optimal pricing and lot sizing under conditions of perishability finite production and partial backordering and lost sale abstract perishable products constitute a sizable component of inventories common questions in a production and selling situation involving a perishable or a non perishable product are what should be the price and what should be the size of the replenishment when demand for the product is price sensitive pricing and lot sizing decisions are interdependent similarly when a product is highly perishable the demand may need to be backlogged to avoid costs due to deterioration i e perishability and backlogging are complementary conditions in this paper we consider the pricing and lot sizing problem for a perishable good under finite production exponential decay and partial backordering and lost sale the backlogging phenomenon in the literature is often modeled using backordering and lost sale costs these cost parameters however are not easy to estimate in practice in this paper we use a new approach to model backlogging of demand in this approach customers are viewed to be impatient the backlogging option gets used only when it is economic to do so we extend the analysis presented for a perishable product to the case in which the product is non perishable

analysis of an inventory system with exponential partial backordering abstract in this paper we study an inventory model with partial backlogging where unsatisfied demand is partially backlogged according to an exponential function in this model the total cost is the sum of the order cost the holding cost the backorder cost which includes a fixed cost and a cost proportional to the length of time for which the backorder exists and the cost of lost sales a general approach for finding the optimal policy is developed numerical examples are used to illustrate how the approach works

impact of modern agricultural technologies on smallholder welfare evidence from tanzania and ethiopia this paper evaluates the potential impact of adoption of improved legume technologies on rural household welfare measured by consumption expenditure in rural ethiopia and tanzania the study utilizes cross sectional farm household level data collected in 2008 from a randomly selected sample of 1313 households 700 in ethiopia and 613 in tanzania the causal impact of technology adoption is estimated by utilizing endogenous switching regression this helps us estimate the true welfare effect of technology adoption by controlling for the role of selection problem on production and adoption decisions our analysis reveals that adoption of improved agricultural technologies has a significant positive impact consumption expenditure in per adult equivalent terms in rural ethiopia and tanzania this confirms the potential role of technology adoption in improving rural household welfare as higher consumption expenditure from improved technologies translate into lower poverty higher food security and greater ability to withstand risk an analysis of the determinants of adoption highlighted inadequate local supply of seed access to information and perception about the new cultivars as key constraints for technology adoption

technology adoption under seed access constraints and the economic impacts of improved pigeonpea varieties in tanzania dry land legumes well adapted to drought prone areas have largely been neglected in the past despite the good opportunities they offer for income growth and food and nutritional security for the poor this study evaluated the adoption and impact of two farmer and market preferred and disease resistant pigeonpea varieties that were developed and promoted in semi arid tanzania the new varieties were resistant to fusarium wilt a fungal disease devastating the crop however farmers wanting to adopt new varieties did not adopt due to seed access constraints and under developed seed delivery systems adoption of new varieties is therefore analyzed using an augmented double hurdle model that allows estimating variety adoption conditional on seed access thresholds accounting for the additional information on sample separation the study identifies the crucial role of seed access local supply extension education participatory decision making capital and household assets in determining adoption the social economic benefits of the technology and policies for improved seed access were further analyzed using the extended economic surplus method dream model even under restrictive assumptions overall discounted benefits were found to be quite attractive indicating the need for additional efforts to scale up the success story analysis of changes in research benefits from relaxing the seed access constraint showed that net gains would increase by up to 30 if farmer access to improved seeds can be assured smallholder farmers are the major beneficiaries along with consumers and rural net buyers who gain from productivity induced lower market prices

world poverty and the role of agricultural technology direct and indirect effects agricultural technology can help reduce poverty through direct and indirect effects direct effects are gains for the adopters while indirect effects are gains derived from adoption by others leading to lower food prices employment creation and growth linkage effects conceptualising and measuring these effects is highly complex yet is needed for each region if technology is to be used as an effective instrument for poverty reduction we propose a methodology for doing this in the context of computable general equilibrium modelling and apply it to archetype models for africa asia and latin america results show that the dominant effect of technology on poverty is through direct effects in africa indirect agricultural employment effects in asia and linkage effects through the rest of the economy in latin america in each case increasing the poverty reduction effect through the targeting of technology across crops and through complementary rural development programmes is also explored

