Dissertations / Theses on the topic 'Mixed model method'
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Sima, Adam. "Accounting for Model Uncertainty in Linear Mixed-Effects Models." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/2950.
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Standard statistical decision-making tools, such as inference, confidence intervals and forecasting, are contingent on the assumption that the statistical model used in the analysis is the true model. In linear mixed-effect models, ignoring model uncertainty results in an underestimation of the residual variance, contributing to hypothesis tests that demonstrate larger than nominal Type-I errors and confidence intervals with smaller than nominal coverage probabilities. A novel utilization of the generalized degrees of freedom developed by Zhang et al. (2012) is used to adjust the estimate of the residual variance for model uncertainty. Additionally, the general global linear approximation is extended to linear mixed-effect models to adjust the standard errors of the parameter estimates for model uncertainty. Both of these methods use a perturbation method for estimation, where random noise is added to the response variable and, conditional on the observed responses, the corresponding estimate is calculated. A simulation study demonstrates that when the proposed methodologies are utilized, both the variance and standard errors are inflated for model uncertainty. However, when a data-driven strategy is employed, the proposed methodologies show limited usefulness. These methods are evaluated with a trial assessing the performance of cervical traction in the treatment of cervical radiculopathy.
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Kjellsson, Maria C. "Methodological Studies on Models and Methods for Mixed-Effects Categorical Data Analysis." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9333.
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Oldham, Alexis Jean. "Modulation of lipid domain formation in mixed model systems by proteins and peptides." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-1/r1/oldhama/alexisoldham.pdf.
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Rigaki, Anastasia. "Teachers of Greek Model Experimental High : Schools and Lifelong Learning: a mixed methods approach." Thesis, Linköpings universitet, Institutionen för beteendevetenskap och lärande, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-113294.
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Lifelong Learning is a key concept in modern ‘knowledge-based’ society and it is viewed as a commodity, a personal drive or a social necessity. This thesis aims to unravel its many dimensions and the values that are ascribed to it by the teachers of Greek Model Experimental High Schools. A Model Experimental High School is a relatively new type of state school in Greece, which is highly differentiated from other schools in terms of curriculum, inter-school activities, staff and students and emerged in the Greek education system in 2011. For this reason, research on the effects of this differentiation in the aspects of Lifelong Learning is scarce. The mixed methods strategy was used in order to form a complete picture of the Lifelong Learning dimensions and the research was conducted in two parts. The first part was quantitative and aimed to categorize the elements that constitute Lifelong Learning for the teachers, the factors that encourage or discourage it and its positive and negative dimensions on a macro level as, through a questionnaire, and as a result responses were collected from the thirty-six Model Experimental High Schools in urban and semi-urban areas of Greece. The second part was qualitative and through semi-structured interviews, it explored more in-depth the issue of Lifelong Learning and the concept of vocational vitality which is related both to Lifelong Learning and a teacher’s professional life. Following the propositions of the Theory of Work Adjustment, the research revealed that through the various non-formal and informal activities that the demanding context of Model Experimental High Schools promotes, Lifelong Learning acts as a reinforcer and a means of sustaining the balance between the school and the teachers by increasing their satisfaction. Moreover, both the quantitative and the qualitative methods revealed that teachers consider Lifelong Learning firstly as a means of personal development and secondly as continuous professional development. Lifelong Learning as investment in the human capital was not found as important as the previous two. Furthermore, the vocational vitality of teachers was found to be thriving due to the importance that Lifelong Learning plays in their life a and despite the difficulties which arise from the work demands or the difficult socioeconomic context in Greece due to the economic crisis of the recent years.
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Alharbi, Basmah Fehaid H. "Young Saudi women’s beliefs upon their engagement in physical activity: A mixed method study." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/227842/1/Basmah%20Fehaid%20H_Alharbi_Thesis.pdf.
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A culturally sensitive and theory-based questionnaire, the Belief-Based Physical Activity Questionnaire for young Saudi females aged 18-35, (BPAQ-YSF) was developed, validated, and adapted to the Saudi culture. Based on the Theory of Planned Behaviour, the research identified Saudi females' physical activity beliefs, developed a valid, theory-based questionnaire for Saudi Arabic culture, and identified the psychosocial factors that influence their engagement in physical activity. An exploratory sequential mixed-methods design was used to conduct five integrated studies. This research will contribute to one of the main elements of Saudi Arabia's 2030 vision by helping Saudis adopt and maintain a more active and healthier lifestyle.
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Olesen, Terry. "Individual adaptation to discontinuous employment for Australian workers : a longitudinal mixed method study." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/522.
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This thesis research has had two aims: first, to determine how discontinuous (or “casual”) employment impacts on quality of life, mental health, and coping for a population of Australian job seekers; second, to determine how different groups of workers differ in coping style, quality of life, and mental health when dealing with discontinuous (casual, short-term) work. To address these aims a national survey was conducted of white collar, business and technical/scientific workers (N=229 at Time 1). Workers were sampled three times over the study period of nine months. The mixed method design consisted of two phases in order to capture the richness of the phenomena in question. The quantitative phase (QN) was initiated first with a tri-monthly national survey running from July 2006-until February 2007. The survey yielded information on workers’ employment conditions, job permanency, sense of resilience, and distress levels. Phase QN yielded an “overall snapshot” of worker issues and life facet coping patterns. The qualitative phase (QL) was initiated two weeks after the start of Phase QN. In this phase the investigator conducted semi-structured interviews from a subset of nine workers taken at three- month intervals. Phase QL yielded narratives of nine-month “slices of life” for these respondents, illustrating their most current work/life conflicts and the strategies and attitudes they employed to manage such conflicts. Phase QL also allowed for the uncovering of personal meanings for work-life transitions role conflicts, perceived time shortages and respondents’ personal work-life goals. Narratives, goals and personal meanings were eventually uncovered and were integrated into nine-month case trajectories. Phase QL trajectory results were then compared and integrated with the QN quantitative survey results via a process of audit trailing, data reconfiguring, member checking, and comparing of data sets. Main Findings: for the QN analysis/methods, Distress was predicted by only three Life Facet variables: number of children, permanency (security) of one’s job, and the time of year (season). The outcome variable Resilience/Coherence was predicted by only two of the variables of interest: permanency (job security) and time of year. Overall the weak QN findings could only hint at but not substantiate the patency of the Life Facets Model in explaining discontinuous work. However the Phase QL results showed the Life Facets Model to better fit the coping narratives than other models (of staged grief, active agency, drive reduction, and stress-appraisal-coping). Though some mismatches occurred across the two (QL and QN) methods, most were resolved through mixed method techniques of auditing, cross referencing and integration. Implications of the findings for future research, social welfare, and public policy were suggested.
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Thompson-Sellers, Ingrid N. "What Informs Practice and What is Valued in Corporate Instructional Design? A Mixed Methods Study." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/msit_diss/89.
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This study used a two-phased explanatory mixed-methods design to explore in-depth what factors are perceived by Instructional Design and Technology (IDT) professionals as impacting instructional design practice, how these factors are valued in the field, and what differences in perspectives exist between IDT managers and non-managers. For phase 1 of the study, one hundred and sixteen corporate IDT professionals (managers and non-managers) responded to a web-based survey that was designed and developed from: (a) The results of an exploratory study of the practices of corporate instructional designers, (b) the results of an extensive literature review into the theory and practice in the field of IDT, and (c) other survey instruments developed, validated and used in prior studies. Analysis of the data collected in phase 1 of the study resulted in the development of an Evaluation Model for IDT Practice that was used as a framework to answer the research questions. Quantitative analysis included the use of Hotelling’s T2 inferential statistic to test for mean differences between managers and non-managers perceptions of formal and informally trained groups of IDT personnel. Chi squared analysis test of independence, and correlation analysis was used to determine the nature and extent of the relationship between the type of training and the professional status of the participants. For phase 2 of the study, semi-structured interviews were conducted with selected participants and analyzed using the constant comparative method in order to help validate the findings from phase 1.
Ensuing analysis of the survey data determined that, both managers and non-managers generally agreed that both formal and on the job training was valuable, and that their peers who were formally and informally trained were competent instructional designers. The qualitative phase of the study and a closer examination of effect sizes suggested the potential for some variation in perceptions. In addition, a statistically significant correlation showed that IDT managers who completed the survey were more likely to be formally trained. Recommendations based on the results included future studies with a larger, more diverse population; future studies to refine the Evaluation Model for ID practice; and that academic ID programs work more closely with practitioners when designing and delivering their curricula.
