In this thesis, we study the statistical issues in lost sales inventory systems, focusing on the complexity arising from the stochastic demand. We model the demand by the Zero Inflated Poisson (ZIP) distribution. The maximum likelihood estimator of the ZIP parameters taking censoring into account are derived separately for the newsvendor and the (s, S) inventory systems. We also investigate the effect of the estimation errors on the optimal policies and their costs. We observe from a simulation study that the MLE taking censoring into account performed the best in terms of cost as well as policy among various estimates. We then proceed to develop a Bayesian dynamic updating scheme of the ZIP parameters. It is applied to the newsvendor system. We perform a simulation study to investigate the advantage of the Bayesian updating approach over the traditional MLE approach. We conclude that the Bayesian pproach offers a better learning technique when one lacks of good understanding of the demand pattern in the first few periods. Since inventory policy affects the information acquisition and-the demand distribution updating process, how to determine the optimal inventory policy when the demand distribution is yet to be learned is the focus of the latter part of the thesis. We investigate the effect of demand censoring on the optimal policy in newsvendor inventory models with general parametric demand distribution and unknown parameter values. We provide theoretical proof of the conjecture that it is better off to adopt a higher than the myopic optimal policy in the initial periods when demand is learned in a censoring system. We show that the newsvendor problem with observable lost sales reduces to a sequence of single-period problems while the newsvendor problem with unobservable lost sales requires a dynamic analysis. We explore the economic rationality for this observation and illustrate it with numerical examples.

The three essays in this thesis address various problems in the general area of supply chain management. In general, supply chain management is concerned with management of the flow of goods, information, and funds among supply chain members, such as suppliers, manufacturers, distributors, retailers, and consumers. As such, its scope includes timing and quantity of material flow, logistics, improving efficiencies in problems with several decision makers, etc. The first essay in this thesis considers the problem of improving coordination in a decentralized system of retailers, while the second one addresses stability and profitability of Internet-based supply exchange alliances. The third essay analyzes a logistics problem, of finding an optimal route for a capacitated vehicle which travels on a graph and which can perform pickups and deliveries. In the first essay, we study a three-stage model of a decentralized distribution system with n retailers who each faces a stochastic demand for an identical product. In the first stage, before the demand is realized, each retailer independently orders her initial inventory. In the second stage, after the realization of the demand, each retailer decides what portion of her residual supply/demand she wants to share with the other retailers. In the third stage, residual inventories are transshipped in order to possibly meet residual demands, and an additional profit is allocated among the retailers. We study the effect of implementing various allocations rules in the third stage on the levels of the residual supply/demand the retailers are willing to share with others in the second stage, and the tradeoff involved in achieving a solution which is also optimal for the corresponding centralized system. The second essay is concerned with the formation of Internet-based supply exchange alliances among three or fewer retailers of possibly substitutable products. We provide some conditions, in terms of product substitutability and quality of suppliers, which would lead to the formation of a three member alliance, or a two member alliance, or no alliance at all. We also study the effect of alliance structure and quality of suppliers on the profit of a retailer. The third essay considers a vehicle routing problem with pickups and deliveries (VRPD problem) on some special graphs. Some vertices on the graph represent delivery customers, and other vertices represent pickup customers. The objective is to find a minimum length tour for a capacitated vehicle, which starts at a depot and travels on the graph while satisfying all the requests by the customers without violating the vehicle capacity constraint, and returns to a depot. We have developed linear time algorithms for the VRPD problem on a path and on tree graphs, linear and O (|V| log |V|) algorithm for a VRPD problem defined on a path with parametric initial capacity, and quadratic and O (|V|² log |V|) algorithms for a VRPD problem defined over a cycle graph.

