<p>A value is the concept of the desirable. If those who develop information systems and those who use information systems have different values, the value gap can lead to serious consequences. Two methods are developed and tested in this thesis to measure the value systems of developers, users and other participants in the information system development process: one based on a personal value questionaire (PVQ) and the other based on multi-attribute value theory (MAVT).</p> <p>A framework for information systems (IS) relevant values was developed to enumerate and organize the values to be measured into three groups: economic, technical and socio-political-psychological.</p> <p>There were 86 values enumerated, which were used in the PVQ method to survey 132 system developers and 47 47 system users in 13 firms. Developers and users were found to have similar values with respect to economic and technological items but sharply differing values in the socio-political-psychological group.</p> <p>A condensed set of items consisting of two economic, five technological and four socio-political items, were organized in a hierarchical struture, for the MAVT method. Preference conditions were assessed and values were measured using the rating scale approach. Three subjects were interviewed in depth; two produced additive multi-attribute value functions, while one produced a multiplicative function</p> / Doctor of Philosophy (PhD)

<p>Several methods have been proposed and tested for calculating lower bounds on the objective function of facilities problems. These methods contribute to the efficiency of iterative solution methods by allowing the user to terminate the computation process when the objective function comes within a predetermined fraction of the optimal solution. Two of the existing bounding methods have been presented only for single facility location models with Euclidean (straight-line) distances. One of these methods uses the dual of the single facility location model to compute a lower bound. This thesis introduces a method for generating a feasible dual solution from any primal solution by means of a projection matrix. The projection matrix method is applied to single and multi-facility models. The second bounding method, which involves the solution of a rectilinear distance model to obtain a lower bound, is extended in this thesis to include a generalized, distance function and the multi-facility situation. Computation results for the two new bounding methods are compared with several existing bounding methods. These results should aid practitioners in selecting an appropriate bounding method for an iterative solution method to a facilities location problem.</p> / Doctor of Philosophy (PhD)

<p>In this dissertation, we look at two families of distance predicting functions, the ℓkpθ norm family and the block norm family, that can be used for modelling actual distances. To compare the distance-predicting accuracy of the two families, an empirical study is conducted. Two types of regions, which are large geographic regions and urban centres, are used in the study. In the large geographic regions, actual distances between cities in each region are modelled, whereas in the urban centres, actual distances within a city are modelled. To evaluate the accuracy of the different norms, two goodness-of-fit criteria are employed. For the block norms, new procedures that determine global solutions for the criteria are developed. Normality assumptions regarding the individual terms of the criteria are examined since these terms are used to formulate statistical tests that are sensitive to departures from normality. A new criterion for evaluating the accuracy of a distance predicting function is developed. This criterion, unlike the other two criteria, is impartial both to short actual distances and to long actual distances. The criterion is used to evaluate the accuracy of the ℓkpθ norm for the geographic regions that were used in the empirical study. A statistical analysis of the errors from this new criterion leads to the development of confidence intervals for unknown distances in any geographic region. The results from this thesis will help an analyst select an appropriate distance predicting function to model actual distances in any application. Further, a new measure for evaluating distance predicting functions may be considered by an analyst, and confidence intervals for unknown distances can be easily constructed.</p> / Doctor of Philosophy (PhD)

<p>This thesis deals with game theory and its applications in management science and focuses upon some management science areas such as inventory control and new product development. Some interesting theoretical findings and new policies are obtained by using the game theoretical approach to analyze certain management science problems. The discussion starts with a review of static game theory models and their applications in management science. Of particular interest here is the state of the art of game theory as an analytical technique in management science. Chapters Two and Three discuss the discount problem. Particular attention is paid to the gaming nature and the buyer's demand aspect of the problem. It is shown that, if they work independently and rationally, the seller and the buyer can gain from price discount only if it can attract more demand from the buyer. Nevertheless, they can gain from quantity discount even if demand is constant. Quantity discount is always better than a price discount for the seller and, in certain situations, can be very efficient in obtaining the maximum profit. Optimal decisions are obtained for both the seller and the buyer under various conditions. Chapter Four studies the order quantities of substitutable products with stochastic demands. This analysis extends the newsboy problem analysis into situations with three or more players. It is shown that there is one Nash equilibrium for the problem. If any player(s) acts irrationally, the other players' decision problem reduces to the one without the irrational player(s). If cooperation is possible, their decisions depend on whether side payments are allowed. If side payments are allowed, they will determine their order quantities together. If side payments are not allowed, secure strategies exist for each player. It is also shown that all players' cooperation is often worthwhile and feasible. Chapter Five analyzes the growth of new repeat purchasing products. It is shown that markets of repeat purchasing products will never saturate like that of consumer durable products unless customers are extremely loyal to at least one product. For new repeat purchasing products, the optimal advertising strategy is increasing at the introductory stage and then decreasing or possibly terminating after some time and, the optimal service strategy is monotonically increasing at the introductory stage and then possibly maintained constant at a certain level. Especially, more advertising should be done at early stages against competitors' advertising campaign. The game is solved analytically for optimal strategies in the case where all the control functions representing the effects of advertising and service are linear in the control variables. Finally, the main findings and possible extensions to this research are briefly summarized in Chapter Six. (Abstract shortened by UMI.)</p> / Doctor of Philosophy (PhD)