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Bettemir, Onder Halis. "Sensitivity And Error Analysis Of A Differential Rectification Method For Ccd Frame Cameras And Pushbroom Scanners." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607708/index.pdf.
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In this thesis, sensitivity and error analysis of a differential rectification method were performed by using digital images taken by a frame camera onboard BILSAT and pushbroom scanner on ASTER. Three methods were implemented for Sensitivity and Uncertainty analysis: Monte Carlo, covariance analysis and FAST (Fourier Amplitude Sensitivity Test). A parameter estimation procedure was carried out on the basis of so called Mixed Model extended by some suitable additional regularization parameters to stabilize the solution for improper geometrical conditions of the imaging system. The effectiveness and accuracy of the differential rectification method were compared with other rectification methods and the results were analyzed. Furthermore the differential method is adapted to the pushbroom scanners and software which provides rectified images from raw satellite images was developed.
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Wallace, Ian Joseph. "Examining student engagement and its influence in a social contextual model of adolescent health behavior change." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1500.
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Current theoretical models of health behavior change frequently serve as the theoretical backdrop to adolescent health promotion programs. Yet, despite that each main theory was developed with adults and for adults, appropriate and necessary changes for adolescents are often neglected. The unique values, priorities, and abilities of adolescents are important and therefore necessary to consider during health promotion efforts. The present study explored student engagement, a unique adolescent need that has been shown to facilitate achievement in academic environments. Evidence from the psychological and educational literatures suggests that engagement may uniquely influence the process of health behavior change for adolescents. Due to the paucity of related investigations, the current study first explored the structure of the student engagement construct, and second, tested student engagement as a predictor of behavioral intentions in three separate social contextual models of adolescent health behavior change. A mixed-method quasi-experimental design was used in the investigation. Data were gathered from a school-based randomized intervention program, Building a BRIDGE to Better Health (BRIDGE). BRIDGE was a 6 week life skills intervention program that was created to promote cancer-risk reduction among adolescents. It was based on a genealogy and health promotion/disease prevention model. An exploratory factor analysis (EFA) was performed to investigate the latent structure of the student engagement construct. Linear mixed models (LMM) were used to test student engagement as a novel predictor within social contextual models of health behavior change predicting student intentions to reduce fat consumption, conduct self-examinations, and exercise. The EFA yielded a one-factor solution that included six of the initial seven items. This finding did not support the hypothesis, which predicted that items would differentiate into behavioral, cognitive, and emotional types of student engagement. Results of the LMMs supported the hypotheses that student engagement would have a significant effect on student intentions to reduce fat consumption, conduct self-examinations, and exercise. Based on comparisons between student engagement and similar predictor variables, overall findings indicate mixed support for student engagement as a significant predictor in theoretically-based models of adolescent health behavior change.
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Ismoyo, Thomas Ulun. "An exploration of calling, job performance, and innovation in the Catholic Church." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/227064/1/Thomas%20Ulun_Ismoyo_Thesis.pdf.
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This research explores the notion of work as a calling and its impact on job performance and innovation in the context of the Catholic Church. Employing the data gained from Catholic priests in Australia and Indonesia and utilising the lens of role identification and person-environment fit theory, this study revealed that priest’s calling is multidimensional and influences different dimensions of their job performance. Additionally, the results found the importance of organisational climate and living the calling as essential factors in enhancing the effect of calling on job performance. This research extends the literature of calling, job performance, and innovation.
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Rahimi, Noshad. "Developing a Mixed-Methods Method to Model Elderly Health Technology Adoption with Fuzzy Cognitive Map, and Its Application in Adoption of Remote Health Monitoring Technologies by Elderly Women." Thesis, Portland State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10840581.
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Providing healthcare to the ever-rising elderly population has become a severe challenge and a top priority. Emerging innovations in healthcare, such as remote health monitoring technologies, promise to provide a better quality of care and reduce the cost of healthcare. However, many elderly people reject healthcare innovations. This lack of adoption constitutes a big practical problem because it keeps the elderly from benefiting from technology advances. The phenomenon is even more pronounced among elderly women, who represent the majority of the elderly population.
A plethora of studies in the field of technology adoption resulted in sound, but highly generalized theories that are too parsimonious to provide practical insight into the phenomenon of elderly healthcare technology adoption (EHTA). There is a call to arms for novel approaches that facilitate the creation of models that expand technology adoption theories to the specifics of EHTA. This dissertation is a response to this call to arms, and it contributes to modeling practice in the EHTA field. It uses fuzzy cognitive mapping to design a novel mixed-methods modeling approach. Since elderly women constitute the majority of the elderly population, this dissertation treats elderly women’s health technology adoption (EWHTA) as the case-in-point.
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Watts, Kathleen Louise. "The Bethesda relational healing model and student Peer Governance Program : a mixed-method study of their effects on behavior, relationships, and climate in a Christian school /." Free full text is available to ORU patrons only; click to view, 2008. http://proquest.umi.com/pqdweb?did=1860334641&sid=1&Fmt=2&clientId=456&RQT=309&VName=PQD.
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Rodriguez, Adriana. "Stakeholder Views on Children’s Mental Health Services." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2891.
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Identification of evidence-based treatments (EBTs) has been an important development; however recently, some shortcomings of the approach have been highlighted. These complexities have led to a surge in transportability research in mental health services science with goals of identifying needed strategies to encourage the adoption of innovations. The mental health system ecological (MHSE) model is an approach necessary to assist with closing this gap effectively as it integrates mental health contexts: client-level, provider-level, intervention-specific, service delivery, organizational, and service system characteristics. The aim of this study is to use the MHSE model to examine perspectives of mental health stakeholders on their needs. Data consists of qualitative transcripts from parent, therapist, and administrator interviews/focus groups. Mixed methods were used to develop and analyze codes according to the MHSE model. Results suggested that stakeholder groups mentioned needs relevant to the group of interest and thus have implications for future dissemination efforts.
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Aussel, Lucie. "Évaluer les dispositifs : le cas d'un dispositif de formation de l'enseignement supérieur agricole." Thesis, Toulouse 2, 2013. http://www.theses.fr/2013TOU20138/document.
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L’enjeu de cette thèse est de construire un modèle d’évaluation de dispositif de formation et de le confronter à l’empirie. Nous avons mené une recherche-intervention dans le cadre d’un appel à projets, et réalisé l’évaluation d’une expérimentation sociale ayant les traits d’un dispositif de formation. Dans ce contexte de recherche commanditée, nous explicitons l’émergence d’un espace pour la recherche et l’articulation d’un volet social (à visée praxéologique) et d’un volet académique (à visée heuristique). Le modèle d’évaluation se base sur une logique de reddition des comptes, mais aussi de développement des acteurs. Il se scinde en deux orientations : connaître pour objectiver et connaître pour expliquer. La première orientation développe une approche quantitative mesurant l’efficacité du dispositif, la seconde orientation la complète et permet de l’interpréter. Elle propose une approche qualitative mesurant les évolutions cognitives des destinataires du dispositif, caractérisant les effets non escomptés et l’efficacité perçue par les acteurs. L’analyse des données a permis de consolider des éléments du modèle, de pointer des limites et de proposer des points d’appui pour contribuer à le stabiliser. Nous avons proposé l’ajout d’un volet s’intégrant à la seconde orientation connaître pour expliquer. Il porte sur l’analyse du changement dans la mise en place du dispositif. De plus, nous avons proposé cinq points d’appui : méthodologique, axiologique, heuristique, épistémologique et politique qui renforce la cohérence générale du modèle. Le modèle d’évaluation de dispositif de formation a résisté à l’empirieThe aim of this thesis is to construct a model for evaluating training programs and to check its relevance by confronting it with empirical data. We conducted this intervention-research in the framework of a call for proposals and evaluated a social experiment bearing the characteristics of a training program. Within this context of commissioned research, we explain the emergence of an area for the research and articulation of a social dimension (for praxeological purposes) and an academic dimension (for heuristic purposes). The evaluation model is based on the method of accountability but also on the development of the actors involved. It mobilizes two different methodological orientations: “acquiring knowledge to objectify” and “acquiring knowledge to interpret”. The first takes a quantitative approach and measures the efficiency of the program; the second completes the first and facilitates its interpretation. The second orientation takes a qualitative approach measuring the cognitive developments of the training beneficiaries, characterizing the unexpected effects and efficiency as perceived by the actors involved. Thanks to the data analysis, we have been able to consolidate certain elements of the model, highlight some of its limits and offer some leverage points to help stabilize it. We propose adding a component to the second orientation “acquiring knowledge to interpret”, in order to focus on the analysis of change in the implementation of the program. Likewise, we provide five methodological, axiological, heuristic, epistemological and political leverage points which strengthen the general coherence of the model. The evaluation model has withstood the confrontation with empirical data
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Pimentel, Eduardo da Cruz Gouveia. "Uso das rotações de givens modificadas como um método direto para obtenção e atualização das soluções em sistemas com acumulação seqüencial de dados /." Jaboticabal : [s.n.], 2007. http://hdl.handle.net/11449/104940.