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

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

deteriorating inventory model with quantity discount pricing and partial backordering inventory models with quantity discount pricing and partial backordering although common in practice have received very little attention from researchers the objective of this study is to develop a deterministic inventory model with quantity discount pricing and partial backordering when the product in stock deteriorates with time most retailers make pricing decisions of their products at certain times of the year and these decisions affect demand in this study the demand rate is assumed to decrease as price for the product increases unlike traditional inventory models that seek to minimize cost the objective of this study is to maximize profit the findings of this study are particularly relevant to retailers of deteriorating products in a competitive environment a numerical example is given to illustrate the theory

adoption of agricultural innovations in developing countries a survey this paper reviews various studies which have provided a description and possible explanation to patterns of innovation adoption in the agricultural sector the survey points out that the tendency of many studies to consider innovation adoption in dichotomous terms adoption nonadoption may not be appropriate in many cases where the actual decisions are defined over a more continuous range more attention needs to be given to the socio cultural and institutional environment in area studies so that their interrelation with economic factors affecting adoption can be inferred the presence of several interrelated innovations is another aspect that needs to be considered more carefully in future research since a number of simultaneous decisions may be involved furthermore the possibility of regular sequential patterns in adopting components of a new technological package should be specifically addressed in future studies finally the impact of differential adoption rates on land holding distribution merits attention in future research

the productivity and income effects of adoption of improved soybean varieties and agronomic practices in malawi abstract soybean constitutes an important component of the maize based smallholder cropping systems in malawi and holds considerable potential for countering soil fertility decline enhancing household food and nutrition security and raising rural incomes a number of yield enhancing improved soybean varieties and agronomic practices isvaps have been developed and disseminated in malawi but there is limited evidence on the adoption and impacts of these technologies this paper assesses the productivity and income effects of adopting isvaps using plot level data collected from a nationally representative sample of 1237 soybean growing households in malawi our results show that over a third of the sampled households have adopted isvaps furthermore results from a stochastic dominance analysis showed that soybean yields and net crop incomes for adopters are significantly higher than those of non adopters over the entire probability distribution of isvaps adoption endogenous switching regression model results further demonstrated that adoption of isvaps is associated with an average of 61 yield gain and 53 income gain for adopters overall the results point to the need for further scaling of isvaps for greater adoption and impact on the livelihoods of smallholder farmers in malawi

the deterministic eoq with partial backordering a new approach previous authors have shown that if demand that cannot be filled from stock is partially backordered then using the full backordering model or assuming that all stockouts will result in lost sales can lead to substantial increases in cost relative to using a model that specifically recognizes the percentage of the stockouts that will be backordered the models that these authors developed resulted in procedures or equations that are relatively difficult to use in this paper we take a different approach to modeling the deterministic eoq with partial backordering that results in equations that are more like the comparable equations for the basic eoq and its full backordering extension

impact of conservation agriculture technology on household welfare in zambia this article examines the determinants and impact of conservation agriculture ca technology adoption on farm household welfare in zambia to account for selection bias from both observable and unobservable factors an endogenous switching regression model is employed to estimate the impact of the technology on continuous outcomes like farm output throughput accounting ratio tar poverty gap and severity of poverty a recursive bivariate probit model is however used for the estimation of impact of adoption on a binary outcome like poverty headcount the empirical findings demonstrate that the adoption of ca technology increases maize output and farm tar and reduces household poverty moreover the results reveal that farmers years of schooling social networks access to credit extension services and machinery as well as soil quality positively influence adoption of ca technology

agricultural technology adoption and poverty reduction a propensity score matching analysis for rural bangladesh this study aims at shedding some light on the potential impact of agricultural technology adoption on poverty alleviation strategies it does so through an empirical investigation of the relationship between technological change of the green revolution type and wellbeing of smallholder farm households in two rural bangladeshi regions as technology adoption is not randomly assigned but there is self selection into treatment the paper tackles a methodological issue in assessing the causal effect of technology on farm household wellbeing through the non parametric p score matching analysis it pursues a targeted evaluation of whether adopting a modern seed technology causes resource poor farmers to improve their income and decrease the propensity to fall below the poverty line it finds a robust and positive effect of agricultural technology adoption on farm household wellbeing suggesting that there is a large scope for enhancing the role of agricultural technology in directly contributing to poverty alleviation 2006 elsevier ltd all rights reserved

