perishable inventory theory a review this paper reviews the relevant literature on the problem of determining suitable ordering policies for both fixed life perishable inventory and inventory subject to continuous exponential decay we consider both deterministic and stochastic demand for single and multiple products both optimal and sub optimal order policies are discussed in addition a brief review of the application of these models to blood bank management is included the review concludes with a discussion of some of the interesting open research questions in the area

evaluating welfare reform in the united states this paper reviews the economic literature on welfare reform over the 1990s a brief summary of the policy changes is followed by a discussion of the methodological techniques that analyze the effects of these changes on outcomes the paper then critically reviews the econometric and experimental literature on caseload changes labor force changes poverty and income changes and family formation changes a growing body of evidence suggests that recent policy changes have influenced economic behavior and well being one particular set of new style welfare programs seems to show especially promising results with significantly increased work and earnings and reduced poverty

a deterministic inventory model for deteriorating items with stock dependent demand rate abstract a deterministic inventory model is developed by assuming that the demand rate is stock dependent and the items deteriorate at a constant rate the expression for the average net profit over one production run is derived and its optimization with respect to the decision variables q initial stock and t duration of a production cycle is carried out this leads to two highly nonlinear equations which are solved by using a subroutine neqnf in imsl math library in cyber 180 480a computer system the optimal solution so derived is compared with that for the no deterioration 0 case sensitivity of the optimal solution to changes in parameter values is examined several aspects of the functional form for the demand rate are considered in a separate section finally the salient features of the problem and its solution are discussed in brief

securitization and the balance sheet channel of monetary transmission abstract this paper shows that the balance sheet channel of monetary transmission is stronger for us banks that securitize their assets this finding is different in spirit from the widely found negative relationship between financial development and the strength of the lending channel of monetary transmission focusing on the balance sheet channel and using bank level observations we find that securitizing banks are more sensitive to borrowers balance sheets and that monetary policy has a greater impact on this sensitivity for securitizing banks the optimality conditions from a simple partial equilibrium framework suggest that the positive effects of securitization on policy effectiveness could be due to the high sensitivity of security prices to policy rates

an economic lot size model with non linear holding cost hinging on time and quantity abstract this paper develops an economic lot size inventory model where the demand rate depends on the stock level and the cumulative holding cost is non linear on both the quantity and the time they are stored more concretely it is supposed that the demand rate is a concave potential function of the inventory level and the holding cost is potential on both time and quantity moreover shortages are not allowed a general procedure to determine the optimal lot size and the maximum inventory profit is developed also some results about the profitability of the inventory system are presented this work extends several inventory models previously considered in the literature finally numerical examples which help us to understand the theoretical results are also given

firm balance sheets and monetary policy transmission the functioning of internal capital markets in financial conglomerates facilitates a novel identification strategy of the balance sheet channel of monetary policy we look at small subsidiary banks that are affiliated with the same holding company but operate in different geographical areas these banks face the same marginal cost of funds due to internal capital markets but face different borrowers as they concentrate their lending with small local businesses exploring cross sectional variation in local economic conditions across these subsidiaries we investigate whether borrower creditworthiness influences the response of bank lending to monetary policy our results are consistent with a demand driven transmission mechanism that works through firm balance sheets and is independent from the bank lending channel

a tale of two shares the relationship between the illegitimacy ratio and the marriage share abstract our model implies a magnified effect of marriage rates on the illegitimacy ratio for u s data plots and regression estimates support the prediction that the share of unmarried births is driven by the square of the share of unmarried women

bank integration and state business cycles we investigate how integration of bank ownership across states has affected economic volatility within states in theory bank integration could cause higher or lower volatility depending on whether credit supply or credit demand shocks predominate in fact year to year fluctuations in a state s economic growth fall as its banks become more integrated via holding companies with banks in other states as the bank linkages between any pair of states increase fluctuations in those two states tend to converge we conclude that interstate banking has made state business cycles smaller but more alike i introduction the united states banking system was once anything but united until 1978 every state in the union barred banks from other states so instead of one national banking system we had more like 50 little banking systems one per state 1 once states opened their borders to out of state banks bank holding companies marched in and bought up or merged with banks all over the country in 1975 just 10 percent of the bank assets in the typical state were owned by a multistate bank holding company by 1994 this interstate bank asset ratio had risen to 60 percent figure i our paper investigates how the advent of interstate banking integration in the united states has affected economic volatility within states with the united states balkanized banking system the fate of a state and its banks were closely tied as went the state so went the banks the farm price deflation in the early 1980s bankrupted many farmers and many farm banks falling oil prices in the mid 1980s wiped out a lot of texans and a lot of texas banks shocks to commodity prices probably caused these contractions but frictions in the banking sector may have aggravated them by allowing a freer flow of bank capital and lending among states we maintain that interstate banking will reduce the drag that banking frictions can have on economic contractions