The search for alternative energy sources has increased interests in forest biomass. During the last few years, the sever infestation of the Mountain Pine Beetle (MPB) within the Interior BC forests has led to huge volumes of dead wood that exceed the capacity of the lumber industry. One way to make the most value of the surplus wood is to use it as the feedstock for bioenergy. The forest biomass can be supplied through conventional (roadside residuals), full-tree chipping, or satellite yard systems. This thesis presents the development of a simulation model of supply logistics of forest biomass and its application to a case of supplying MPB-killed biomass from Quesnel Timber Supply Area (one of the most infested areas in the Interior BC) to a potential 300 MW power plant adjacent to the city of Quesnel. The model has the ability of providing estimates of quantity, delivery cost, and moisture content of biomass which are critical in feasibility study of any bioenergy project. The results obtained from simulation model showed a delivery cost of C$45 per oven dry tonne of wood chips to the power plant. The results also revealed that the feedstock recovered from roadside residues in one year meets about 30% of the annual demand of the power plant. Potential increase in the Allowable Annual Cut (AAC) for Quesnel TSA increases the quantity of biomass supplied from roadside residuals. However, as long as the biomass is supplied only through conventional harvesting, increasing the AAC even by 40% does not provide enough feedstock to meet the annual demand of the plant. Using the simulation modeling, this research has the benefit of considering the logistics of forest biomass supply as an integrated and interacting system as well as providing different critical parameters over time. The model also has the potential of considering dynamic and random behavior of the logistics system of supplying forest biomass. The model can be modified and applied to similar cases of conventional forest biomass supply. It also can be extended to other harvesting systems including satellite yard and whole-tree chipping.

Avregleringen av Sveriges järnväg ledde till att Statens Järnvägar delades upp i olika företag, SJ AB bildades som har i uppgift att bedriva lönsam persontrafik. Avregleringen har haft en stor påverkan på hur SJ bedriver sin verksamhet idag samt lett till att komplicerade ägarförhållanden har uppstått i Hagalund. Hagalund är SJ’s största depåanläggning för underhåll av fordon. I samråd med SJ’s Division Fordon och Divisionen för Planering och Trafikledning har vi fått i uppdrag att undersöka hur SJ påverkas om de införskaffar en depå i egen regi. Vi har valt att undersöka SJ ur ett värdekedjeperspektiv. Studien bygger sedan på hur SJ’s värdekedja påverkas om en ny depåanläggning införskaffas. Vi har använt Porters värdekedja som grund till vår studie, det är en analysmetod som kartlägger en organisations värdeskapande aktiviteter. Vi har även tagit del av forskning som gjorts på Porters värdekedja med fokus på resurshantering och informationsprocesser. För att kunna undersöka problemområdet har vi även undersökt och analyserat forskning inom det teoretisk omtrådet vertikal integration. Vertikal integration innebär att en organisation införskaffar en verksamhet till egen regi. Den här studiens syfte är att undersöka hur en organisations värdekedja påverkas om en vertikal integration utförs. För att besvara syftet har vi undersökt hur de sekundära aktiviteterna i SJ’s värdekedja påverkas om en primär värdeskapande aktivitet vertikalt integreras. Vi har även i delsyfte att undersöka vilka effekter den nya depåanläggningen skulle ha på SJ’s produkt tågresor som säljs till kund. Vi besvarar både syftet och delsyftet genom en deduktiv kvalitativ undersökning. Vi använde oss av en semistrukturerad intervjumetod där vi intervjuade respondenter från SJ’s Division Fordon och Divisionen för Planering och Trafikledning. Vår övergripliga slutsats av studien är att en vertikal integration har en inverkan på SJ’s värdekedja. Den vertikala integrationen medför en förbättrad kommunikation samt kontroll av depåverksamheten och dess resurser. SJ’s depåverksamhet blir mer flexibel vilket kan leda till snabbare reaktioner vid oväntade händelser. Kvalitén av produkten tågresor påverkas även positivt. Förutsättningen till dessa fördelar är att SJ har en god kommunikation med nya depån samt införskaffar de resurser som krävs.