peasant household behaviour with missing markets some paradoxes explained a model of peasant household behavior under varying degrees of household specific food and labor market failures is constructed to show that these structural features can explain several well known patterns of peasant response which have often been attributed to peculiar motives presumed specific to peasants the model explains sluggish response to cash crops prices and high instability in perceived food and labor scarcities the key role of manufactured consumer goods prices in stimulating peasants effort in cash crops production the effectiveness of taxation as opposed to incentives in stimulating cash crops production and the key role of technological change in food production to enhance cash crop production results are obtained analytically in the case of one market failure and by numerical simulation with more than one

distance based agglomeration externalities and neighbouring firms characteristics abstractthis paper tests the hypothesis that firms with different characteristics can differ in their capability to produce local externalities by investigating the relationship between firm specific distance based weighted agglomeration measures and firms short run productivity growth in the italian manufacturing industry the results suggest that positive localization economies increase with distance when neighbouring firms characteristics are accounted for diversification type forces have negative effects on productivity growth at short distances while there are positive effects at longer distances regardless of the weighting scheme considered moreover the negative effect of inter industry externalities seems to persist over distance when neighbouring firms characteristics are accounted for

an inventory model with deteriorating items quantity discount pricing and time dependent partial backlogging abstract wee international journal of production economics 59 1999 511 in his interesting paper presented a deterministic inventory model with the following characteristics quantity discount schemes for the unit cost partial backlogging at a fixed rate deterioration of stock in time and demand rate being a linear function of the selling price in this article we generalize the work of wee 1999 more specifically we consider a model where the demand rate is a convex decreasing function of the selling price and the backlogging rate is a time dependent function which ensures that the rate of backlogged demand increases as the waiting time to the following replenishment point decreases

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

welfare impacts of maize pigeonpea intensification in tanzania this article examines the driving forces behind farmers decisions to adopt improved pigeonpea and maize and estimates the causal impact of technology adoption on household welfare using data obtained from a random cross section sample of 613 small scale farmers in tanzania we use seemingly unrelated and recursive bivariate probit regressions to test the endogeneity and joint decision making of pigeonpea maize production a double hurdle model is used to analyze the determinants of the intensity of technology adoption conditional on overcoming seed access constraints to address the impact of adoption on welfare the article employs both propensity score matching and switching regression techniques results from bivariate probit models show that unobservable factors cause both decisions to be correlated but the finding does not support the conjecture that both decisions are made jointly overall the analysis of the determinants of adoption identifies inadequate local supply of seed access to information human capital and access to private productive asset as key constraints for pigeonpea technology adoption the causal impact estimation from both the propensity score matching and switching regression suggests that maize pigeonpea adoption has a positive and significant impact on income and consumption expenditure among sample households

adoption of modern varieties farmers welfare and crop biodiversity evidence from uganda abstract this paper assesses the impact of modern varieties adoption on farmers welfare and crop biodiversity conserved in situ using nationally representative data collected in 2009 2010 in uganda an endogenous switching regression model estimates the net economic and environmental effects of switching from local landraces to modern species results show that after controlling for market and agro ecological factors the local varieties perform better than modern ones in marginalized and climatic vulnerable areas crop biodiversity shows to play a fundamental role in farmers risk minimizing strategies when the available modern varieties are not adaptable to the local context and not supported by the required level of agro intensification rural development policies should consider the heterogeneity in the adoption returns and support diversity conservation as a national strategic asset for a suitable bioprospecting and a best fitting agricultural system implementation

a comparison between two pricing and lot sizing models with partial backlogging and deteriorated items abstract recently abad 2003 optimal pricing and lot sizing under conditions of perishability finite production and partial backordering and lost sale european journal of operational research 144 677 685 studied the pricing and lot sizing problem for a perishable good under finite production exponential decay partial backordering and lost sale in this article we extend his model by adding not only the backlogging cost but also the cost of lost goodwill we then analytically compare the net profits per unit time between abad s 2003 model and goyal and giri s 2003 the production inventory problem of a product with time varying demand production and deterioration rates european journal of operational research 147 549 557 model in abad s model the cycle starts with an instant production to accumulate stocks then stops production to use up stocks and finally restarts production to meet the unsatisfied demands by contrast in goyal and giri s model the cycle begins with a period of shortages then starts production until accumulated inventory reaches certain level and finally stops production and uses up inventory our theoretical results show that there is no dominant one between these two models furthermore we provide certain conditions under which one model has more net profit per unit time than the other finally we give several numerical examples to illustrate the results