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Resumo: O objetivo da pesquisa descrita nesta tese foi estudar possíveis aplicações do método das rotações modificadas de Givens na solução de sistemas de equações lineares tipicamente observados em problemas de melhoramento animal. Duas aplicações foram consideradas: a predição de valores genéticos com base em informação fenotípica e genealógica, por meio da metodologia dos modelos mistos; e a predição de valores genéticos com base em informação molecular, obtida pela genotipagem de painéis densos de SNPs. Na primeira aplicação, delineou-se o emprego de um modelo animal reduzido, combinado a uma ordenação do sistema que permitiu uma abordagem multi-frontal de decomposição. As matrizes frontais foram definidas como sendo as partes da triangular superior pertinentes a cada rebanho. Com isso, o problema pôde ser desmembrado em n subproblemas em que n é o número de rebanhos. Um conjunto de programas foi desenvolvido de modo a decompor as matrizes de dados de cada rebanho independentemente, e depois combinar as informações de todos eles na solução do sistema triangular geral, por retro-substituição. Concluiu-se que o método pode ser empregado em um sistema para atualização de predições de valor genético sob modelo animal reduzido, em que se aninham os efeitos de vacas dentro de rebanhos. Na segunda aplicação, comparou-se o emprego das rotações de Givens com o método do Gradiente Conjugado, na solução de sistemas lineares envolvidos na estimação de efeitos de SNPs em valores genéticos. O método das rotações demandou menos tempo de processamento e mais memória. Concluiu-se que, dado o crescente avanço em capacidade computacional, o método das rotações pode ser um método numérico viável e apresenta a vantagem de permitir o cálculo dos erros-padrão das estimativas.Abstract: The aim of this study was to investigate possible applications of the modified Givens rotations on the solution of linear systems that typically arise in animal breeding problems. Two applications were considered: prediction of breeding values based on phenotypes and relationships, using mixed model methods; and prediction of breeding values based on molecular information, using genotypes from high density SNP chips. In the first application, the use of a reduced animal model, combined with a specific ordering of the system, made it possible to apply a multi-frontal decomposition approach. The frontal matrices were defined as the parts of the upper triangular corresponding to each herd. In this way, the problem could be partitioned into n subproblems, where n is the number of herds. A set of programs was developed in order to factorize the data matrix of each herd independently, and then combine the information from all of them while solving the overall triangular system, by back-substitution. The conclusion was that Givens rotations can be used as a numerical method for updating predicted breeding values under a reduced animal model, if dam effects are nested within herds. In the second application, the modified Givens rotations were compared to the Conjugate Gradient method for solving linear systems that arise in the estimation of SNP effects on breeding values. Givens rotations required less processing time but a greater amount of high speed memory. The conclusion was that, given the increasing rate of advance in computer power, Givens rotations can be regarded as a feasible numerical method which presents the advantage that it allows for the calculation of standard errors of estimates.
Orientador: Sandra Aidar de Queiroz
Coorientador: Luiz Alberto Fries
Coorientador: Flávio Schramm Schenkel
Banca: João Meidanis
Banca: Ricardo da Fonseca
Banca: Roberto Carvalheiro
Banca: Adhemar Sanches
Doutor
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Yu, Jianxiong. "Pavement Service Life Estimation And Condition Prediction." See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2005. http://www.ohiolink.edu/etd/view.cgi?toledo1132896646.
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Dissertation (Ph.D.)--University of Toledo, 2005.Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Engineering." Bibliography: leaves 69-74.
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Pimentel, Eduardo da Cruz Gouveia [UNESP]. "Uso das rotações de givens modificadas como um método direto para obtenção e atualização das soluções em sistemas com acumulação seqüencial de dados." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/104940.
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O objetivo da pesquisa descrita nesta tese foi estudar possíveis aplicações do método das rotações modificadas de Givens na solução de sistemas de equações lineares tipicamente observados em problemas de melhoramento animal. Duas aplicações foram consideradas: a predição de valores genéticos com base em informação fenotípica e genealógica, por meio da metodologia dos modelos mistos; e a predição de valores genéticos com base em informação molecular, obtida pela genotipagem de painéis densos de SNPs. Na primeira aplicação, delineou-se o emprego de um modelo animal reduzido, combinado a uma ordenação do sistema que permitiu uma abordagem multi-frontal de decomposição. As matrizes frontais foram definidas como sendo as partes da triangular superior pertinentes a cada rebanho. Com isso, o problema pôde ser desmembrado em n subproblemas em que n é o número de rebanhos. Um conjunto de programas foi desenvolvido de modo a decompor as matrizes de dados de cada rebanho independentemente, e depois combinar as informações de todos eles na solução do sistema triangular geral, por retro-substituição. Concluiu-se que o método pode ser empregado em um sistema para atualização de predições de valor genético sob modelo animal reduzido, em que se aninham os efeitos de vacas dentro de rebanhos. Na segunda aplicação, comparou-se o emprego das rotações de Givens com o método do Gradiente Conjugado, na solução de sistemas lineares envolvidos na estimação de efeitos de SNPs em valores genéticos. O método das rotações demandou menos tempo de processamento e mais memória. Concluiu-se que, dado o crescente avanço em capacidade computacional, o método das rotações pode ser um método numérico viável e apresenta a vantagem de permitir o cálculo dos erros-padrão das estimativas.
The aim of this study was to investigate possible applications of the modified Givens rotations on the solution of linear systems that typically arise in animal breeding problems. Two applications were considered: prediction of breeding values based on phenotypes and relationships, using mixed model methods; and prediction of breeding values based on molecular information, using genotypes from high density SNP chips. In the first application, the use of a reduced animal model, combined with a specific ordering of the system, made it possible to apply a multi-frontal decomposition approach. The frontal matrices were defined as the parts of the upper triangular corresponding to each herd. In this way, the problem could be partitioned into n subproblems, where n is the number of herds. A set of programs was developed in order to factorize the data matrix of each herd independently, and then combine the information from all of them while solving the overall triangular system, by back-substitution. The conclusion was that Givens rotations can be used as a numerical method for updating predicted breeding values under a reduced animal model, if dam effects are nested within herds. In the second application, the modified Givens rotations were compared to the Conjugate Gradient method for solving linear systems that arise in the estimation of SNP effects on breeding values. Givens rotations required less processing time but a greater amount of high speed memory. The conclusion was that, given the increasing rate of advance in computer power, Givens rotations can be regarded as a feasible numerical method which presents the advantage that it allows for the calculation of standard errors of estimates.
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Sobíšek, Lukáš. "Shluková a regresní analýza mikropanelových dat." Doctoral thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-261941.