optimal dynamic pricing for deteriorating items with reference price effects when inventories stimulate demand abstract in this paper we incorporate reference price effects into a deteriorating inventory problem when the demand rate depends on displayed stock level and selling price simultaneously reference price effects are formed empirically by customers to adjust current price perception on the basis of past purchases the market demand is assumed to be responsive to the difference between the current selling price and the reference price which is perceived as a loss or a gain we consider three scenarios of market demand loss neutrality loss aversion and loss seeking an optimal dynamic pricing model is established to determine a pricing strategy maximizing the discounted total profit over an infinite time horizon theoretical results are derived to demonstrate the existence of the optimal solutions and to explore the relationships between optimal pricing decisions and an initial reference price based on mild assumptions numerical example and sensitivity analysis are presented to illustrate the theoretical results and managerial insights finally concluding remarks are offered

a note on eoq models for deteriorating items under stock dependent selling rate abstract in 1995 padmanabhan and vrat presented inventory models for deteriorating items with stock dependent selling rate and derived the profit functions without backlogging and with complete backlogging first this paper develops the necessary and sufficient conditions of the existence and uniqueness of the optimal solutions of the profit per unit time functions without backlogging and with complete backlogging second this paper explains that it is appropriate to use the newton raphson method to find the optimal solutions of the profit functions per unit time in both situations modelled

an eoq model with stock dependent demand shortage inflation and time discounting abstract this paper develops a finite time horizon deterministic economic order quantity eoq inventory model with shortages where the demand rate at any instant depends on the on hand inventory stock level at that instant the effects of inflation and the time value of money are taken into account considering two separate inflation rates namely the internal company inflation rate and the external general economy inflation rate the results are discussed with a numerical example and particular case of the model is discussed in brief a sensitivity analysis of the optimal solution with respect to the parameters of the system is carried out

inventory model with stock level dependent demand rate and variable holding cost inventory models in which the demand rate depends on the inventory level are based on the common real life observation that greater product availability tends to stimulate more sales previous models incorporating inventory level dependent demand rate assume that the holding cost is constant for the entire inventory cycle this paper considers the inventory policy for an item with a stock level dependent demand rate and a storage time dependent holding cost the holding cost per unit of the item per unit time is assumed to be an increasing function of the time spent in storage two time dependent holding cost step functions are considered retroactive holding cost increase and incremental holding cost increase procedures are developed for determining the optimal order quantity and the optimal cycle time for both cost structures

social approval values and afdc a re examination of the illegitimacy debate this paper models the fertility decision of individuals who differ in their wage rate and their intensity of preferences for rearing children and whose utility of having a child out of wedlock depends on the level of social approval associated with doing so this social approval in turn is a function of the fraction of individuals in previous generations that chose to have children out of wedlock the model is a straightforward extension of the typical rational choice model that motivates much of the empirical literature a literature that has cast doubt on a strong link between afdc and illegitimacy however the model introduces elements from epidemic models that many have in mind when arguing for such a link as a result the predictions of this extended model are consistent with empirical findings while at the same time linking the rise in illegitimacy solely to government welfare programs specifically a program similar to afdc is introduced into an economy with low illegitimacy rates and a trans

an order level lot size inventory model with inventory level dependent demand and deterioration abstract many inventory models have been developed for various deteriorating items with constant demand rate it is a common experience that for perishable consumer goods the age of inventory has a negative impact on the demand due to the loss of consumer confidence on such product consumers tend to keep off perishable items which have reached closer to their expiry dates this paper describes an inventory model in which the demand is considered as a composite function consisting of a constant component and a variable component which is proportional to the inventory level in the periods when there is a positive inventory buildup the rate of production is considered finite and the decay rate as exponential the total cost function is composed of four cost components of all phases of the cycle backorder replenishment inventory buildup inventory depletion and shortage this cost function is later reduced to a two variable function using boundary relations to determine iteratively the set of values of the variables that resulted in minimum cost per cycle the optimum lot size and order level were then obtained with relations established previously results are demonstrated for an instance of the model

investigating recent trends in the u s teen birth rate we investigate trends in the u s rate of teen childbearing between 1981 and 2010 focusing specifically on the sizable decline since 1991 we focus on establishing the role of state level demographic changes economic conditions and targeted policies in driving recent aggregate trends we offer three main observations first the recent decline cannot be explained by the changing racial and ethnic composition of teens second the only targeted policies that have had a statistically discernible impact on aggregate teen birth rates are declining welfare benefits and expanded access to family planning services through medicaid but these policies can account for only 12 6 percent of the observed decline since 1991 third higher unemployment rates lead to lower teen birth rates and can account for 16 percent of the decline in teen birth rates since the great recession began

