In decision theory the process of selecting the best option is called preferential choice. Many personal, business, and professional preferential choice decisions are made every day. In these situations, a decision maker must select the optimal option among multiple alternatives. In order to do this, she must be able to analyze a model of her preferences with respect to the objectives that are important to her. Prescriptive decision theory suggests several ways to effectively develop a decision model. However, these methods often end up too tedious and complicated to apply to complex decisions that involve many objectives and alternatives. In order to help people make better decisions, an easier, more intuitive way to develop interactive models for analysis of decision contexts is needed. The application of interactive visualization techniques to this problem is an opportune solution. A visualization tool to help in preferential choice must take into account important aspects from both fields of Information Visualization and Decision Theory. There exists some proposals that claim to aid preferential choice, but some key tasks and steps from at least one of these areas are often overlooked. An added missing element in these proposals is an adequate user evaluation. In fact, the concept of a good evaluation in the field of information visualization is a topic of debate, since the goals of such systems stretch beyond what can be concluded from traditional usability testing. In our research we investigate ways to overcome some of the challenges faced in the design and evaluation of visualization systems for preferential choice. In previous work, Carenini and Lloyd proposed ValueCharts, a set of visualizations and interactive techniques to support the inspection of linear models of preferences. We now identify the need to consider the decision process in its entirety, and to redesign ValueCharts in order to support all phases of preferential choice. We present our task-based approach to the redesign of ValueCharts grounded in recent findings from both Decision Analysis and Information Visualization. We propose a set of domain-independent tasks for the design and evaluation of interactive visualizations for preferential choice. We then use the resulting framework as a basis for an analytical evaluation of our tool and alternative approaches. Finally, we use an application of the task model in conjunction with a new blend of evaluation methods to assess the utility of ValueCharts.

In decision theory the process of selecting the best option is called preferential choice. Many personal, business, and professional preferential choice decisions are made every day. In these situations, a decision maker must select the optimal option among multiple alternatives. In order to do this, she must be able to analyze a model of her preferences with respect to the objectives that are important to her. Prescriptive decision theory suggests several ways to effectively develop a decision model. However, these methods often end up too tedious and complicated to apply to complex decisions that involve many objectives and alternatives. In order to help people make better decisions, an easier, more intuitive way to develop interactive models for analysis of decision contexts is needed. The application of interactive visualization techniques to this problem is an opportune solution. A visualization tool to help in preferential choice must take into account important aspects from both fields of Information Visualization and Decision Theory. There exists some proposals that claim to aid preferential choice, but some key tasks and steps from at least one of these areas are often overlooked. An added missing element in these proposals is an adequate user evaluation. In fact, the concept of a good evaluation in the field of information visualization is a topic of debate, since the goals of such systems stretch beyond what can be concluded from traditional usability testing. In our research we investigate ways to overcome some of the challenges faced in the design and evaluation of visualization systems for preferential choice. In previous work, Carenini and Lloyd proposed ValueCharts, a set of visualizations and interactive techniques to support the inspection of linear models of preferences. We now identify the need to consider the decision process in its entirety, and to redesign ValueCharts in order to support all phases of preferential choice. We present our task-based approach to the redesign of ValueCharts grounded in recent findings from both Decision Analysis and Information Visualization. We propose a set of domain-independent tasks for the design and evaluation of interactive visualizations for preferential choice. We then use the resulting framework as a basis for an analytical evaluation of our tool and alternative approaches. Finally, we use an application of the task model in conjunction with a new blend of evaluation methods to assess the utility of ValueCharts.

In decision theory the process of selecting the best option is called preferential choice. Many personal, business, and professional preferential choice decisions are made every day. In these situations, a decision maker must select the optimal option among multiple alternatives. In order to do this, she must be able to analyze a model of her preferences with respect to the objectives that are important to her. Prescriptive decision theory suggests several ways to effectively develop a decision model. However, these methods often end up too tedious and complicated to apply to complex decisions that involve many objectives and alternatives. In order to help people make better decisions, an easier, more intuitive way to develop interactive models for analysis of decision contexts is needed. The application of interactive visualization techniques to this problem is an opportune solution. A visualization tool to help in preferential choice must take into account important aspects from both fields of Information Visualization and Decision Theory. There exists some proposals that claim to aid preferential choice, but some key tasks and steps from at least one of these areas are often overlooked. An added missing element in these proposals is an adequate user evaluation. In fact, the concept of a good evaluation in the field of information visualization is a topic of debate, since the goals of such systems stretch beyond what can be concluded from traditional usability testing. In our research we investigate ways to overcome some of the challenges faced in the design and evaluation of visualization systems for preferential choice. In previous work, Carenini and Lloyd proposed ValueCharts, a set of visualizations and interactive techniques to support the inspection of linear models of preferences. We now identify the need to consider the decision process in its entirety, and to redesign ValueCharts in order to support all phases of preferential choice. We present our task-based approach to the redesign of ValueCharts grounded in recent findings from both Decision Analysis and Information Visualization. We propose a set of domain-independent tasks for the design and evaluation of interactive visualizations for preferential choice. We then use the resulting framework as a basis for an analytical evaluation of our tool and alternative approaches. Finally, we use an application of the task model in conjunction with a new blend of evaluation methods to assess the utility of ValueCharts. / Science, Faculty of / Computer Science, Department of / Graduate