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The main purpose of panel studies is to analyze changes in values of studied variables over time. In micro panel research, a large number of elements are periodically observed within the relatively short time period of just a few years. Moreover, the number of repeated measurements is small. This dissertation deals with contemporary approaches to the regression and the clustering analysis of micro panel data. One of the approaches to the micro panel analysis is to use multivariate statistical models originally designed for crosssectional data and modify them in order to take into account the within-subject correlation. The thesis summarizes available tools for the regression analysis of micro panel data. The known and currently used linear mixed effects models for a normally distributed dependent variable are recapitulated. Besides that, new approaches for analysis of a response variable with other than normal distribution are presented. These approaches include the generalized marginal linear model, the generalized linear mixed effects model and the Bayesian modelling approach. In addition to describing the aforementioned models, the paper also includes a brief overview of their implementation in the R software. The difficulty with the regression models adjusted for micro panel data is the ambiguity of their parameters estimation. This thesis proposes a way to improve the estimations through the cluster analysis. For this reason, the thesis also contains a description of methods of the cluster analysis of micro panel data. Because supply of the methods is limited, the main goal of this paper is to devise its own two-step approach for clustering micro panel data. In the first step, the panel data are transformed into a static form using a set of proposed characteristics of dynamics. These characteristics represent different features of time course of the observed variables. In the second step, the elements are clustered by conventional spatial clustering techniques (agglomerative clustering and the C-means partitioning). The clustering is based on a dissimilarity matrix of the values of clustering variables calculated in the first step. Another goal of this paper is to find out whether the suggested procedure leads to an improvement in quality of the regression models for this type of data. By means of a simulation study, the procedure drafted herein is compared to the procedure applied in the kml package of the R software, as well as to the clustering characteristics proposed by Urso (2004). The simulation study demonstrated better results of the proposed combination of clustering variables as compared to the other combinations currently used. A corresponding script written in the R-language represents another benefit of this paper. It is available on the attached CD and it can be used for analyses of readers own micro panel data.
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Abedin, Behnam. "Social entrepreneurs value co-creation in online communities." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/231390/1/Behnam_Abedin_Thesis.pdf.
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This thesis examined how and why social entrepreneurs in Australia use online communities for value co-creation. It specifically investigated social entrepreneurs' motivations to participate in online communities, the barriers that might inhibit them from participating in online communities, and the particular abilities that they need to have in order to participate in online communities. Moreover, this study explored value co-creation activities that social entrepreneurs perform in online communities to create value together for all parties involved and the positive outcomes for them as the result of their participation in online communities.
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Iyer, Deepa Gopal. "PROPAGATION OF REQUIREMENTS ENGINEERING KNOWLEDGE IN OPEN SOURCE DEVELOPMENT: CAUSES AND EFFECTS – A SOCIAL NETWORK PERSPECTIVE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1529686228185568.
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Zhu, Xiaohong. "Numerical methods for a mixed Stokes-Darcy model /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?MATH%202007%20ZHU.
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Welham, Suzanne Jane. "Smoothing spline methods within the mixed model framework." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425673.
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Abraham, Anita Ann Edwards Lloyd J. "Model selection methods in the linear mixed model for longitudinal data." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1859.
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Thesis (DrPH)--University of North Carolina at Chapel Hill, 2008.Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Public Health in the Department of Biostatistics, School of Public Health." Discipline: Biostatistics; Department/School: Public Health.
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Lundqvist, Johanna. "Educational pathways and transitions in the early school years : Special educational needs, support provisions and inclusive education." Doctoral thesis, Stockholms universitet, Specialpedagogiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-126011.
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The overall aim of this research is to describe and analyse the educational pathways from preschool to school of a group of children with and without special educational needs. The aim is also to describe and analyse children’s views and experiences of early years education, and how these can be obtained. The research comprises six studies that are presented in four articles and two conference papers. Longitudinal and multiple-case study designs, and mixed method approaches are adopted in the empirical studies, and the data is collected via observations, a questionnaire, documents, conversations and interviews with staff, children’s drawings and interviews with children. The results from the empirical studies show a variation of pathways to compulsory education; changes in activities and relationships in the transitions; a variation in preschool quality; a broad conceptualising of special educational needs; an application of comprehensive or specialised typologies in the educational settings; an undecided and cautious attitude toward inclusive education; an allocation of generous resources to specialised and segregated programmes; and a diversity of support provisions. The children report more positive than negative experiences of their early school years and pinpoint the importance of having a sense of belonging among peers; opportunities for creative play and thinking; experiences of speed, excitement and physical challenges; elements of cosiness, withdrawals and comfort for recreation; experiences of growth in knowledge and understanding of the world; feeling safe; feeling free and autonomous; and preventing homesickness in order to thrive. The results of the literature review are that the researchers may obtain data from children with and without special educational needs by means of traditional and innovative data collection methods. For broadening participation and sharing of views, the researchers may offer relational and material support. The thesis has relevance for researchers in the field of special education, inclusive education and early childhood education and care. It has also relevance for teacher training, policy makers and stakeholders, school heads, teachers and families.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Submitted.
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Roberts, Robert E. "A study of the cognitive and affective characteristics of high and low achievers in Year 10 algebra." Thesis, Queensland University of Technology, 2003. https://eprints.qut.edu.au/36679/1/36679_Digitised%20Thesis.pdf.
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This study focused on successful performance in school algebra. It sought to determine what high achievers in Year 10 algebra knew and felt about algebra that enabled them to succeed while their peers were less successful. The study aimed to identify essential cognitive and affective variables which associate significantly with successful performance in algebra and to develop a model to explain how these variables interact to facilitate that success. Implications for instruction were then drawn and recommendations made relating to curriculum design, teacher education and further associated research.
The literature study indicated that three basic concepts, which are representation, generalisation, and functionality, appear to underlie algebraic thinking. A conceptual understanding of a subject together with a range of problem solving abilities distinguish expert from novice intellectual behaviour generally. In addition a range of affective variables including belief in the value of the task, self-concept and self-efficacy beliefs, together with attitudinal variables, impact significantly on successful performance generally.
A two-stage research design was chosen for the study, involving a gender-balanced sample of 54 Year 10 extension (top stream) mathematics students - approximately half from a state school, and the remainder from a private school - from a semi-rural area of Australia. In Stage One all subjects were given a written test of algebra attainment and a series of written tests of the identified basic concepts, that is representation, generalisation and functionality. A questionnaire survey was conducted to determine their beliefs about and attitudes towards, themselves, algebra and mathematics in general. The questionnaire also asked about classroom experiences, perceived scholastic abilities, parental, and perceived teacher and peer group influences on the subjects' learning of algebra. The data were analysed quantitatively and qualitatively and comparisons made between the responses of a group of ten high and a group of ten low achievers in algebra. In Stage Two gender and school-balanced sub-samples from the high and low achievers groups of Stage One were selected for interview. These groups participated one-on-one in a one hour audio/video recorded think-aloud mode algebra problem solving interview conducted by the researcher. The subjects articulated theirthinking procedures and feelings as they solved a range of routine to novel algebra problems. The data gathered from this interview were analysed using both quantitative and qualitative techniques and triangulated with that of Stage One.
The Stage One findings confirmed that high achievers had a significant command of the concepts identified as basic to algebraic thinking. The questionnaire data showed high achievers held positive beliefs and attitudes about algebra and about their own capabilities. These beliefs and attitudes were significantly different from those of their less successful peers. High achievers were generally positive and confident about algebra. They valued the subject for aesthetic and practical reasons. They reported enjoying algebra and believed it enhanced their general thinking and problem solving capabilities. High achievers were self-aware and held strong self-efficacy beliefs. They knew they worked hard and were respected by their teachers and peers and were supported by their parents. Subjects who were less successful in algebra also reported parental support and generally good teacher relations, but reported not being inspired by algebra and not being confident that they could succeed in the subject. No gender or school effects (private or state) were found.
The data gathered from algebra problem solving interviews conducted in Stage Two confirmed the high and low achiever ratings on the identified basic algebra concepts. This was particularly evident with generalisation and with functionality. Noticeably, however, even high achievers at this Year 10 level had difficulties with the function concept. The qualitative data analysis of the interview transcripts was aided by a grounded theory methodology which identified three stages in the algebra problem solving process, these are, information gathering, information processing and information reporting. The analysis identified eight cognitive and eight affective variables which associated significantly with successful performance in Year 10 algebra.
Based on these findings an algebra learning success model was developed. The model postulates that success in algebra results from the reciprocal interaction of positive beliefs and attitudes towards algebra, a sound knowledge of the identified basic concepts of representation, generalisation, and functionality from and the application of a range of problem solving abilities.
These abilities are developed, it is postulated, through the confidence building and optimistic experiences gained from early and sustained comprehension of and success with algebra. Implications for curriculum design and teacher education have been identified, presented and discussed, together with suggestions for further research relating to the algebra learning success model.
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Jackson, Tracey. "Applying the Multiple Constituents’ Model and Social Justice Variables to Determine the Constituents’ Perception of the Virginia Putative Father Registry." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/2974.