the economic lot sizing problem with perishable items and consumption order preference abstract we consider the economic lot sizing problem with perishable items els pi where each item has a deterministic expiration date although all items in stock are equivalent regardless of procurement or expiration date we allow for an allocation mechanism that defines an order in which the items are allocated to the consumers in particular we consider the following allocation mechanisms first expiration first out fefo last expiration first out lefo first in first out fifo and last in first out lifo we show that the els pi can be solved in polynomial time under all four allocation mechanisms in case of no procurement capacities this result still holds in case of time invariant procurement capacities under the fifo and lefo allocation mechanisms but the problem becomes np hard under the fefo and lifo allocation mechanisms

inventory models with inventory level dependent demand a comprehensive review and unifying theory marketing researchers and practitioners have long recognized the demand of many retail items is proportional to the amount of inventory displayed recently two distinct types of inventory control models reflecting this relationship have appeared in the literature models in which the demand rate of an item is a function of the initial inventory level and those in which it is dependent on the instantaneous inventory level we present a comprehensive overview of this literature and demonstrate the equivalence of the two types of models through the use of a simple periodic review model an alternative approach to sensitivity analysis for inventory models with inventory level dependent demand is also presented

bank size and macroeconomic shock transmission does the credit channel operate through large or small banks in this paper i use u s call report data to construct a larger panel dataset with bank level observations i find that larger banks lending is considerably more sensitive to the strength of their borrowers and their own balance sheets compared to smaller banks and that the sensitivities to borrower balance sheets are larger in magnitude compared to lender balance sheets when i incorporate various macroeconomic shocks identified by an estimated dsge model into the empirical model i similarly find that the transmission of shocks to the real economy operates mostly through large bank lending and borrower balance sheets

an inventory model for deteriorating items with stock dependent demand rate abstract this paper discusses an inventory model with an inventory level dependent demand rate followed by a constant demand rate for items deteriorating at a constant rate where the terminal condition of zero inventory at the end of the scheduling period has been relaxed sensitivity of the decision variables to changes in the parameter values is examined and the effects of these changes on the optimal policy are discussed in brief

a production inventory model in an imperfect production process abstract the paper develops a model to determine the optimal product reliability and production rate that achieves the biggest total integrated profit for an imperfect manufacturing process the basic assumption of the classical economic manufacturing quantity emq model is that all manufacturing items are of perfect quality the assumption is not true in practice most of the production system produces perfect and imperfect quality items in some cases the imperfect quality non conforming items are reworked at a cost to restore its quality to the original one rework cost may be reduced by improvements in product reliability i e decreasing in product reliability parameter lower value of product reliability parameter results in increase development cost of production and also smaller quantity of nonconforming products the unit production cost is a function of product reliability parameter and production rate as a result higher development cost increases unit production cost the problem of optimal planning work and rework processes belongs to the broad field of production inventory model which deals with all kinds of reuse processes in supply chains these processes aim to recover defective product items in such a way that they meet the quality level of good item the benefits from imperfect quality items are regaining the material and value added on defective items and improving the environment protection in this point of view a model is introduced here to guide a firm industry in addressing variable product reliability factor variable unit production cost and dynamic production rate for time varying demand the paper provides an optimal control formulation of the problem and develops necessary and sufficient conditions for optimality of the dynamic variables in this purpose the euler lagrange method is used to obtain optimal solutions for product reliability parameter and dynamic production rate finally numerical examples are given to illustrate the proposed model

an eoq model for perishable items under stock dependent selling rate and time dependent partial backlogging in the present paper we extend padmanabhan and vrat s model by proposing a time proportional backlogging rate to make the theory more applicable in practice the existence and uniqueness of the solutions of the relevant systems are examined subsequently a numerical example is presented to illustrate the application of developed model

treatment effect heterogeneity in theory and practice instrumental variables iv methods identify internally valid causal effects for individuals whose treatment status is manipulable by the instrument at hand inference for other populations requires homogeneity assumptions this paper outlines a theoretical framework that nests causal homogeneity assumptions these ideas are illustrated using sibling sex composition to estimate the effect of childbearing on economic and marital outcomes the application is motivated by american welfare reform the empirical results generally support the notion of reduced labour supply and increased poverty as a consequence of childbearing but evidence on the impact of childbearing on marital stability and welfare use is more tenuous

