in states with higher quality schools have a higher return to additional years of schooling rates of return are also higher for individuals from states with better educated teachers and with a higher fraction of female teachers holding constant school quality measures however we find no evidence that parental income or education affects average state level rates of return

analysis of batch ordering inventory models with setup cost and capacity constraint abstract stochastic periodic review batch ordering inventory problems appear in many industrial settings however few literature deals with the optimal ordering polices for such problems no mention to the inclusion of the fixed ordering cost and the production capacity in this paper we consider a single item periodic review batch ordering inventory system with the consideration of the setup cost and the capacity constraint for each order over a finite planning horizon by proposing several new convex notions we show that a batch based s s policy is optimal for the unlimited ordering capacity case while for the limited ordering capacity case a modified r q policy is optimal for the setting with zero ordering setup cost and a batch based x y band policy for the setting with positive ordering setup cost moreover we analytically study the sensitivity of the policy parameters with respect to the capacity and batch order size and derive the bounds on the optimal policy parameters we further extend our analysis to the infinite horizon setting and show that the structure of the optimal policy remains similar finally the numerical experiments provide some insights into the impact of model parameters on the benefit of reducing the batch size and increasing the ordering capacity and indicate that ignoring batch requirement may lead to a significant cost increment

economic order quantities in production from harris to economic lot scheduling problems abstract this article provides a short historical overview from harris and his economic order quantity eoq formula to the economic lot scheduling problem elsp the aim is to describe the development of the elsp field from the eoq formula to the advanced methods of today in a manner that suits master and graduate students the article shows the complexities difficulties and possibilities of scheduling and producing several different items in a single production facility with constrained capacity the items have different demand cost operation time and set up time set up time consumes capacity and makes the scheduling more complicated idle time makes the scheduling easier but is bad from a practical point of view since it creates unnecessary costs due to low utilisation of the facility a heuristic solution method is used on a small numerical example to illustrate different solution approaches the solution method creates a detailed schedule and estimates the correct set up and inventory holding cost even if the facility works close to its capacity

tourist destination and experience choice a choice experimental analysis of decision sequence effects abstract while many studies have investigated travel motives and modelled holiday destination choices none have directly modelled choice of type of holiday experience and how these two choices interrelate this study tests whether early exposure to geographical destination or experience type information in a decision task influences consumers final choices when choosing a holiday the study compares two choice tasks that have the same instructions and attributes but differ with respect to which attribute is exposed first and is used to label the choice options the destination name or the experience type findings show that early exposure to either attribute enhances the importance of the attribute although the effect is less pronounced for experiences than for destinations the findings are explained using the psychological notions of leader primacy complacency and induced mindset the research conducted in australia shows that sequential effects can be very important in shaping tourism consumption choices and decision making

an eoq model with backorders and rejection of defective supply batches abstract we consider a single echelon inventory installation under the classical eoq with backorders paradigm to study the effects of supply quality on cost performance previous research on imperfect supply quality has focused on variants of the proportional deterministic or random yield problem where supply batches are all accepted and then used after screening any defects in this paper we study an alternative setting where entire supply batches may be defective below quality standards and therefore rejected on arrival note that such supply flow disruptions are analogous to those considered within the economic order quantity with disruptions eoqd area of research we first present an exact model for the system expected cost and show its convexity optimal cost and respective values of the decision variables i e planned order quantity and backorders are then obtained in a closed form interestingly under perfect supply quality all expressions reduce to those of classical eoq analytical and computational results reveal the serious impact of inferior supply quality on system cost as well as the sensitivity of the system parameters

optimal trade credit and lot size policies in economic production quantity models with learning curve production costs abstract in reality a seller e g a supplier or a manufacturer frequently offers his her buyers trade credit e g permissible delay in payment trade credit reduces the buyer s holding cost of inventory and hence attracts new buyers who consider it to be a type of price reduction on the other hand granting trade credit also increases the seller s opportunity cost i e the loss of capital opportunity during the credit period and default risk i e the event in which the buyer will be unable to make the required payments on his her debt obligation in addition it is a well known fact of learning by doing that production cost of a new product declines by a factor of from 10 to 50 percent each time the accumulated production volume doubles therefore we propose an economic production quantity model from the seller s prospective to determine his her optimal trade credit period and production lot size simultaneously in which i trade credit increases not only sales but also opportunity cost and default risk and ii production cost declines and obeys a learning curve phenomenon then the necessary and sufficient conditions to obtain the seller s optimal trade credit and order quantity are derived finally we use some numerical examples to illustrate the theoretical results and to provide some managerial insights

optimal vendor investment for reducing defect rate in a vendor buyer integrated system with imperfect production process this paper investigates a single vendor single buyer integrated production inventory model with stochastic demand and imperfect production process it is assumed that there is an inspection activity on the part of the buyer with a fixed screening rate greater than the demand rate the vendor invests money in order to improve the production process quality and reduce the number of defectives the expected annual integrated total cost is derived under the n shipment policy and an iterative procedure is suggested to determine the optimal decisions the benefit of investment in reducing the defect rate is illustrated by way of numerical examples it is observed that the higher the defect rate the more beneficial the investment numerical studies further explore that an increased demand requires an increased investment to optimize the total cost