Multisystem length limits are a popular output control implemented to regulate harvest of many gamefishes. Evaluating the direct effects of length limits is crucial in selecting a regulation, but to my knowledge, no formal methodology exists to model length limits for multiple systems. Without a formalized process, complexities associated with multisystem scales of management can preclude effective communication and interpretation of information. I created a quantitative decision model as an approach for comparing length limits applied to multiple systems. This approach combined an extension of the Beverton-Holt yield-per-recruit function and an additive utility function to compare multisystem length limits. I also conducted a sensitivity analyses to clarify the effect of input parameters and uncertainty on the expected utility, and on performance metrics. This approach provides a consistent methodology for evaluating multisystem length limits, and as a decision support tool, can improve transparency of the length-limit-selection process.

Decision analysis is a quantitative approach to decision-making that could bridge the gap between decisions based solely on evidence and the unique values and preferences of individual patients, a feature especially important when existing clinical evidence cannot support clear recommendations and there is a close balance between harms and benefits for the treatment options under consideration. Low molecular weight heparin for the prevention of venous thromboembolism (VTE) during pregnancy represents one such situation. The objective of this thesis is to explore the use of a decision analysis intervention for shared decision-making for thromboprophylaxis during pregnancy. This thesis begins with a scoping review that explores the ways in which decision analysis has been used to inform shared decision-making encounters, highlighting key challenges for implementing and evaluating this type of intervention. This is followed by a protocol that presents the methodology of an explanatory sequential mixed methods pilot study for the Decision Analysis in SHared decision making for Thromboprophylaxis during Pregnancy (DASH-TOP) tool. This tool was pilot tested through interviews of eligible women in Canada and Spain who were facing the treatment decision for the prevention of VTE in the antenatal period. While the tool was well received by patients, more effective ways of obtaining patient preferences and presenting the decision analysis results are required to enhance shared decision-making interactions. Finally, this thesis concludes with a reflection on the lessons learned from developing and evaluating a decision analysis intervention for shared decision-making. The insights from this research have informed the development of an integrated online shared decision-making tool for VTE in the antenatal period, which the DASH-TOP team plans to evaluate in a randomized controlled trial. It is hoped that this information will also provide guidance to researchers interested in developing or evaluating decision analysis interventions for other clinical decisions. / Dissertation / Doctor of Philosophy (PhD)

Metastatic epidural spinal cord compression (MESCC) occurs when tumour invades the epidural space and compresses the spinal cord. Despite Level 1 evidence that surgery is the most effective treatment for MESCC, there is controversy regarding the role of surgery because of fear that patients who have a short survival will spend a large fraction of their remaining life recovering from surgery and potential complications. This controversy could be resolved by decision-analysis of MESCC treatments using quality-adjusted-life-years (QALYs). There have been two barriers to conducting decision-analysis of QALYs for MESCC: (a) lack of utility data, and (b) skepticism regarding decision-analysis. The first four research chapters in this thesis address these barriers. The final research chapter reports a decision-analysis of QALYs on the role of surgery in MESCC. Chapter 1 provides background information on the controversy regarding surgical treatment for MESCC and the rationale for each of the subsequent chapters. Chapter 2 reports a psychometric validation study of a web-based utility valuation module for MESCC. In Chapter 3, application of this module to a general population utility valuation study with a market research panel is described. In Chapter 4, the beneficial properties of Bayesian statistical analysis to minimizing “arbitrariness” in probabilistic sensitivity analysis are described in relation to prognostication for MESCC. Chapter 5 presents a strategy for simplifying and enhancing the transparency of Markov cohort simulation. Finally, the work presented in the research chapters is applied in Chapter 6 to conduct Markov cohort simulation to determine if patients with short survival derive net health-related quality-of-life benefit from surgery. Pragmatic research around barriers to decision-analysis of QALYs for MESCC was conducted to resolve the controversy regarding the role of surgery in the treatment of MESCC. Under most circumstances, MESCC patients who can ambulate prior to treatment derive net HRQoL benefit from surgery, even if prognosis is poor. Non-ambulatory patients can derive net HRQoL benefit but only if the morbidity of surgery is relatively low. It is my hope that the work used to address barriers to decision-analysis of QALYs will be disseminated and applied in other clinical problems.