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

on the sources of business cycles in the g 7 abstract this paper examines sources of cyclical movements in output inflation and the term structure of interest rates in the g 7 it employs a novel identification approach which uses the sign of the theoretical cross correlation function in response to shocks to catalog orthogonal disturbances we find that demand shocks are the dominant source of output and inflation fluctuations in several of the g 7 countries the proportion of term structure variability explained by different structural sources does not depend on the horizon apart from the us and canada structural shocks are nearly uncorrelated across countries

are scale economies in banking elusive or illusive evidence obtained by incorporating capital structure and risk taking into models of bank production abstract this paper explores how to incorporate banks capital structure and risk taking into models of production in doing so the paper bridges the gulf between 1 the banking literature that studies moral hazard effects of bank regulation without considering the underlying microeconomics of production and 2 the literature that uses dual profit and cost functions to study the microeconomics of bank production without explicitly considering how banks production decisions influence their riskiness various production models that differ in how they account for capital structure and in the objectives they impute to bank managers cost minimization versus value maximization are estimated using u s data on highest level bank holding companies modeling the bank s objective as value maximization conveniently incorporates both market priced risk and expected cash flow into managers ranking and choice of production plans estimated scale economies are found to depend critically on how banks capital structure and risk taking are modeled in particular when equity capital in addition to debt is included in the production model and cost is computed from the value maximizing expansion path rather than the cost minimizing path banks are found to have large scale economies that increase with size moreover better diversification is associated with larger scale economies while increased risk taking and inefficient risk taking are associated with smaller scale economies

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

the economic consequences of unwed motherhood using twin births as a natural experiment social scientists have long concluded that premarital childbearing exacerbates problems of both poverty and family instability out of wedlock and adolescent childbearing may reduce a mothers educational attainment lower the probability of her eventual marriage increase her probability of welfare recipiency and decrease family income the authors use an exogenous fertility event the birth of twins to estimate the economic effects of unplanned births the approach compares the economic outcomes of women experiencing premarital twin first births to those experiencing premarital single first births in the attempt to identify the consequences of an unplanned birth upon womens future fertility and marital decisions education labor force participation labor earnings welfare receipt and poverty status 1970 and 1980 us census micro data are used to identify twin births to unmarried women analysis found large short term effects of unplanned births on labor force participation poverty and welfare recipiency among unwed mothers but not among married mothers furthermore most adverse economic effects of unplanned motherhood dissipate over time for whites but larger and more persistent negative effects weigh upon black unwed mothers

a generalization of sensitivity of the inventory model with partial backorders abstract in this paper we use the elementary techniques of differential calculus to investigate the sensitivity analysis of montgomery et al s montgomery d c bazaraa m s keswani a k 1973 inventory models with a mixture of backorders and lost sales naval research logistics quarterly 20 225 263 inventory model with a mixture of backorders and lost sales and generalize chu and chung s chu p chung k j 2004 the sensitivity of the inventory model with partial backorders european journal of operational research 152 289 295 sensitivity analysis we provide three numerical examples to demonstrate our findings and remark the interpretation of the global minimum of the average annual cost at which the complete backordering occurs

financial intermediation and delegated monitoring this paper develops a theory of financial intermediation based on minimizing the cost of monitoring information which is useful for resolving incentive problems between borrowers and lenders it presents a characterization of the costs of providing incentives for delegated monitoring by a financial intermediary diversification within an intermediary serves to reduce these costs even in a risk neutral economy the paper presents some more general analysis of the effect of diversification on resolving incentive problems in the environment assumed in the model debt contracts with costly bankruptcy are shown to be optimal the analysis has implications for the portfolio structure and capital structure of intermediaries

identifying the role of risk shocks in the business cycle using stock price data i introduction the finance literature on the forecastibility of stock returns has concluded that stock market movements are by and large not because of changes in the expected future cash flow of firms but are primarily because of changes in the risk premium that is how the expected cash flows are discounted by stock market participants cochrane 2011 1 these changes in risk premia also have important implications for real variables in the economy especially for consumption and investment an increase in the risk premium prompts households to reduce current consumption as they start to discount expected future income more heavily more importantly changes in the required return on equity alter the cost of capital of corporations when they finance new investment for firms that rely on external debt to finance marginal investment a lower stock price translates into lower net worth and therefore a higher cost of borrowing bernanke gertler and gilchrist 1999 similarly firms that rely on new equity issues are able to raise less funds from each new share when their stock price is lower even for firms that finance investment exclusively through internal funds i e retained earnings plus depreciation allowance the required return on existing shares reveals the opportunity cost of internally financed investment tobin 1969 tobin and brainard 1977 this is because at least in principle these funds can be returned to existing shareholders as dividends and new funds can then be raised from the markets through new equity shares for which investors would demand a risk premium figure 1 omitted in the aggregate u s corporations are predominantly financed through equity the dotted line in figure 1 plots the credit market liabilities of u s non financial corporations as a percent of the sum of equity and credit market liabilities in their balance sheets 2 by this measure debt financing accounts for about a third of total financing averaged over the whole sample and equity financing accounts for about two thirds the solid line in figure 1 provides an alternative measure which takes into account all financial liabilities including items such as trade payables but nets out financial assets to obtain a measure of net debt mcgrattan and prescott 2005 now debt financing accounts for only 15 of total financing in the post war period and its importance has declined in the last two decades note that both of these series are stock measures as opposed to flow measures that is they refer to financing of all past investments and do not necessarily reflect how corporations are financing investment at the margin these measures can also be biased against debt financing because most debt items are recorded on a book value basis in the flow of funds but equity is recorded on a market value basis to overcome these caveats i consider the flow components of sources of funds i e internal funds net new equity and net new debt as a share of corporate tangible investment in figure 2 several patterns emerge first the ratio of internal funds to gross capital expenditures has been close to 1 throughout the post war period in other words at least in the aggregate u s corporate investment has been by and large financed internally second new equity issuance has not been an important source of financing in fact net new stock issues have been mostly negative in the latter part of the sample this mainly reflects the preference of corporations to distribute resources to shareholders through stock buybacks rather than ordinary dividend payments because of the preferential tax treatment of long term capital gains third net new debt has contributed to about a third of aggregate financing assuming that the discrepancy in the flow account is distributed proportionally to each financing component as internal funds and net new stock issues are fairly reliable data series we can reasonably lump the rather large discrepancy item in the ffa data with net debt