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A putative father registry represents a legal option for unmarried males who wish to secure legal notice regarding an adoption proceeding for a child they may have fathered. Putative father registries must balance the interests of the putative father against those of the child, the birth mother, and the adoptive parents. This study utilized a framework adapted from the Multiple Constituency Model and used social justice, as indicated by distributive justice and procedural justice, to determine the perceptions among primary constituency groups of the Virginia Putative Father Registry. This research utilized a mixed-methods approach to analyze qualitative data from focus groups in combination with quantitative results from an online survey. The results of the qualitative analysis revealed eight principal findings: First, nearly all putative fathers were unaware of the existence of putative father registry in general, or the Virginia Putative Father Registry in particular. Second, putative fathers were unaware that sex is legal notice in Virginia. Third, once aware of the concept of a putative father registry, the focus group males had positive opinions about putative father registries and the Virginia Putative Father Registry. Fourth, putative fathers preferred to receive notice through the mail regarding an alleged child. Fifth, putative fathers have a negative opinion of providing notice by posting it in newspapers. Sixth, promoting awareness of putative father registries needs to target male audiences and preferably have an interactive component. Seventh, putative fathers expressed strong positive feelings about knowing about a child they may have fathered being placed for adoption. Finally, single male participants in the focus groups were more convinced about the importance of a putative father registry in comparison to married male participants. Quantitative survey data indicated that putative fathers were perceived as the primary constituent group that would benefit the most from a putative father registry. The safeguard variable was significant as it relates to occupation, putative fathers and birth mothers. The study also found that survey respondents indicated that the general public was not aware of putative father registries, and this perception was borne out in focus group results.
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LIMA, JÚNIOR Aranildo Rodrigues de. "Modelo do voto da maioria com distribuição mista de ruído." Universidade Federal Rural de Pernambuco, 2011. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4524.
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In the majority-vote model with noise, defined in a network, a given site (spin) assumes the posite state (sign) of the majority of its neighboring spins with probability q and it takes the same state with probability (1−q). The noise parameter q is homogeneous for all sites. In this work, we investigate a more general and realistic version of the majority-vote model, in which a given site i has its own noise parameter qi satisfying a mixed probability distribution. In this way, there is a heterogeneous distribution of noise among the sites in the network. We consider the case of a distribution defined by P(qi) = bd (qi)+(1−b)d (qi−q), where b is the fraction of sites without noise and q is taken from a Gaussian distribution. We perform Monte Carlo simulations on random graphs of different sizes and three average connectivity, for several values of the parameter b. We calculate the magnetization, the susceptibility and the Binder’s fourth-order cumulant as functions of q. We note that the system presents an order-disorder phase transition at a critical value of the parameter noise qc, which is an increasing function of the fraction of sites without noise. We use finite-size scaling theory to construct the phase diagram of the model and estimate the critical exponents b /n , g / nd 1/n . These exponents satisfy the hyperscaling relation with effective dimensionality equals to unity, for all values of average connectivity and b. Finally we conclude that, the majority-vote model with mixed distribution of noise on random graphs belongs to a different universality class from the model with homogeneous distribution of noise.
No modelo do voto da maioria com ruído, definido em uma rede, um dado sítio (spin) toma o estado contrário (sinal) à maioria dos seus vizinhos com probabilidade q e concorda com o estado da maioria dos seus vizinhos com probabilidade (1−q), onde q é o parâmetro de ruído homogêneo para todos os sítios. Nessa dissertação investigamos o modelo do voto da maioria com distribuição mista de ruídos, no qual cada sítio tem o parâmetro q satisfazendo uma distribuição mista de probabilidade de forma que há uma distribuição heterogênea com relação aos ruídos dos sítios da rede. Consideramos o caso de uma distribuição dada por P(qi) = bd (qi)+(1−b)d (qi −q), onde b é a fração de sítios com ausência de ruído e q é dado por uma distribuição Gaussiana. Realizamos simulações de Monte Carlo para diversos valores do parâmetro b, em grafos aleatórios de diferentes tamanhos N e três valores da conectividade média. Calculamos a magnetização, a susceptibilidade e o cumulante de Binder como funções de q. Notamos que o sistema apresenta uma transição de fase do tipo ordem-desordem em um valor crítico do parâmetro de ruído qc, o qual é uma função crescente da fração de sítios com ausência de ruído. A partir da teoria de escala de tamanho finito construímos o diagrama de fases do modelo no plano qc versus b e estimamos os expoentes críticos b /n , g /n e 1/n . Esses expoentes satisfazem a relação de hiper-escala com a dimensionalidade efetiva do sistema D = 1 para todos os valores da conectividade média e b. Por fim concluímos que o modelo do voto da maioria com distribuição mista de ruído, pertence a uma classe de universalidade diferente do modelo com distribuição homogênea de ruído em grafos aleatórios.
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Codd, Casey. "A Review and Comparison of Models and Estimation Methods for Multivariate Longitudinal Data of Mixed Scale Type." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398686513.
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Eplett, Matthew R. "Experimental methods for the study of mixed-mode fractures." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/27552.
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Any composite material is made up from two or more materials and therefore contains interfaces, which usually represent planes of weakness. Interfacial fractures are effectively constrained to propagate along these interfaces as mixed-mode fractures with all three opening, shearing and tearing actions (i.e. mode I, mode II and mode III), instead of kinking to maintain pure-mode-I conditions at the advancing crack front, as would typically happen in an isotropic material. This is significant because mixed-mode fracture toughness is load-dependent and not a purely intrinsic material property (although clearly the pure mode fracture toughnesses are indeed intrinsic material properties that can be determined experimentally). Therefore, in order to know the fracture toughness under general loading conditions, it is necessary to know both the interface failure criterion (that describes the fracture toughness as a function of the mode mixity), and the mode mixity of the crack under the specified loading conditions. This is a complex problem that has occupied researchers in the fracture mechanics community for decades. Consequently, the literature contains a large number of different mixed-mode partition theories. This work appears to show that, of all the partition theories assessed, Wang and Harvey s (2012a) Euler beam partition theory is able to most accurately predict the fracture toughness of a mixed-mode delamination in a fibre-reinforced polymer composite laminate. This statement is based on the outcomes of three separate studies: The first study uses data reported in the literature from a thorough programme of mixed-mode fracture testing of unidirectional and multi-directional laminates. The Euler beam partition theory is able to accurately predict the fracture toughness in all cases. Furthermore, the Euler beam partition theory, which is completely analytical, closely agrees over a large domain with Davidson et al. s (2000) independently-derived non-singular field partition theory, which was derived with the aid of experimental test results. In general, the singular-field approach based on 2D elasticity and the finite element method give poor predictions. In the second study, an original programme of mixed-mode fracture testing is carried out, which incorporates several novel aspects including new test apparatus and a methodology for testing with a wide range of applied pure bending moments. Eighty five fracture tests are performed on unidirectional glass/epoxy laminates to determine the initiation and propagation fracture toughnesses. Although the second study was inconclusive with respect to the correctness of any particular partition theory, the development of the test apparatus and test methodology are considered to be major contributions that will be useful for both design engineers and academic researchers, not only working with fibre-reinforced polymer composite laminates, but also working with other composite materials containing interfacial cracks. The third study uses digital image correlation to investigate the near-crack tip strain fields of mixed-mode delaminations to try to discover the underlying mechanics that govern the selection of a mixed-mode partition theory. The new testing apparatus is used again, and another novel testing methodology is developed. The work appears to confirm (with some caveats) that two sets of pure modes exist, that is, two pure mode I modes, and two pure mode II modes, with their numerical values roughly corresponding to those from Wang and Harvey s (2012a) Euler beam partition theory. It should be noted that, as far as the author s knowledge is concerned, Euler beam partition theory is the only one in the literature to predict the existence of two sets of pure modes. Although this work set out to conclusively determine which mixed-mode partition theory is able to most accurately predict the fracture toughness of a mixed-mode delamination in a fibre-reinforced polymer composite laminate, and also, to discover why, the outcomes cannot truly be called conclusions . Rather, they only offer strong support for Wang and Harvey s (2012a) Euler beam partition theory for predicting the fracture toughness fibre-reinforced polymer composite laminates against delamination. Despite this, the work makes major contributions that will be useful for both design engineers and academic researchers in the field, as described in the above.