<p>This thesis represents research in the combined areas of inventory and maintenance. It analyzes two independent inventory and maintenance problems under dynamic systems: (i) a production and maintenance problem and (ii) a repairable-item inventory problem. For each problem, the thesis develops a new control model and proposes a simultaneous determination of optimal inventory and maintenance policies. The first part of the thesis examines a production process where the process performance deteriorates over time in the absence of preventive maintenance. First, it develops a new finite-time control model for optimal production and maintenance decisions by combining a dynamic maintenance model with a production control model. Second, it derives the necessary conditions for optimal production and maintenance controls using the maximum principle. Finally, it proposes two optimization algorithms for numerically solving the necessary conditions already derived. The second part of the thesis considers the repairable-item inventory problem, which may be faced at each period by the inventory manager responsible for determining the optimum quantities to purchase new serviceable units, to repair and to junk returned repairable units in order to satisfy random demand for serviceable units. First, it proposes an inventory model for repairables, incorporating several important features. The model includes a periodic review policy, random demand, lost sales for unsatisfied demand, set-up costs for ordering and repair, and a dynamic return process. Second, it employs a quite different solution methodology from what the previous research has used. The approach employed here is a 'Markov decision process (MDP)'. With this approach, the inventory problem is remodelled as a discrete-time Markov decision problem with two-dimensional state and three-dimensional decision spaces and then solved for finite-time planning horizon using the backward induction algorithm and for infinite-time planning horizon using the method of successive approximations. Finally, it introduces and utilizes two acceleration techniques, the error bounds approach and State Decomposition by Dimension (SDD), for speeding up the convergence of the computational methods described above.</p> / Doctor of Philosophy (PhD)

This research study has produced advances in the understanding of communities within a complex network. A community in this context is defined as a subgraph with a higher internal density and a lower crossing density with respect to other subgraphs. In this study, a novel and efficient distance-based ranking algorithm called the Correlation Density Rank (CDR) has been proposed and is utilized for a broad range of applications, such as deriving the community structure and the evolution graph of the organizational structure from a dynamic social network, extracting common members between overlapped communities, performance-based comparison between different service providers in a wireless network, and finding optimal reliability-oriented assignment tasks to processors in heterogeneous distributed computing systems. The experiments, conducted on both synthetic and real datasets, demonstrate the feasibility and applicability of the framework.

Apparently fraud is a growth industry. The monetary losses from Internet fraud have increased every year since first officially reported by the Internet Crime Complaint Center (IC3) in 2000. Prior research studies and third-party reports of fraud show rates substantially higher than eBay’s reported negative feedback rate of less than 1%. The conclusion is most buyers are withholding reports of negative feedback. Researchers Nikitov and Stone in a forensic case study of a single opportunistic eBay seller found buyers sometimes embedded negative comments in positive feedback as a means of avoiding retaliation from sellers and damage to their reputation. This category of positive feedback was described as “negative-positive” feedback. An example of negative-positive type feedback is “Good product, but slow shipping.” This research study investigated the concept of using negative-positive type feedback as a signature to identify potential opportunistic sellers in an online auction population. As experienced by prior researchers using data extracted from the eBay web site, the magnitude of data to be analyzed in the proposed study was massive. The nature of the analysis required - judgment of seller behavior and contextual analysis of buyer feedback comments – could not be automated. The traditional method of using multiple dedicated human raters would have taken months of labor with a correspondingly high labor cost. Instead, crowdsourcing in the form of Amazon Mechanical Turk was used to reduce the analysis time to a few days and at a fraction of the traditional labor cost. The research’s results found that the presence of subtle buyer behavior in the form of negative-positive type feedback comments are an inter-buyer signal indicating that a seller was behaving fraudulently. Sellers with negative-positive type feedback were 1.82 times more likely to be fraudulent. A correlation exists between an increasing number of negative-positive type feedback comments and an increasing probability that a seller was acting fraudulently. For every one unit increase in the number of negative-positive type feedback comments a seller was 4% more likely to be fraudulent.

There is substantial evidence concerning the inability to achieve desired results and impact through what are commonly described as IS or IT projects, or implementation. The UK health sector provides a fertile ground for research, at a time of unprecedented investment, but with what is perceived to be a relatively poor record of achievement. Mental health services are held to be particularly problematic. This thesis explores the part played by technical, informational, organisational and human aspects, the relationship between these, and how in practice they are interpreted within what is defined as IS implementation. The aims were, a) definitional, concerning the specification of IS implementation, b) context appraising, to examine the impact of the host (mental health) context on both process and results, and through these c) problem solving, to propose an approach to IS implementation based on theory and practice. Drawing from interpretive theory, soft systems methodology and social cognitive theory an in-depth, longitudinal comparison study was performed, principally focussing on a single UK mental health Trust, and a directorate within that Trust. A multi-method approach included document review, questionnaire, structured and semi-structured interview, definitional exercises, focus groups, and action research. Findings concern the inability of organisations to manage the complexity of the process of implementation within challenging, multi-faceted contexts. To address the causes rather than symptoms of this difficulty it is necessary to re-interpret implementation itself, and its human element. A broad definition was proposed as a basis for an inclusive and balanced approach, and an Interface Management toolkit was produced. It is proposed that implementation should be considered and approached in practice as a dialectical situation, interpreting implementation as change within an organisation which encompasses technology. Alternative existing and proposed ideologies of change are suggested to frame a productive relationship between theory and practice.

published_or_final_version / Management Studies / Doctoral / Doctor of Philosophy

published_or_final_version / Business / Master / Master of Philosophy