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

identifying the balance sheet and the lending channels of monetary transmission a loan level analysis abstract we make a novel attempt at comparing the strength of the lending and balance sheet channels of monetary transmission to make this comparison we use loan level data to determine how borrower balance sheets and bank liquidity are related to bank lending decisions and how monetary policy can affect these relationships the key innovation in this paper is the use of loan level data this enables us to measure the independent effects of the two channels and directly account for borrower balance sheets and lender liquidity instead of using proxies our results show that the balance sheet channel is the main mechanism through which monetary policy shocks are transmitted to the economy and that the lending channel does not play a significant role

sustainable inventory system with controllable non instantaneous deterioration and environmental emission rates abstract in today s environment it is difficult to be successful without considering sustainability the effects of global warming are becoming more observable in daily life supply chain activities are important sources of environmental emissions this effect increases concerns to control emissions through the development of a supply chain inventory model a replenishment problem based on joint pricing dynamic investment in environmental cost order cost preservation technology cost and optimal replenishment times for a non instantaneous deteriorating item is considered as a way to maximize retailer profit in this problem the demand rate depends on the stock and selling price an algorithm is used to find the optimum solution of the supply chain inventory problem which determines the selling price preservation technology investment cost environmental emission cost order cost and replenishment cycle time theoretical analysis of the optimal properties of the proposed model is provided and then solution methods are proposed numerical analysis is conducted to show the application of the model managerial implications are given to practitioner this study demonstrates that the proposed model could be applied under real world situations

deregulation and bank financial policy the standard view that banks can value maximize by exploiting non risk rated deposit insurance ignores the potential loss of a valuable bank charter due to insolvency recognition of this effect changes the bank s optimal financial policy and can induce extreme risk averting as well as risk taking behavior however as the value of the bank charter falls the risk taking strategy is more apt to dominate therefore current deregulation of the banking industry by easing entry and devaluing charters holds the potential for increases in the incidence of insolvency unless offsetting policies are instituted

production inventory models for a damageable item with variable demands and inventory costs in an imperfect production process in this paper economic production quantity epq models for breakable or deteriorating item are developed with variable demands being dependent on time or on hand stock here rate of production and holding cost are time dependent unit production cost is a function of both production reliability indicator and production rate set up cost is also partially production rate dependent the production process produces some imperfect quantities which are instantly reworked at a cost to bring back those units to the perfect ones the production process ultimately depends on both time and reliability indicator the models are formulated as optimal control problems and the total profit functions with effect of inflation and time value of money are expressed as finite integrals over the finite planning horizon the problems are solved using euler lagrange function based on variational calculus and newton raphson method to determine the optimal production reliability indicator r and then corresponding production rates and total profits in some cases results of the models for deteriorating item are obtained as particular cases from those of breakable item models similarly results of simple epq models without damageability are deduced as particular cases numerical experiments are performed to illustrate the models both numerically and graphically

optimal replenishment policies for non instantaneous deteriorating items with stock dependent demand abstract wu et al 2006 an optimal replenishment policy for non instantaneous deteriorating items with stock dependent demand and partial backlogging international journal of production economics 101 369 384 established an inventory model for non instantaneous deteriorating items with stock dependent demand and obtained the optimal replenishment policy in this paper we first amend wu et al s model by changing the objective to maximizing the total profit secondly we set a maximum inventory level in the model to reflect the facts that most retail outlets have limited shelf space thirdly we relax the restriction of zero ending inventory when shortages are not desirable we then establish the theoretical results and provide an algorithm to find the optimal solution finally we present some numerical examples to illustrate the results