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Chen, Jinsong. "Semiparametric Methods for the Generalized Linear Model." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28012.
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The generalized linear model (GLM) is a popular model in many research areas. In the GLM, each outcome of the dependent variable is assumed to be generated from a particular distribution function in the exponential family. The mean of the distribution depends on the independent variables. The link function provides the relationship between the linear predictor and the mean of the distribution function. In this dissertation, two semiparametric extensions of the GLM will be developed. In the first part of this dissertation, we have proposed a new model, called a semiparametric generalized linear model with a log-concave random component (SGLM-L). In this model, the estimate of the distribution of the random component has a nonparametric form while the estimate of the systematic part has a parametric form. In the second part of this dissertation, we have proposed a model, called a generalized semiparametric single-index mixed model (GSSIMM). A nonparametric component with a single index is incorporated into the mean function in the generalized linear mixed model (GLMM) assuming that the random component is following a parametric distribution.
In the first part of this dissertation, since most of the literature on the GLM deals with the parametric random component, we relax the parametric distribution assumption for the random component of the GLM and impose a log-concave constraint on the distribution. An iterative numerical algorithm for computing the estimators in the SGLM-L is developed. We construct a log-likelihood ratio test for inference. In the second part of this dissertation, we use a single index model to generalize the GLMM to have a linear combination of covariates enter the model via a nonparametric mean function, because the linear model in the GLMM is not complex enough to capture the underlying relationship between the response and its associated covariates. The marginal likelihood is approximated using the Laplace method. A penalized quasi-likelihood approach is proposed to estimate the nonparametric function and parameters including single-index coe±cients in the GSSIMM. We estimate variance components using marginal quasi-likelihood. Asymptotic properties of the estimators are developed using a similar idea by Yu (2008). A simulation example is carried out to compare the performance of the GSSIMM with that of the GLMM. We demonstrate the advantage of my approach using a study of the association between daily air pollutants and daily mortality adjusted for temperature and wind speed in various counties of North Carolina.Ph. D.
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Frühwirth-Schnatter, Sylvia, and Thomas Otter. "Conjoint Analysis Using Mixed Effect Models." Department of Statistics and Mathematics, WU Vienna University of Economics and Business, 1999. http://epub.wu.ac.at/806/1/document.pdf.
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Following the pioneering work of Allenby and Ginter (1995) and Lenk et al.(1994); we propose in Section 2 a mixed effect model allowing for fixed and random effects as possible statistical solution to the problems mentioned above. Parameter estimation using a new, efficient variant of a Markov Chain Monte Carlo method will be discussed in Section 3 together with problems of model comparison techniques in the context of random effect models. Section 4 presents an application of the former to a brand-price trade-off study from the Austrian mineral water market. (author's abstract)Series: Forschungsberichte / Institut für Statistik
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Faure, Xavier. "Approche formelle pour la simulation interactive de modèles mixtes." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10177/document.
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La simulation interactive du corps humain est un problème crucial en informatique médicale. Les approches sont multiples pour arriver à cet objectif. Diminuer le temps de calcul est le leitmotiv d'un grand nombre de travaux ces dernières années. Pour les recherches qui utilisent des modèles physiques inspirés de la Mécanique des Milieux Continus pour la simulation des objets déformables, ce sont principalement les forces internes et leurs dérivées qui font l'objet d'études pour l'amélioration des performances au niveau du temps de calcul. Nous avons choisi de développer la Méthode des Masses-Tenseurs, modèle physique souvent utilisé pour son bon compromis temps de calcul — précision. Notre première contribution est l'utilisation du calcul formel pour la génération des équations des forces internes et de leurs dérivées. Notre deuxième contribution est la parallélisation de ce modèle physique en calculant les équations générées sur le GPU. Notre troisième contribution est l'extension de ce modèle physique à d'autres types d'éléments : triangle, quadrangle, hexaèdre, prisme et pyramide. Tenir compte des déformations pour utiliser la loi de comportement la plus efficace en temps de calcul lorsque c'est possible, est une stratégie que nous avons mis en place. Dans la même idée, nous prenons en compte la géométrie du modèle à simuler pour utiliser des éléments plus complexes mais en nombre réduit. Pour utiliser ces stratégies, nous avons développé et utilisé des modèles mixtes en loi de comportement et en type d'éléments. Nos travaux se placent dans le contexte du projet ETOILE pour le développement d'un modèle biomécanique du système respiratoireInteractive simulation of the human body is a crucial issue in medical computer sciences. There are many approaches to reach this goal. Reducing the computation time is the leitmotiv of a large number of efforts in recent years. For researches which use physical models derived from continuum mechanics for the simulation of deformable objects, it is primarily the internal forces and their derivatives which are the subject of study for improving computation time. We chose to develop the Tensor Mass Method, a physical model often used for its good computation time vs accuracy trade-off. Our first contribution is the use of computer algebra to generate the internal forces and their derivatives. Our second contribution is the parallelization of this physical model by computing the generated equations on the GPU. Our third contribution is an extension of this physical model to other elements : triangle, quandrangle , hexahedron, prism and pyramid. Considering deformations to use the most effective constitutive law in terms of computation time whenever possible is a good strategy that we started developing. In the same idea, we take the geometry of the simulated model into account to introduce more complex elements, albeit in reduced numbers. To use these strategies, we have developed mixed models in constitutive laws and elements. Our research was performed in the framework of the ETOILE project, to develop a biomechanical model of the respiratory system
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Smith, Pieter R. "A computerized search methodology for the design of mixed model assembly systems." Master's thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-02162010-020023/.
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Clewe, Oskar. "Novel Pharmacometric Methods for Informed Tuberculosis Drug Development." Doctoral thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303872.
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With approximately nine million new cases and the attributable cause of death of an estimated two millions people every year there is an urgent need for new and effective drugs and treatment regimens targeting tuberculosis. The tuberculosis drug development pathway is however not ideal, containing non-predictive model systems and unanswered questions that may increase the risk of failure during late-phase drug development. The aim of this thesis was hence to develop pharmacometric tools in order to optimize the development of new anti-tuberculosis drugs and treatment regimens. The General Pulmonary Distribution model was developed allowing for prediction of both rate and extent of distribution from plasma to pulmonary tissue. A distribution characterization that is of high importance as most current used anti-tuberculosis drugs were introduced into clinical use without considering the pharmacokinetic properties influencing drug distribution to the site of action. The developed optimized bronchoalveolar lavage sampling design provides a simplistic but informative approach to gathering of the data needed to allow for a model based characterization of both rate and extent of pulmonary distribution using as little as one sample per subject. The developed Multistate Tuberculosis Pharmacometric model provides predictions over time for a fast-, slow- and non-multiplying bacterial state with and without drug effect. The Multistate Tuberculosis Pharmacometric model was further used to quantify the in vitro growth of different strains of Mycobacterium tuberculosis and the exposure-response relationships of three first line anti-tuberculosis drugs. The General Pharmacodynamic Interaction model was successfully used to characterize the pharmacodynamic interactions of three first line anti-tuberculosis drugs, showing the possibility of distinguishing drug A’s interaction with drug B from drug B’s interaction with drug A. The successful separation of all three drugs effect on each other is a necessity for future work focusing on optimizing the selection of anti-tuberculosis combination regimens. With a focus on pharmacokinetics and pharmacodynamics, the work included in this thesis provides multiple new methods and approaches that individually, but maybe more important the combination of, has the potential to inform development of new but also to provide additional information of the existing anti-tuberculosis drugs and drug regimen.
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Johansson, Magnus, and Johan Kingstedt. "Methods for Residual Generation Using Mixed Causality in Model Based Diagnosis." Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12062.
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Several different air pollutions are produced during combustion in a diesel engine, for example nitric oxides, NOx, which can be harmful for humans. This has led to stricter emission legislations for heavy duty trucks. The law requires both lower emissions and an On-Board Diagnosis system for all manufactured heavy duty trucks. The OBD system supervises the engine in order to keep the emissions below legislation demands. The OBD system shall detect malfunctions which may lead to increased emissions. To design the OBD system an automatic model based diagnosis approach has been developed at Scania CV AB where residual generators are generated from an engine model.
The main objective of this thesis is to improve the existing methods at Scania CV AB to extract residual generators from a model in order to generate more residual generators. The focus lies on the methods to find possible residual generators given an overdetermined subsystem. This includes methods to estimate derivatives of noisy signals.
