No description available.

No description available.

No description available.

No description available.

A computer simulation experiment was conducted to evaluate and compare five individual forecasting models across nine different demand patterns. The models were based on the Medical Materiel Management System used by the US Air Force hospitals. Results indicated the best model varied depending on the demand pattern, the safety stock level, the noise level of the demand pattern, and the measure of forecast error. Across all demand patterns, exponential smoothing and 12-month moving average were best for the short term forecast used by the system, regardless of noise level in the demand patterns. Analysis of models within a single demand pattern showed, in most cases, several models as ranking equally well. When overall system requirements were considered, the exponential smoothing method was by far the best choice.

Price and inventory decisions are key levers of profit for firms. A manager needs to understand the impacts of pricing, ordering and stocking decisions not only on today's operations but also on future demand. In this dissertation we investigate these intertwining decisions by incorporating inter-temporal effects of pricing decisions through reference prices. We introduce three significant extensions to reference price models to provide more meaningful insight into pricing, inventory and ordering decisions. We first present a threshold reference model. The threshold model incorporates zones of insensitivity around expected price that moderate the reference impacts on demand. This provides a rigourous model that is flexible enough to handle different pricing strategies such as single everyday low pricing (EDLP), high-low pricing (HiLo) and other general price cycles. We develop two solution approaches and provide computational results. We next introduce a reference model with stochastic demand. There is considerable previous research supporting the consideration of variability in pricing and inventory decisions and this is especially true in the context of inter-temporal demand interactions based on pricing decisions. We find that the introduction of stochastic elements can actually increase or decrease the length of the price cycle for some consumers in a reference model depending on the parameters of the model. This extends the stochastic demand model and bridges to reference models for improved managerial insight. The final model presented is the dynamic lot sizing model. When prices and production decisions or order quantities are determined simultaneously the interactions need to be considered to optimize profits. The reference model incorporates the inter-temporal price effects to provide a clearer picture of the optimal decision. The inclusion of reference effects does change the optimal decision. / Thesis / Doctor of Philosophy (PhD)

In this thesis, we study three periodic-review, finite-horizon inventory systems in the presence of supply and demand uncertainties. In the first part of the thesis, we study a multi-period single-station problem in which supply uncertainty is modeled by partial supply. Formulating the problem under a robust optimization (RO) framework, we show that solving the robust counterpart is equivalent to solving a nominal problem with a modified deterministic demand sequence. In particular, in the stationary case the optimal robust policy follows the quasi-(s, S) form and the corresponding s and S levels are theoretically computable. In the second part of the thesis, we extend the RO framework to a multi-period multi-echelon problem. We show that for a tree structure network, decomposition applies so that the optimal single-station robust policy remains valid for each echelon in the tree. Furthermore, if there are no setup costs in the network, then the problem can be decomposed into several uncapacitated single-station problems with new cost parameters subject to the deterministic demands. In the last part of the thesis, we consider a periodic-review Assemble-To-Order (ATO) system with multiple components and multiple products, where the inventory replenishment for each component follows an independent base-stock policy and product demands are satisfied according to a First-Come-First-Served (FCFS) rule. We jointly consider the inventory replenishment and component allocation problems in the ATO system under stochastic component replenishment lead times and stochastic product demands. The problems are formulated under the stochastic programming (SP) framework, which are difficult to solve exactly due to a large number of scenarios. We use the sample average approximation (SAA) algorithms to find near-optimal solutions, which accuracy is verified by the numerical experiment results. / Thesis / Doctor of Philosophy (PhD)

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The purpose of this study was to examine differences in the changes in levels of differentiation, as measured by the Differentiation of Self Inventory (DSI) (Knauth & Skowron, 2004), that occurred among high school students who participated in a semester-long (n = 69) and year-long (n = 119) AFS (formerly known as American Field Service) program and a control group (n = 75) that did not study abroad. Gender of student and level of individualism of host country were also examined. The DSI full scale and four subscales: emotional reactivity, I position, emotional cutoff, and fusion with others were used to assess levels of differentiation. This study was a non-equivalent control group experimental pretest-posttest design. Pretest scores were used as the covariate in the posttest ANCOVA. Results revealed that female students who studied abroad for both one year and one semester experienced significant increases in levels of differentiation as measured by the DSI full scale versus female students who did not study abroad. There were no significant differences among males who studied abroad for one year, one semester or not at all. Additional results indicate a significant difference in changes in level of differentiation, as measured by the DSI full scale, between genders in the control group and the semester abroad group. Additional gender differences were revealed on the emotional reactivity and fusion with others subscales. Level of host country's individualism was not a significant factor. Results support previous literature which states that males and females engage in differing processes when forming their identity. Results also demonstrate that studying abroad is a meaningful life experience significant enough to assist females with increasing levels of differentiation. Additional results, a discussion of the results, limitations, and implications for practice and research are also provided. / Ph. D.

A descriptive case study examined the gender differences concerning computer technology (IT) by a convenience sample (N = 180, 76%) of 11 th and 12 th graders at an elite public high school, recently named the "second best high school in America" (Newsweek, 2000), in suburban Northern Virginia. The purpose of the study was to examine the apparent discrepancy in male and female differences in computer use, interests, and attitudes. The research design included a student questionnaire combining the Computer Attitude Rating Scale (CARS, Heinssen, Glass, & Knight, 1987) and the Attitudes toward Computer Technology (ACT, Delcourt & Kinzie, 1993) with demographic and academic data (GPA, PSAT, and SAT I), and the Strong Interest Inventory (Strong, 1994). Chi-square tests of association for categorical data and t tests for independence of means for metric data were used to analyze the data, which resulted in several statistically significant relationships (p = < .05) and meaningful effect sizes (> .70). The results were higher mean scores for the Strong Realistic General Occupational Theme (males) and Artistic Theme (females); the Athletic and Mechanical Basic Interest Scales (males) and Music/Drama, Art, Culinary Arts, and Social Service Scales (females), and Risk-Taking Personal Style Scales (males) and Working Style with People (females). Females also had higher GPAs, levels of computer anxiety, resistance to technology, and avoidance of careers and study in computer fields. Females chose Pre-Medicine majors to help others and males chose Computer Science majors to gain financial rewards. The implications for practice and research included: female technology internships, 9th grade mechanical and technical training, computer anxiety group counseling, cooperative learning and hands on instruction, female-friendly computer and computer science classes, equal access to computers at all grade levels, student-parent information programs concerning the many opportunities and high paying jobs available in computer technology, female orientated computer games, and more non-linear computer programs and activities that encourage females to "have fun" with computers and not view them as machines. A longitudinal study of the current sample and research at other grade levels and locations were recommended. / Ph. D.