deterministic models of perishable inventory with stock dependent demand rate and nonlinear holding cost this paper deals with an extended eoq type inventory model for a perishable product where the demand rate is a function of the on hand inventory the traditional parameters of unit item cost and ordering cost are kept constant but the holding cost is treated as i a nonlinear function of the length of time for which the item is held in stock and ii a functional form of the amount of the on hand inventory the approximate optimal solution in both the cases are derived computational results are presented indicating the effects of nonlinearity in holding costs

an optimal replenishment policy for non instantaneous deteriorating items with stock dependent demand and partial backlogging abstract in this study we consider a problem of determining the optimal replenishment policy for non instantaneous deteriorating items with stock dependent demand in the model shortages are allowed and the backlogging rate is variable and dependent on the waiting time for the next replenishment the necessary and sufficient conditions of the existence and uniqueness of the optimal solution are shown as the special cases the results for the models with instantaneous or non instantaneous deterioration rate and with or without shortages are derived further we analytically identify the best circumstance among these special cases based on the minimum total relevant cost per unit time sensitivity analysis of the optimal solution with respect to major parameters is carried out finally four numerical examples are presented to demonstrate the developed model and the solution procedure

a returns policy for distribution channel coordination of perishable items abstract this paper deals with a retailer s operating policies for a perishable product when he agrees with his supplier not to return the unsold product to his supplier provided that the supplier gives some discount on the wholesale price mathematical formulations are developed based on a periodic review inventory model under lifo and fifo issuing policies the demand rate is assumed to be a function of the retail price and instantaneous inventory level decision variables are the amount of supplier s price discount that the retailer can accept in return for adopting the no returns condition the retail price and order size also numerical examples are solved with tabu search algorithm for sensitivity analysis

an eoq model for perishable product with special sale and shortage abstract in this paper for the first time an inventory control model to determine the optimal order and shortage quantities of a perishable item when the supplier offers a special sale is developed four possible cases based on decision that the purchaser might make about the first replenishment policy using regular economic order quantity model at reduced price or regular price if he did not take the special order and coincidence of special period length with positive or negative inventory level of the last regular period length during the special period are investigated moreover several useful theorems are suggested through which one can find closed form solution directly when there are integer operators involved in an objective function at the end in order to illustrate the proposed theorems and the solution method some numerical examples are solved and a sensitivity analysis is reported too

how did bank holding companies prosper in the 1990s abstract this paper examines the improved performance of us bank holding companies bhcs from 1991 to 1997 analysis of cost and profit functions using several alternative output specifications suggests that the gains were primarily due to productivity growth and changes in scale economies various econometric methodologies yield productivity growth of about 0 4 per year and the optimal size seems to have increased in the 1990s era of deregulation technological change and financial innovation estimates of both productivity growth and economies of scale are robust across traditional and non traditional output specifications despite the overall success however substantial cost and profit inefficiency existed for bhcs of all sizes in the 1990s these efficiency estimates are particularly sensitive to the output specification and failure to account for non traditional activities like off balance sheet obs items leads profit efficiency but not cost efficiency to be understated for the largest bhcs

perishable inventory management subject to stochastic leadtime abstract this paper discusses the model for a perishable product with the stochastic procurement leadtime zero or 1 unit leadtime is considered and its optimal ordering policy is derived this is a generalization of the one period horizon model of nahmias 4 further the chance constraint as for shortage is added and under this additional constraint again optimal ordering policy is obtained

an optimal production inventory model for deteriorating items with multiple market demand the global markets of today offer more selling opportunities to the deteriorating items manufacturers but also pose new challenges in production and inventory planning from a production management standpoint opportunities to exploit the difference in the timing of the selling season between geographically dispersed markets for deteriorating items are important to improving a firm s profitability in this paper we examined the above issue with an insightful production inventory model of a deteriorating items manufacturer selling goods to multiple markets with different selling seasons we also provided a solution procedure to find the optimal replenishment schedule for raw materials and the optimal production plan for finished products a numerical example was then used to illustrate the model and the solution procedure finally sensitivity analysis of the optimal solution with respect to major parameters was carried out

eoq models for perishable items under stock dependent selling rate this paper presents inventory models for perishable items with stock dependent selling rate the selling rate is assumed to be a function of current inventory level and rate of deterioration is taken to be constant under instantaneous replenishment with zero lead time the model incorporates aspects such as complete partial and no backlogging eoq is determined for maximizing the total profit in each of the situations the models developed are illustrated through numerical examples and sensitivity analysis is reported