Pharmaceutical R&D is time-consuming, extremely costly and involves great uncertainty. Although there is a broad range of literature on statistical issues in clinical trials, there is not much that focuses directly on the modelling of pre-clinical research. This thesis investigates models and associated software for improving decisionmaking in this area, building on earlier work by the same research group. We introduce a class of adaptive policies called forwards induction policies for candidate drug selection, and show that these are optimal, with a straightforward solution algorithm, within a restricted setting, and are usually close to optimal more generally. We also introduce an adaptive probabilities model that allows the incorporation of learning from a project’s progress into the planning process. Real options analysis in the evaluation of project value is discussed. Specifically, we consider the option value of investing in clinical trials once a candidate drug emerges from pre-clinical research. Simulation algorithms are developed to investigate the probability distributions of the total reward, total cost, profitability index and the required future resource allocations of a pharmaceutical project under a given allocation plan. The ability to simulate outcome distributionsmeans that we can also compare the riskiness of different projects and portfolios of projects.

As usinas de açúcar e álcool no Estado de Alagoas têm grande importância econômica, para usar sua capacidade instalada torna-se necessário o uso de técnicas que aumentem sua produtividade e/ou diminuam os custos de produção da cana-deaçúcar. A irrigação suplementar apresenta-se como uma destas alternativas. A tecnologia de irrigação se tornou uma alternativa rentável para as condições do Estado de Alagoas. Com base na análise de viabilidade da tecnologia de irrigação em canasoca, a árvore de decisão, um instrumento de análise de decisão, foi utilizada na avaliação dos valores esperados dos retornos associados a diferentes alternativas disponíveis para a escolha do tomador de decisão. Levando-se em considerações as condições analisadas de irrigação suplementar durante o primeiro estádio de desenvolvimento da cana-de-açúcar (ciclo soca), no litoral Sul do Estado de Alagoas, os resultados do estudo permitiram obter as seguintes conclusões: (a) existe um grande potencial de viabilidade da tecnologia de irrigação do início de ano (janeiro), considerando os benefícios diretos e indiretos de aumento de produtividade agrícola, maior longevidade das soqueiras, redução de preparo de solo e plantio, tratos culturais e transporte de cana; (b) os valores obtidos com os benefícios diretos e indiretos da irrigação suplementar da cana-soca de março indicaram inviabilidade econômica para tecnologia de irrigação; (c) a análise de sensibilidade dos resultados das receitas líquidas esperadas nas árvores de decisão das variáveis (lâmina de irrigação, custo fixo e custo operacional), mostrou que o efeito da variável lâmina de irrigação sobre as receitas líquidas, é inversamente proporcional aos efeitos das variáveis de custos fixo e operacional. (d) a receita líquida esperada apresenta pequena sensibilidade às variáveis de custos com tratos culturais de soqueiras e preparo de solo e plantio. / The plant of sugar mills and alcohol destilleries of the State of Alagoas have great economical importance, to fulfill your installed capacities necessary the use of techniques that increase your productivity and/or reduce the costs of production of the sugar-cane. The supplementary irrigation is one of the available alternatives. The irrigation technology a profitable alternative for the conditions of the State of Alagoas. With base in analysis of viability of the irrigation technology in cane-beats, the decision trees, an instrument of decision analysis, was utilized in the evaluating the expected values of different alternatives faced by the decision maker, taking in considerations the analyzed conditions of the supplementary irrigation during the first stadium of development of the sugar-cane (ratoon cycle) in the coast South of Alagoas, the results of the study lead the following conclusions: (a) a great potential of viability of the technology of irrigation of the year beginning (january), considering the direct and indirect benefits of increase of productivity agricultural, larger longevity of the ratoon, reduction of soil preparation and planting, cultural treatments and cane transport; (b) the values obtained with the direct and indirect benefits of the supplemental irrigation of the canebeats of march they indicated economical inviability for irrigation technology; (c) the analysis of sensibility of the results of the expected net benefit in the decision trees of the variables (irrigation sheet, fixed cost and operational cost), showed that the effect of the variable irrigation sheet on the net benefit, is inversely proportional to the effects of the variables of fixed and operational costs. (d) the expected net benefit presents small sensibility to the variables of costs with cultural treatments of ratoon and soil preparation and planting.