The Italian labour market seems unable to allocate a significant fraction of the working age population efficiently. The gap between the employment rate in Italy and in the other developed economies is foremost attributable to the low employment rates of youth, seniors and women. The low employment rates of these three groups are due to several factors limiting both labour demand and labour supply. For women in particular, constraints on the allocation of time play a crucial role in determining labour supply behaviour. In this thesis we try to understand how non-standard time constraints may affect the behaviour of women, and their labour supply in particular. In the first chapter we study how the constraints on work-schedules affect the time allocation of workers in Italy. For a large fraction of employed individuals the work schedule is very rigid, as a consequence of outdated industrial relations. In order to understand whether constraints on the work-schedule produce significant effects on the allocation of time of wage/salary workers in Italy, we exploit the intrinsic differences between them and self employed workers. In fact, one of the main features of self-employment is the greater control over the days worked and daily hours of work. We use the last wave of the Italian time use survey (2008-2009) to provide evidence that the distribution of hours of work of self-employed workers is much more dispersed than that of wage/salary workers and that average standard deviation of their daily minutes of work within a week is significantly larger. Then we show that self-employed workers respond more to shocks affecting the value of leisure. We show that on sunny days the increase of leisure and the reduction of work are significantly larger for self-employed workers. We address whether unobservable characteristics, such as preferences for leisure and for outdoor activities in particular, determine this differential response and find no evidence for this. We interpret the differential response to weather shocks as a consequence of the time constraints on work-schedules. This evidence is relevant for female labour force participation since in Italy a large fraction of women choose not to work because they would otherwise not be able to reconcile family and work responsibilities. In the second chapter we study the Added Worker Effect (AWE). The retrospective questions provided by the new labour force survey allow identification of transitions between labour market states in a 12 month time-window. Since we are able to identify the reason for the husband’s job loss, we distinguish between transitions associated with low or high income losses. We find that both the wife’s probability of joining the labour force and that of finding a job increase when the husband is dismissed or he is forced to quit his job for health reasons, two cases of usually high income losses. Moreover, we estimate the wife’s full transition matrix between labour market states and we find that the loss of a job by a husband increases the probability that his wife will enter the iv labour force. Finally, we provide some descriptive evidence that time constraints can also impact the magnitude of the AWE. Focusing on mothers with young children, we show that the estimated AWE is positively correlated with the regional provision of child care services. The third chapter is based on the time use files of the Canadian General Social Survey. We study how Sunday shopping deregulation changed the time allocation of women, with a particular focus on those with children. The empirical analysis relies on the provincial variation in the time of the policy change. Our results suggest that women with children, who usually face stringent time constraints, respond to the policy change by substituting weekday shopping with Sunday shopping. The amount of time these women save from doing shopping on weekdays allows them to increase their minutes of work. On Sunday, shopping increases at the expense of leisure. The main result of this chapter is that the labour supply of mothers may change even when non-obvious constraints on the allocation of time change.

This thesis examines the impact of farm level cost efficiency on quota trading in a supply regulated industry. Comparative statics illustrate the role of cost efficiency in quota transfers. For estimation purposes, the dependent variable; net quota purchases is specified both quantitatively and qualitatively and modelled by a linear regression model and multinomial logit model, respectively. Empirical results indicate that variation in cost efficiency does not have a significant effect on the sample producers’ decision to purchase quota. Meanwhile, quota purchasers are younger producers, with large herds, underutilized barn space, and had purchase quota in the previous year. / OMAFRA funding code: 200222

This thesis addresses the issue of the existence of a causal relationship between the change in the food component of the consumer price index and change in the money supply (money base and M1) by using monthly Canadian data from January 1968 to March 1997. A bivariate vector autoregressive (VAR) model is used to describe the relationship between money supply and food price on the basis of identifying the two conditions that the three series are first difference stationary series and the money stock and price series are not cointegrated. Saunders' lag order selection criterion developed from Akaikes final prediction error (FPE), and Hsiao's lag selection procedure are used to identify the order of lags of each variable in VAR model. The models perform well through all diagnostic checks. All hypotheses are tested by using the likelihood ratio statistic and the chi2-statistic. The Granger test of causality is discussed and implemented in this research. By comparing the causality results of the seasonally adjusted series with those of seasonally unadjusted series we find that they are very sensitive to the seasonal adjustment of the series. For the seasonally adjusted series there is no relationship between money base (MB) and the food component of the consumer price index (FCPI) and there is a unidirectional causal relationship between M1 and FCPI (from M1 to FCPI). But for the seasonally unadjusted series there is a feedback relationship between M1 and FCPI and there is a unidirectional flow from MB to FCPI. The difference of the results is consistent with the findings of Sargent and other writers.

The purpose of this thesis is to explain theoretically and empirically the demand for international reserves by the major industrialized countries in the context of the present highly integrated and extremely volatile international financial system. The reserves demand behaviour of each of the G7 countries along with seven non-G7 industrialized countries have been empirically examined. The demand functions are estimated using the cointegration approach on autoregressive distributed lag and simple distributed lag models. / This study has revealed that a country's reserve demand is significantly influenced by its level of capital flows in addition to the traditionally used trade flow variables. It is shown that the greater the external vulnerability of an economy as measured by its net capital flows in relation to its GNP, the higher is its demand for international reserves. The results have striking similarity for all the 14 industrialized countries despite their structural and institutional differences. / This study points to the need of international monetary policy coordination to reduce large fluctuations in exchange rates and lessen massive flows of speculative capital which carry a potential threat of becoming inflationary.

No description available.

No abstract available. / Thesis (M.A.)-University of Natal, Durban, 1959.