economic order quantity models with nonlinear holding costs abstract we consider a generalization of the classical economic order quantity model the traditional parameters of unit cost selling price demand rate and set up cost are constant but the holding cost per unit is a non linear function of the length of time the item is held in stock the application is to any inventory system where the value of the item decreases non linearily the longer it is held in stock for the case of deterministic demands we present the cost formula and the optimal order quantity for both finite and infinite horizons for the case of stochastic demands the cost function is examined and the optimal order amount is presented computational results are presented indicating the effect of the non linearity in holding costs

did expanding the eitc promote motherhood during the 1990 s the earned income tax credit eitc emerged as a primary means of providing income support for low income families in the united states in an effort to keep the program well targeted the credit largely restricts eligibility to tax filers with children one potentially unintended consequence of this design is that it might encourage childbearing we raise the question of whether the eitc through its generous benefits to families with children actually increases fertility we approach this topic for three reasons the first is to expand upon an existing literature of economic incentives and fertility using the eitc expansion as a large exogenous variation in the price of childbearing findings in the welfare literature are inconclusive robert a moffitt 1998 and the income tax literature typically finds small but statistically significant effects of the income tax system on fertility behavior e g leslie a whittington et al 1990 second declining fertility rates in many western counties raise the general issue of whether the tax system can be used as a tool for encouraging fertility finally by considering the link between the eitc and fertility we question a common yet untested assumption in the literature on the eitc and the labor supply of single parents that the presence of a child is exogenous to the value of the eitc

an eoq model with state dependent demand rate we present an eoq type model in which the demand rate is a function of the inventory level the demand functions and holding cost functions considered are quite general in particular we focus on two types of demand rate functions a piecewise constant function and a family of exponential functions the paper includes analysis of the problem optimization and sensitivity analysis we also extend the model by adding randomness to the order sizes

the effect of welfare payments on the marriage and fertility behavior of unwed mothers results from a twins experiment we study the relationship between welfare benefits and the time to first marriage and time to next birth among initially unwed mothers we use twin births to generate random within state variation in benefits effectively controlling for unobservables that may confound the relationship between welfare payments and behavior higher base welfare benefits 1 lead unwed white mothers to forestall their eventual marriage and 2 lead unwed black mothers to hasten their next birth the magnitudes of these effects are fairly modest moreover we find no evidence that the marginal benefit paid at the birth of an additional child the focus of the family cap debate affects fertility

an optimal procurement policy for items with an inventory level dependent demand rate and fixed lifetime abstract this paper investigates an optimal procurement policy for items with an inventory level dependent demand rate and fixed lifetime the demand rate is assumed to be a function of current inventory level and each unit has its fixed expiry date so any units which remain unused by their expiry date are considered outdated and must be disposed of for the system presented a mathematical model and solution methodology were developed sensitivity of the decision variables to changes in the parameter values is examined and future research needs are discussed in brief

a two echelon inventory distribution system with power demand pattern and backorders abstract this paper addresses the implications of considering power demand pattern and backorders in the one warehouse n retailer problem specifically we assume that items at the retailers are withdrawn from the inventory following a power pattern the objective function consists of the sum of ordering holding and backordering costs at all installations this objective function depends on the class of inventory policies that we choose for the formulation of the problem in general obtaining the cost function is an arduous task since the average inventory at the warehouse could be difficult to determine however if we apply single cycle policies the computation of the total average cost becomes possible under these assumptions we show that the one warehouse n retailer system with power demand pattern and backorders can be formulated as a mixed non linear programming problem

eoq models with general demand and holding cost functions abstract we consider the continuous deterministic infinite horizon single item inventory system within the setting of a retail sector in which the demand rate for an item is dependent on the existing inventory level the traditional parameter of the replenishment cost is kept constant but the carrying cost per unit is allowed to vary two possibilities of variation are considered a a non linear function of the length of time the item is held in inventory and b a non linear function of the amount of on hand inventory we find the optimal policies and decision rules and show that the classical eoq model is obtained as a limiting case

mortgage modification and strategic behavior evidence from a legal settlement with countrywide abstract we investigate whether homeowners respond strategically to news of mortgage modification programs we exploit plausibly exogenous variation in modification policy induced by settlement of us state government lawsuits against countrywide financial corporation which agreed to offer modifications to seriously delinquent borrowers using a difference in differences framework we find that countrywide s monthly delinquency rate increased more than 0 54 percentage points a 10 percent relative increase immediately after the settlement s announcement the estimated increase in default rates is largest among borrowers least likely to default otherwise these results suggest that strategic behavior should be an important consideration in designing mortgage modification programs jel d14 g21 k22 r31

marriage divorce and social safety net policy i study the effects of the earned income tax credit eitc and welfare reforms of the 1990s on flows into and out of marriage i use test scores to predict who is most likely to be affected by the policy changes and employ a flexible functional form to estimate heterogeneous effects i find that lower earning married women are more likely to divorce as the eitc expands but i find no effect of eitc generosity on marriage i find little effect of welfare generosity on marriage or divorce flows for any group my results suggest that there are nonsymmetric responses to policy on flows into and out of marriages