A method to use both integral and derivative causality has been developed, called mixed causality. With this method it has been shown that more residual generators can be found when designing a model based diagnosis system, which improves the fault isolation. To use mixed causality, derivatives are estimated with smoothing spline approximation.
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Hayeck, Tristan. "Retrospective Mixed Model and Propensity Score Methods for Case Control Data." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845417.
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In chapter one a Liability Threshold Mixed Linear Model (LTMLM) association statistic is introduced for ascertained case-control studies that increases power vs. existing mixed model methods for diseases with low prevalence, with a well-controlled false-positive rate. Using a chi-square score statistic computed from posterior mean liabilities (PML) under the liability threshold model. Each individual’s PML is conditional not only on that individual’s case-control status, but also on every individual’s case-control status and on the genetic relationship matrix obtained from the data estimated using a multivariate Gibbs sampler. In a Welcome Trust Case Control Consortium 2 (WTCCC2) multiple sclerosis data set LTMLM attained a 4.3% improvement (P=0.005) in chi-square statistics (vs. existing mixed model methods) at 75 known associated SNPs. Family-biased ascertainment is considered in chapter 2, where cases and controls are ascertained non-randomly with respect to family relatedness. We introduce a family based association statistic (LT-Fam) that is robust to this problem. For type 2 diabetes cases and controls (in the Jackson Heart Study) we down-sampled to increase relatedness among cases and observed: ATT was inflated and MLM was deflated, while LT-Fam was properly calibrated. Finally, in chapter three, we propose a 2-Step Bayesian Model Averaging (2-Step BMA) method with Propensity Score (PS) adjustment that targets the primary treatment of interest characterizing the treatment effect while controlling for a high dimensional set of unknown confounders including metabolites and other epidemiological factors. This method improves on existing methods by averaging over the entire model space of both the treatment and outcome models to control for cofounding while targeting treatment effect and without need of an arbitrary number of confounders to include a priori.Biostatistics
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Hapuhinna, Nelum Shyamali Sri Manik. "Bootstrap Methods for Estimation in Linear Mixed Models with Heteroscedasticity." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1626097766716384.
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Rider, Flores Marcos Julio 1975. "Planejamento da expansão de sistemas de transmissão usando os modelos CC - CA e tecnicas de programação não-linear." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260508.
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Orientador: Ariovaldo Verandio Garcia, Ruben Augusto Romero LazaroTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Neste trabalho são propostos modelos matemáticos e técnicas de solução para resolver o problema de planejamento da expansão de sistemas de transmissão através de três enfoques. a) Usando o modelo de corrente alternada do sistema de transmissão e um algoritmo heurístico construtivo especializado para resolver o problema de planejamento, e, ainda, realiza-se uma primeira tentativa de alocação de fontes de potência reativas; b) Usando o modelo de corrente contínua e técnicas de programação não-linear especializadas. Nesse caso emprega-se uma versão relaxada do problema de planejamento da expansão de sistemas de transmissão usando o modelo de corrente contínua, onde a integralidade das variáveis de investimento é desprezada. Resolve-se o problema de programação não-linear, modelado de forma matricial com um algoritmo de otimização especializado e, além disso, um algoritmo heurístico construtivo especializado é utilizado para resolver o problema de planejamento. c) Usando o modelo de corrente contínua e um algoritmo Branch and Bound (B&B) sem empregar técnicas de decomposição. Para isso foram redefinidos os chamados testes de sondagem no algoritmo B&B e em cada nó da árvore de B&B tem-se um problema de programação não-linear que são resolvidos usando a metodologia desenvolvida no item (b). Os ítens (a), (b) e (c) requerem a solução de problemas de programação não-linear diferenciados. Uma revisão das características principais da resolução iterativa dos métodos de pontos interiores é apresentada. Foi desenvolvida uma técnica baseada em uma combinação de métodos de pontos interiores de alta ordem (MPI-AO) para resolver os problemas de programação não-linear de forma rápida, eficiente e robusta. Essa combinação dos MPI-AO tem como objetivo colocar num único método as características particulares de cada um dos MPI-AO e melhorar o desempenho computacional comparado com os MPI-AO de forma individual
Abstract: In this work mathematical models and solution techniques are proposed to solve the power system transmission expansion planning problem through three approaches: a) Using the nonlinear model ofthe transmission system (AC model) and a specialized constructive heuristic algorithm to solve the problem and, yet, a first attempt to allocate reactive power sources is also considered; b) Using the direct-current (DC) model and specialized techniques of nonlinear programming. In this case a version of the power system transmission expansion planning problem using the DC model where the integrality of the investment variables is relaxed is used. The nonlinear programming problem is solved with a specialized optimization algorithm and, moreover, a constructive heuristic algorithm is employed to solve the planning problem. c) Using the DC model and Branch and Bound (B&B) algorithm without the use of decomposition techniques. The so called fathoming tests of the B&B were redefined and at each node of the tree a nonlinear programming problem is solved using the method developed in b). Items a), b) and c) require the solution of distinct problems of nonlinear programming. A revision of the main characteristics of the iterative solution of the interior points methods is presented. An optimization technique based on a combination of the higher order interior point methods (HO-IPM) had been developed to solve the nonlinear programming problems in a fast, efficient and robust way. This combination of the HO-IPM has as objective to explore the particular characteristics of each method in a single one and to improve the comparative computational performance with the HO-IPM of individual form
Doutorado
Energia Eletrica
Doutor em Engenharia Elétrica
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Quevedo, Candela Ana Valeria. "Statistical Methods for Non-Linear Profile Monitoring." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96265.
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We have seen an increased interest and extensive research in the monitoring of a process over time whose characteristics are represented mathematically in functional forms such as profiles. Most of the current techniques require all of the data for each profile to determine the state of the process. Thus, quality engineers from industrial processes such as agricultural, aquacultural, and chemical cannot make process corrections to the current profile that are essential for correcting their processes at an early stage. In addition, the focus of most of the current techniques is on the statistical significance of the parameters or features of the model instead of the practical significance, which often relates to the actual quality characteristic. The goal of this research is to provide alternatives to address these two main concerns. First, we study the use of a Shewhart type control chart to monitor within profiles, where the central line is the predictive mean profile and the control limits are formed based on the prediction band. Second, we study a statistic based on a non-linear mixed model recognizing that the model leads to correlations among the estimated parameters.Doctor of Philosophy
Checking the stability over time of the quality of a process which is best expressed by a relationship between a quality characteristic and other variables involved in the process has received increasing attention. The goal of this research is to provide alternative methods to determine the state of such a process. Both methods presented here are compared to the current methodologies. The first method will allow us to monitor a process while the data is still being collected. The second one is based on the quality characteristic of the process and takes full advantage of the model structure. Both methods seem to be more robust than the current most well-known method.
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Pantouvanos, John P. "A computerized methodology for balancing and sequencing mixed model stochastic assembly lines." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07212009-040309/.
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Nelson, Kerrie P. "Generalized linear mixed models : development and comparison of different estimation methods /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/8960.
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Chen, Mi. "Using an integrated linkage method to predict hydrological responses of a mixed land use watershed." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu.
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Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xvi, 378 p.; also includes graphics (some col.). Includes bibliographical references (p. 229-252). Available online via OhioLINK's ETD Center
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Dosne, Anne-Gaëlle. "Improved Methods for Pharmacometric Model-Based Decision-Making in Clinical Drug Development." Doctoral thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305697.