an integrated production inventory model with imperfect production processes and weibull distribution deterioration under inflation abstract this study develops an integrated production and inventory model from the perspectives of both the manufacturer and the retailer the model assumes a varying rate of deterioration partial backordering inflation imperfect production processes and multiple deliveries the elapsed time until the production process shift is assumed to be arbitrarily distributed the discounted cash flow and classical optimization technique are used to derive the optimal solution a numerical example including the sensitivity analysis is given to validate the results of the production inventory model the integrated decision results in lower optimal joint cost compared with an independent decision by the manufacturer and the retailer

determinants of farmers indigenous soil and water conservation investments in semi arid india abstract this paper investigates the determinants of farmers indigenous soil and water conservation investments in the semi arid tropics of india a simple theoretical model is used to develop hypotheses about the determinants of investment under alternative factor market conditions and these are tested using data on conservation investment from three villages we find that conservation investment is significantly lower on leased land in two of the study villages and lower on plots that are subject to sales restrictions in one village suggesting the potential for land market reforms to increase conservation investment in one village households with more adult males more farm servants and less land invest more in conservation as predicted by the model of imperfect labor markets and households with more debt and off farm income invest more consistent with the model of imperfect credit markets evidence that conservation investment is affected by factor market imperfections is weaker in the other villages where investments are much larger suggesting transaction costs as the source of the differences between villages other factors that have a significant effect on investment include the farmer s education and caste characteristics of the plot size slope irrigation status and quality ranking and the presence of existing land investments the results suggest the importance of accounting for differences across communities and households in factor market and agroclimatic conditions in designing programs to promote investments in soil and water conservation

joint pricing and replenishment policy for deteriorating inventory with declining market abstract this study deals with a deteriorating inventory model where demand decreases linearly with time and cost of items planning horizon is assumed to be finite the replenishment cycles are constant and shortages are partially back ordered the net profit maximizing ordering policy and price are determined for different degree of partial back ordering the reduction in revenue resulted from lost sale is expressed in the lost sale shortage penalty in the total cost formulation a solution method based on nonlinear programming code and the hessian matrix guarantees global optimality of the solution a numerical example is provided to illustrate the theory

estimation of limited dependent variable models with dummy endogenous regressors applied economists have long struggled with the question of how to accommodate binary endogenous regressors in models with binary and nonnegative outcomes i argue here that much of the difculty with limited dependent variables comes from a focus on structural parameters such as index coefcients instead of causal effects once the object of estimation is taken to be the causal effect of treatment several simple strategies are available these include conventional two stage least squares multiplicative models for conditional means linear approximation of nonlinear causal models models for distribution effects and quantile regression with an endogenous binary regressor the estimation strategies discussed in the article are illustrated by using multiple births to estimate the effect of childbearing on employment status and hours of work

demand for improved fish feed in the presence of a subsidy a double hurdle application in kenya fish farming households demand for improved fish feed from the private market in kenya is potentially influenced by the government s feed subsidy program this article applies the double hurdle model to a cross section of fish farms to analyze demand for improved fish feed from private markets and whether the government feed subsidy program has an effect on private demand for improved feed the results indicate that households decisions to participate in the improved feed market are affected by the quantity of improved feed received from the government once the participation decision has been made we find evidence of crowding in of the private improved feed sector that is the government s allocations of subsidized feed appear to increase private sector demand in addition the price of improved feed negatively affects the quantity purchased as expected education extension contacts and ease of marketing matured fish increase household propensity to purchase improved feed commercially policies that help reduce the price of improved feed such as reduction in tariffs on imported feeds and feed ingredients will foster demand for the feed as will policies that facilitate marketing of fish at reasonable prices by households