optimal inventory policy for a perishable item with demand function sensitive to price and time abstract we formulate a model for determining the optimal pricing order quantity and replenishment period for perishable items with price dependent and time dependent demand the items have a fixed shelf life and the demand rate decreases linearly in the selling price and polynomially over the time after replenishment until it vanishes either at the reservation price or at expiration time we prove that the three variable profit maximization problem can be reduced into a single variable problem in which the variable is the duration of the replenishment period we show that the profit function is strictly pseudo concave and provide means of obtaining the optimal policy three numerical examples are presented to demonstrate the model accompanied by a sensitivity analysis

s 1 s policies for perishable inventory we consider s 1 s policies for a single item whose lifetime is fixed and known with certainty demands are generated by a stationary poisson process and there is a positive leadtime for replenishment we believe this study gives the only analysis for perishables with a positive order leadtime the analysis involves the derivation of the stationary distribution of the s dimensional stochastic process corresponding to the time elapsed since the last s orders were placed this distribution is then used to obtain an expression for the expected cost rate of operating the system in steady state as a function of s a computer program has been developed to compute optimal s values and expected annual costs we report a computation for a variety of system parameters which show some of the unusual features of the problem finally we show how this model can be used in the context of a problem of optimizing availability of operating equipment subject to scheduled maintenance as well as random failure

the married widow marriage penalties matter marriage penalties are a controversial feature of many government policies empirical evidence of their behavioral effects is quite mixed which is surprising because economic theory predicts that they should have an impact on the headship decision we investigate the removal of marriage penalties from the surviving spouse pensions of the canadian public pension system in the 1980s these reforms provide a simple and transparent source of identification our results indicate that marriage penalties can have large and persistent effects on marriage decisions we also present evidence suggesting that it is individuals with characteristics correlated with greater wealth who respond to the penalties jel j1 h2

efficiency technical change and returns to scale in large us banks panel data evidence from an output distance function satisfying theoretical regularity abstract this paper provides parametric estimates of technical change efficiency change economies of scale and total factor productivity growth for large banks those with assets in excess of 1 billion in the united states over the period from 2000 to 2005 this is done by estimating an output distance function subject to theoretical regularity within a bayesian framework we find that failure to incorporate theoretical regularity conditions results in mismeasured shadow revenue and or cost shares which in turn leads to perverse conclusions regarding productivity growth our results from the regularity constrained model show that total factor productivity of the large us banks grew at an average rate of 1 98 over the sample period however our estimates also show a clear downward trend in the growth rate of total factor productivity and our decomposition of the primal divisia total factor productivity growth index into its three components technical change efficiency change and economies of scale indicates that technical change is the driving force behind this decline

the impact of welfare on young mothers subsequent childbearing decisions the impact of welfare on fertility in the united states is explored focusing on the theory that some women have many children to increase their incomes and to prolong their stay on welfare rolls the author examines the relationship between welfare and births to women who already have a child using data on young mothers from the national longitudinal survey of youth nlsy i find that variations in welfare benefit levels and the incremental benefit have no statistically significant impacts on the subsequent childbearing decisions of young mothers in general nor on the subsequent childbearing decisions of women who received welfare in particular furthermore mothers who received welfare to support their first children are no more likely to have additional children in any given year through the age of 23 excerpt

optimal dynamic pricing and replenishment cycle for non instantaneous deterioration items with inventory level dependent demand abstract this paper considers a problem of determining the optimal dynamic pricing strategy and replenishment cycle for non instantaneous deteriorating items where the consumer demand depends on the sales price and the quantity of the items displayed in the store for the given replenishment cycle we derive the optimal dynamic pricing strategy by applying pontryagin s maximum principle and then design an effective algorithm to obtain the optimal dynamic pricing strategy and replenishment cycle simultaneously numerical examples are provided to illustrate the effectiveness of the proposed methods and solution procedure furthermore sensitivity analysis of the key system parameters is carried out and some interesting managerial insights are presented

supply chain coordination contracts with inventory level and retail price dependent demand abstract in this paper three unlike coordinating contracts namely i joint rebate contract ii wholesale price discount contract and iii cost sharing contract are proposed for two echelon supply chain coordination perspective under stock and price induced demand it is found analytically that the manufacturer s and the retailer s preferences among three contractual forms are not always aligned by applying bargaining theory it is established that stock elasticity plays an important role to select coordination contract and a threshold value stock elasticity is also determined below which cost sharing contract is not feasible it is also found that the retailer with higher bargaining power always prefers wholesale price discount contract among considered three contracts results are illustrated analytically as well as numerically