As usinas de açúcar e álcool no Estado de Alagoas têm grande importância econômica, para usar sua capacidade instalada torna-se necessário o uso de técnicas que aumentem sua produtividade e/ou diminuam os custos de produção da cana-deaçúcar. A irrigação suplementar apresenta-se como uma destas alternativas. A tecnologia de irrigação se tornou uma alternativa rentável para as condições do Estado de Alagoas. Com base na análise de viabilidade da tecnologia de irrigação em canasoca, a árvore de decisão, um instrumento de análise de decisão, foi utilizada na avaliação dos valores esperados dos retornos associados a diferentes alternativas disponíveis para a escolha do tomador de decisão. Levando-se em considerações as condições analisadas de irrigação suplementar durante o primeiro estádio de desenvolvimento da cana-de-açúcar (ciclo soca), no litoral Sul do Estado de Alagoas, os resultados do estudo permitiram obter as seguintes conclusões: (a) existe um grande potencial de viabilidade da tecnologia de irrigação do início de ano (janeiro), considerando os benefícios diretos e indiretos de aumento de produtividade agrícola, maior longevidade das soqueiras, redução de preparo de solo e plantio, tratos culturais e transporte de cana; (b) os valores obtidos com os benefícios diretos e indiretos da irrigação suplementar da cana-soca de março indicaram inviabilidade econômica para tecnologia de irrigação; (c) a análise de sensibilidade dos resultados das receitas líquidas esperadas nas árvores de decisão das variáveis (lâmina de irrigação, custo fixo e custo operacional), mostrou que o efeito da variável lâmina de irrigação sobre as receitas líquidas, é inversamente proporcional aos efeitos das variáveis de custos fixo e operacional. (d) a receita líquida esperada apresenta pequena sensibilidade às variáveis de custos com tratos culturais de soqueiras e preparo de solo e plantio. / The plant of sugar mills and alcohol destilleries of the State of Alagoas have great economical importance, to fulfill your installed capacities necessary the use of techniques that increase your productivity and/or reduce the costs of production of the sugar-cane. The supplementary irrigation is one of the available alternatives. The irrigation technology a profitable alternative for the conditions of the State of Alagoas. With base in analysis of viability of the irrigation technology in cane-beats, the decision trees, an instrument of decision analysis, was utilized in the evaluating the expected values of different alternatives faced by the decision maker, taking in considerations the analyzed conditions of the supplementary irrigation during the first stadium of development of the sugar-cane (ratoon cycle) in the coast South of Alagoas, the results of the study lead the following conclusions: (a) a great potential of viability of the technology of irrigation of the year beginning (january), considering the direct and indirect benefits of increase of productivity agricultural, larger longevity of the ratoon, reduction of soil preparation and planting, cultural treatments and cane transport; (b) the values obtained with the direct and indirect benefits of the supplemental irrigation of the canebeats of march they indicated economical inviability for irrigation technology; (c) the analysis of sensibility of the results of the expected net benefit in the decision trees of the variables (irrigation sheet, fixed cost and operational cost), showed that the effect of the variable irrigation sheet on the net benefit, is inversely proportional to the effects of the variables of fixed and operational costs. (d) the expected net benefit presents small sensibility to the variables of costs with cultural treatments of ratoon and soil preparation and planting.

This thesis deals with sequential and adaptive methods for clinical trials, and how such methods can be used to achieve efficient clinical trial designs. The efficiency gains that can be achieved through non-adaptive group sequential methods are well established, while the newer adaptive methods seek to combine the best of the classical group sequential framework with an approach that gives increased flexibility. Our results show that the adaptive methods can provide some additional efficiency, as well as increased possibilities to respond to new internal and external information. Care is however needed when applying adaptive methods. While sub-optimal rules for adaptation can lead to inefficiencies, the logistical challenges can also be considerable. Efficient non-adaptive group sequential designs are often easier to implement in practice, and have for the cases we have considered been quite competitive in terms of efficiency. The four problems that are presented in this thesis are very relevant to how clinical trials are run in practice. The solutions that we present are either new approaches to problems that have not previously been solved, or methods that are more efficient than the ones currently available in the literature. Several challenging optimisation problems are solved through numerical computations. The optimal designs that are achieved can be used to benchmark new methods proposed in this thesis as well as methods available in the statistical literature. The problem that is solved in Chapter 5 can be viewed as a natural extension to the other problems. It brings together methods that we have used to the design of individual trials, to solve the more complex problem of designing a sequence of trials that are the core part of a clinical development program. The expected utility that is maximised is motivated by how the development of new medicines works in practice.