optimal replenishment policies for non instantaneous deteriorating items with price and stock sensitive demand under permissible delay in payment abstract this study is motivated by the paper of chang et al international journal of production economics 123 2010 62 68 we extend their inventory model from two aspects 1 the demand rate as multivariate function of price and level of inventory 2 delay in payment is permissible under these assumptions we first formulated a mathematical model and then some useful theoretical results have been derived to characterize the optimal solutions for non zero and zero ending inventory system numerical examples are presented to illustrate the theoretical results the sensitivity analysis of a suitable example is performed and some managerial insights are proposed our analysis revels that it is more beneficial to keep higher inventory level hoping to stimulate more demand even if it results in non zero ending inventory

lot sizing policies for deteriorating items with expiration dates and partial trade credit to credit risk customers abstract in practice a credit worthy retailer frequently receives a permissible delay on the entire purchase amount without collateral deposits from his her supplier i e an up stream full trade credit by contrast a retailer usually requests his her credit risk customers to pay a fraction of the purchase amount at the time of placing an order and then grants a permissible delay on the remaining balance i e a down stream partial trade credit in addition many products such as blood banks pharmaceuticals fruits vegetables volatile liquids and others deteriorate constantly and have their expiration dates however not many researchers have taken the expiration date of a deteriorating item into consideration the purpose of this paper is to establish optimal lot sizing policies for a retailer who sells a deteriorating item to credit risk customers by offering partial trade credit to reduce his her risk the proposed model is a generalized case of many previous models by applying theorems in pseudo convex fractional functions we can easily prove that the optimal solution not only exists but is also unique moreover we propose three discrimination terms which can easily identify the optimal solution among all possible alternatives finally some numerical examples are presented to highlight the theoretical results and managerial insights

dynamic version of the economic lot size model this article originally appeared in management science october 1958 volume 5 number 1 pp 89 96 published by the institute of management sciences a forward algorithm for a solution to the following dynamic version of the economic lot size model is given allowing the possibility of demands for a single item inventory holding charges and setup costs to vary over n periods we desire a minimum total cost inventory management scheme which satisfies known demand in every period disjoint planning horizons are shown to be possible which eliminate the necessity of having data for the full n periods

non public competition and public school performance evidence from west virginia abstractin this study we investigate whether non public school enrolment affects the performance of public school districts if homeschooling and private schools act as competition public school districts test scores should be positively associated with non public enrolment using data on west virginia county school districts and controlling for endogeneity with an instrumental variables approach we find that a one standard deviation increase in relative non public enrolment in a county is associated with statistically significant improvements in public school district test scores our findings thus confirm that non public enrolment and the competition it provides act to improve rather than impede public school performance

economic order quantity for growing items abstract economic order production quantity eoq epq models have generally been presented for manufacturing products incorporating some important features of a specific category of products different eoq epq models have been proposed in literature this study proposes a new class of inventory models i e a model for a specific type of inventory items growing items poultry and livestock are good examples of growing inventory items we begin by proposing a general mathematical model which can be used for different types of growing items followed by a particular mathematical model for a specific type of poultry we calculate the optimal order quantity of the growing items at the start of a growing cycle the optimal length of the growing cycle and the optimal total profit numerical examples are provided for a type of poultry to illustrate the model a sensitivity analysis is presented to study the effect of the main parameters of the model in terms of its decision variables and objective function the results of the sensitivity analysis suggest that production costs are the most crucial parameter

an early classic misplaced ford w harris s economic order quantity model of 1915 the familiar square root formula for the optimal economic order quantity was derived originally by harris in 1915 harris f w 1915 what quantity to make at once the library of factory management vol v operation and costs a w shaw company chicago 47 52 since all citations found to harris s paper over the past 35 years are incorrect it seems that no one has been able to locate the paper during this period the paper s apparent misplacement probably stems from an inaccurate citation given by raymond in 1931 raymond f e 1931 quantity and economy in manufacture mcgraw hill new york harris s paper exemplifies skillful presentation of the concepts of management science and still merits reading today s researcher can learn much from harris s modeling approach and would do well to emulate his expositional clarity and motivational effectiveness

generalized eoq formula using a new parameter coefficient of backorder attractiveness abstract this paper introduces and examines a generalized eoq formula based on the model with linear and fixed backordering costs the new square root formula is a combination of two well known classical models the basic eoq model without stockouts and the eoq model with backorders and linear backordering costs helping to combine the two is a new parameter a fractional coefficient capturing the attractiveness of backorders the coefficient is explained and discussed the paper concludes with a brief discussion of generalizations in eoq models including epq