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Pharmacometric model-based analysis using nonlinear mixed-effects models (NLMEM) has to date mainly been applied to learning activities in drug development. However, such analyses can also serve as the primary analysis in confirmatory studies, which is expected to bring higher power than traditional analysis methods, among other advantages. Because of the high expertise in designing and interpreting confirmatory studies with other types of analyses and because of a number of unresolved uncertainties regarding the magnitude of potential gains and risks, pharmacometric analyses are traditionally not used as primary analysis in confirmatory trials. The aim of this thesis was to address current hurdles hampering the use of pharmacometric model-based analysis in confirmatory settings by developing strategies to increase model compliance to distributional assumptions regarding the residual error, to improve the quantification of parameter uncertainty and to enable model prespecification. A dynamic transform-both-sides approach capable of handling skewed and/or heteroscedastic residuals and a t-distribution approach allowing for symmetric heavy tails were developed and proved relevant tools to increase model compliance to distributional assumptions regarding the residual error. A diagnostic capable of assessing the appropriateness of parameter uncertainty distributions was developed, showing that currently used uncertainty methods such as bootstrap have limitations for NLMEM. A method based on sampling importance resampling (SIR) was thus proposed, which could provide parameter uncertainty in many situations where other methods fail such as with small datasets, highly nonlinear models or meta-analysis. SIR was successfully applied to predict the uncertainty in human plasma concentrations for the antibiotic colistin and its prodrug colistin methanesulfonate based on an interspecies whole-body physiologically based pharmacokinetic model. Lastly, strategies based on model-averaging were proposed to enable full model prespecification and proved to be valid alternatives to standard methodologies for studies assessing the QT prolongation potential of a drug and for phase III trials in rheumatoid arthritis. In conclusion, improved methods for handling residual error, parameter uncertainty and model uncertainty in NLMEM were successfully developed. As confirmatory trials are among the most demanding in terms of patient-participation, cost and time in drug development, allowing (some of) these trials to be analyzed with pharmacometric model-based methods will help improve the safety and efficiency of drug development.
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Oesterle, Jonathan. "Holistic approach to designing hybrid assembly lines A comparative study of Multi-Objective Algorithms for the Assembly Line Balancing and Equipment Selection Problem under consideration of Product Design Alternatives Evaluation of the influence of dominance rules for the assembly line design problem under consideration of product design alternatives Hybrid Multi-objective Optimization Method for Solving Simultaneously the line Balancing, Equipment and Buffer Sizing Problems for Hybrid Assembly Systems Comparison of Multiobjective Algorithms for the Assembly Line Balancing Design Problem Efficient multi-objective optimization method for the mixed-model-line assembly line design problem Detaillierungsgrad von Simulationsmodellen Rechnergestützte Austaktung einer Mixed-Model Line. Der Weg zur optimalen Austaktung." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0012.
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Le travail présenté dans cette thèse concerne la formulation et la résolution de deux problèmes d'optimisation multi-objectifs. Ces problèmes de décision, liés à une approche holistique, ont pour but de sélectionner la meilleure configuration « produit/ligne d’assemblage » à partir d'un ensemble de design produits, et de ressources. Concernant le premier problème, un modèle de coût a été développé afin de traduire les interdépendances complexes entre la sélection d’un design produit et les caractéristiques des ressources. Une étude empirique est proposée et vise à comparer, selon plusieurs indicateurs de qualité multi-objectifs, différentes méthodes de résolution - comprenant des algorithmes génétiques, de colonies de fourmis, d’optimisation par essaims particulaires, des chauves-souris, de recherche du coucou et de pollinisation des fleurs. Plusieurs règles de dominance et une recherche locale spécifique au problème ont été appliquées aux méthodes de résolution les plus prometteuses. Concernant le second problème, qui se penche également sur le dimensionnement des stocks tampons, les méthodes de résolution sont à un modèle de simulation à événements discrets, dont la fonction première est l’évaluation des valeurs des différentes fonctions objectives. L’approche holistique associée aux deux problèmes a été validée avec deux cas industrielsThe work presented in this thesis concerns the formulation and the resolution of two holistic multi-objective optimization problems associated with the selection of the best product and hybrid assembly line configuration out of a set of products, processes and resources alternatives. Regarding the first problem, a cost model was developed in order to translate the complex interdependencies between the selection of specific product designs, processes and resources characteristics. An empirical study is proposed, which aimed at comparing, according to several multi-objective quality indicators, various resolution methods – including variants of evolutionary algorithms, ant colony optimization, particle swarm optimization, bat algorithms, cuckoo search algorithms, and flower-pollination algorithms. Several dominance rules and a problem-specific local search were applied to the most promising resolution methods. Regarding the second problem, which also considers the buffer sizing, the developed algorithms were enhanced with a genetic discrete-event simulation model, whose primary function is to evaluate the value of the various objective functions. The demonstration of the associated resolution frameworks for both problems was validated through two industrial-cases
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Karlsson, Elisabeth. "Ungdomars attityder till oral hälsa och upplevelse av att ha fått ta del av en beteendevetenskaplig intervention samt dess effekt på munhygienbeteende." Thesis, Hälsohögskolan, Högskolan i Jönköping, HHJ. Oral hälsa, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-36555.
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Syfte: Pröva en integrerad metod av den transteoretiska modellen och begreppet känsla av sammanhang hos ungdomar gällande munhygienbeteende och upplevelse av intervention och reflektioner kring oral hälsa. Metod: Studien utfördes med en mixad metod. Urvalet bestod av 20 ungdomar där 11 valde att delta. Deltagarna randomiserades till två grupper där experimentgrupp vid base-line fick ta del av den beteendevetenskapliga interventionen och kontrollgrupp av en mer traditionell tandvårdsbehandling. Plack och gingivit mättes vid base-line och efter en månad. Experimentgrupp intervjuades vid uppföljning om upplevelse av att ha fått ta del av intervention och inställningar till oral hälsa. Statistiska analyser av kvantitativa data gjordes för att räkna ut skillnader inom respektive grupper samt mellan dem gällande plack och gingivit. Dataanalysen utfördes med deskriptiv statistik och icke-parametriska test. En kvalitativ innehållsanalys gjordes av intervjuerna och sedan jämfördes kvantitativa och kvalitativa resultat och presenterades i en metaslutsats. Resultat: Mellan base-line och en-månads uppföljning minskade plack och gingivit signifikant hos experimentgruppen. I jämförelse mellan grupperna minskade plack och gingivit mer hos experimentgrupp än kontrollgrupp. Frågeställningen kring deltagarnas upplevelse av interventionen resulterade i huvudkategorierna ”positivt bemötande” och ”begriplig och motiverande kunskap”, med fyra underkategorier. Frågeställningen om reflektioner kring oral hälsa resulterade i ”oral hälsa ur en social kontext” och ”munnens betydelse för att fungera och se bra ut” också med fyra underkategorier. Slutsats: Den integrerade beteendevetenskapliga interventionen gav ett bättre resultat på munhygienbeteende hos deltagarna än den mer traditionella tandvårdsbehandlingen. Upplevelsen av att ha tagit del av interventionen var positiv vilket stärker interventionens användbarhet. Mer forskning behövs för att utreda nyttan och användbarheten av interventionen inom tandvården.
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Golden, Bethannie L. "Risk Perception for Developing Diabetes in a Population with Prediabetes: A mixed methods exploration." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523968800263111.
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Bredström, David. "Models and solution methods for large-scale industrial mixed integer programming problems /." Linköping : Division of Optimization, Department of Mathematics, Linköpings universitet, 2007. http://www.bibl.liu.se/liupubl/disp/disp2007/tek1071s.pdf.
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Espinosa, William Robert. "Collaborative Strategic Planning: A Mixed Methods Study of Models and Superintendents’ Perspectives." Digital Commons at Loyola Marymount University and Loyola Law School, 2009. https://digitalcommons.lmu.edu/etd/255.
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School district leaders use strategic planning as a tool for leading their complex education systems. They may be mandated to prepare a strategic plan or they may elect to use the strategic planning process to adapt, focus, and align their education system to improve student achievement. The challenge comes in the confusion around what constitutes an effective strategic planning model. Using models from other sectors such as business are often unsuccessful when they are modified to deal with the diversity of stakeholders, multi-discipline systems, and complexity unique to school district systems. The purpose of this study was to research the practice of using strategic planning in 269 U. S. school districts. A survey using a nine-step strategic planning model as a conceptual framework was designed to determine the use, nonuse, and prevalence of the steps. A content analysis of 78 school district strategic plan documents and the semi-structured interviews of six district superintendents provided qualitative data and narrative to the analysis. The analysis of the data from this mixed methods approach provided insights into strategic planning models in use in school districts and a perspective of their effectiveness from the point-of-view of the superintendent.
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Evangelou, Evangelos A. Smith Richard L. "Bayesian and frequentist methods for approximate inference in generalized linear mixed models." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2607.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.Title from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Statistics and Operations Research Statistics." Discipline: Statistics and Operations Research; Department/School: Statistics and Operations Research.
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Dormuth, Darryl W. "Performance assessment of mixed methods for time integration using an assembly-type queueing model." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq23596.pdf.
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