resource saving and productivity enhancing impacts of crop management innovation packages in ethiopia crop management innovations are often not discrete fixed stand alone options and their adoption may imply various combinations and adaptations this potentially confounds their impact assessment this article assesses the resource saving and productivity enhancing impacts of a crop management package revolving around minimum tillage in maize based farming systems in northwest ethiopia an endogenous switching regression model was applied to plot and household level survey data collected from 290 rural households operating 590 maize plots during the 2012 production year controlling for variations in plot and household characteristics the average effect of minimum tillage package minimum tillage package on maize productivity is 0 44 t ha compared to conventional practice cp adoption of the mtp decreased the average male and female labor use in maize production by 14 4 and 8 2 person days per ha respectively similarly mtp adoption decreased draft power use for land preparation by 13 2 pair of oxen days per ha compared to cp in general there is a considerable short run maize productivity gain and reduction in labor and draft power use under mtp

nonfarm employment agricultural intensification and productivity change empirical findings from uganda this article uses panel data from the living standards measurement study integrated surveys on agriculture for uganda to assess the farm level effects of nonfarm employment on agricultural intensification and productivity change a sample selection model is used to account for both unobserved heterogeneity and potential simultaneity between agricultural production and nonfarm income results show that nonfarm employment can have differential impacts on farm technology intensity and productivity nonfarm income is found to have a positive impact on farm hired labor and improved seed intensity a negative effect on on farm family labor use and no significant impact on fertilizer soil water management and joint use of farm technologies the econometric evidence also indicates that agricultural productivity declines as nonfarm income increases taken together our findings reveal important trade offs between nonfarm employment and income and farm productivity growth under smallholder agriculture the results indicated that targeted policies are required to reduce these potential trade offs between nonfarm employment and agricultural intensification and productivity change

an inventory model for perishable items in a lot size system with quantity discounts abstract an inventory model continuous in units and time is developed for perishable items in a lot size system that allows partially backlogging and partially lost saling the model is developed under deterministic demand instantaneous delivery with quantity discounts and any well behaved probability distribution for the time to perishables an example is given to illustrate the model

optimal policy for an inventory system with backlogging and all units discounts application to the composite lot size model this paper examines an inventory model with full backlogging and all units quantity discounts the practical scenario of a salesperson offering compensation to a client so as not to lose the sale is considered the cost of a backorder thus includes both a fixed cost and a further cost which is proportional to the length of time the said backorder exists a first algorithm is developed to determine the optimal policy while some extensions to this algorithm are obtained that include additional conditions on the model in particular the well known composite lot size model developed by tersine is solved incorporating a new stockout cost and a new all units discount numerical examples are provided to illustrate the application of the algorithms

the adoption and impact of soil and water conservation technology an endogenous switching regression application this paper identifies the factors that affect farmers decisions to adopt soil and water conservation technology in africa and how this technology impacts farm yields and net returns this technology is important because it improves efficiency of water use from rainfall a critical issue in water deficient sub saharan africa an analysis of new data from a survey of 342 rice farmers in northern ghana shows that farmers education capital and labor constraints social networks and extension contacts and farm soil conditions mainly determine adoption of field ridging and the adoption of this technology increases rice yields and net returns significantly jel q15 q24

a survey of deterministic models for the eoq and epq with partial backordering models for the basic deterministic eoq or epq problem with partial backordering or backlogging make all the assumptions of the classic eoq or epq model with full backordering except that only a fraction of the demand during the stockout period is backordered in this survey we review deterministic models that have been developed over the past 40 years that address the basic models and extensions that add other considerations such as pricing perishable or deteriorating inventory time varying or stock dependent demand quantity discounts or multiple warehouses

organic certification agro ecological practices and return on investment evidence from pineapple producers in ghana the recent empirical literature on economic sustainability of certified export crops shows that certification standards that enhance yields are important for improving farm revenues and household welfare however limited evidence exists on the impact of organic certification on the adoption of agro ecological practices in this study we use unique farm level data from pineapple producers in ghana to examine the impact of organic certification on the use of agro ecological practices such as organic fertilizers organic pest and weed control crop rotation and soil and water conservation as well as how using these measures affect farm outcomes such as return on investment our empirical results reveal that organic certification increases agro ecological practice use although from a very low starting point using a generalized propensity score approach we show that there is a positive but nonlinear relationship between the intensity of agro ecological practice use and return on investment