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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Utilisation de splines monotones afin de condenser des tables de mortalité dans un contexte bayésien

Patenaude, Valérie 04 1900 (has links)
Dans ce mémoire, nous cherchons à modéliser des tables à deux entrées monotones en lignes et/ou en colonnes, pour une éventuelle application sur les tables de mortalité. Nous adoptons une approche bayésienne non paramétrique et représentons la forme fonctionnelle des données par splines bidimensionnelles. L’objectif consiste à condenser une table de mortalité, c’est-à-dire de réduire l’espace d’entreposage de la table en minimisant la perte d’information. De même, nous désirons étudier le temps nécessaire pour reconstituer la table. L’approximation doit conserver les mêmes propriétés que la table de référence, en particulier la monotonie des données. Nous travaillons avec une base de fonctions splines monotones afin d’imposer plus facilement la monotonie au modèle. En effet, la structure flexible des splines et leurs dérivées faciles à manipuler favorisent l’imposition de contraintes sur le modèle désiré. Après un rappel sur la modélisation unidimensionnelle de fonctions monotones, nous généralisons l’approche au cas bidimensionnel. Nous décrivons l’intégration des contraintes de monotonie dans le modèle a priori sous l’approche hiérarchique bayésienne. Ensuite, nous indiquons comment obtenir un estimateur a posteriori à l’aide des méthodes de Monte Carlo par chaînes de Markov. Finalement, nous étudions le comportement de notre estimateur en modélisant une table de la loi normale ainsi qu’une table t de distribution de Student. L’estimation de nos données d’intérêt, soit la table de mortalité, s’ensuit afin d’évaluer l’amélioration de leur accessibilité. / This master’s thesis is about the estimation of bivariate tables which are monotone within the rows and/or the columns, with a special interest in the approximation of life tables. This problem is approached through a nonparametric Bayesian regression model, in particular linear combinations of regression splines. By condensing a life table, our goal is to reduce its storage space without losing the entries’ accuracy. We will also study the reconstruction time of the table with our estimators. The properties of the reference table, specifically its monotonicity, must be preserved in the estimation. We are working with a monotone spline basis since splines are flexible and their derivatives can easily be manipulated. Those properties enable the imposition of constraints of monotonicity on our model. A brief review on univariate approximations of monotone functions is then extended to bivariate estimations. We use hierarchical Bayesian modeling to include the constraints in the prior distributions. We then explain the Markov chain Monte Carlo algorithm to obtain a posterior estimator. Finally, we study the estimator’s behaviour by applying our model on the Standard Normal table and the Student’s t table. We estimate our data of interest, the life table, to establish the improvement in data accessibility.
22

O efeito da eliminação de doenças crônicas na população idosa: a compressão e a expansão da morbidade / The effect of the elimination of chronic diseases in the elderly, the compression and expansion of the morbidity

Alessandro Gonçalves Campolina 05 March 2012 (has links)
Introdução: No contexto do envelhecimento populacional, uma questão fundamental é avaliar se as estratégias de prevenção de doenças crônicas poderiam contribuir para o aumento dos anos vividos em boas condições de saúde, pela população idosa. Objetivo: Avaliar se a eliminação de determinadas doenças crônicas é capaz de levar à compressão da morbidade em indivíduos idosos. Métodos: Estudo transversal analítico, de base populacional, utilizando dados oficiais secundários para o Município de São Paulo, em 2000, e dados obtidos a partir do estudo SABE. O método de Sullivan foi utilizado para o cálculo de expectativas de vida livre de incapacidade (E.V.L.I.). O impacto da eliminação de uma doença na prevalência de incapacidade foi estimado com um modelo de regressão logística múltipla. Tábuas de vida de eliminação de causas foram utilizadas para calcular as probabilidades de morte com a eliminação de doenças. O efeito da eliminação das doenças crônicas foi avaliado, considerando a teoria de riscos competitivos e a abordagem proposta por Nusselder e colaboradores. Resultados: Os maiores ganhos em E.V.L.I., com a eliminação de doenças crônicas, ocorreram no sexo feminino, levando a um processo de compressão absoluta da morbidade. Nos indivíduos de idade mais avançada, os ganhos em E.V.L.I., ocorreram em função de um processo de compressão relativa da morbidade. Nos homens com idade de 75 anos, todas as doenças estudadas, com exceção da doença cardíaca e da hipertensão arterial sistêmica, levaram a um processo de expansão absoluta da morbidade, mas simultaneamente a um processo de compressão relativa da morbidade, ao serem eliminadas. A doença cardíaca apresentou-se como aquela que mais promoveria a compressão da morbidade, caso fosse eliminada, em ambos os sexos. Conclusão: A eliminação de doenças crônicas na população idosa poderia levar a uma compressão da morbidade em homens e mulheres, tanto na idade de 60 anos, quanto na de 75 anos / Introduction: In the context of the aging process, a key issue is to assess whether strategies to prevent chronic diseases may contribute to the increase in years lived in good health among elderly individuals. Objective: To evaluate whether elimination of certain chronic diseases can lead to the compression of morbidity, in the elderly. Methods: Analytical cross-sectional survey, based on official data for the city of São Paulo, in 2000, and data obtained from the SABE study. Sullivans method was used for the calculation of disability-free life expectancy (DFLE). Cause-deleted disability prevalence was estimated using multiple logistic regression model. Cause-deleted probabilities of dying were derived with the cause-elimination life-table technique, considering the independence of the causes of based on the approach proposed by Nusselder and co-workers. Results: The greatest gains in DFLE, with the elimination of chronic diseases, occurred in women, leading to a process of absolute compression of morbidity. Among individuals of a more advanced age, gains in DFLE occurred due to a relative compression of morbidity process. Among men aged 75 years, all diseases eliminated, except heart disease and hypertension, led to a process of absolute expansion of morbidity, but simultaneously, to a relative compression of morbidity. If eliminated, heart disease was the condition that would most lead to the compression of morbidity in both genders. Conclusion: The elimination of chronic diseases in the elderly population could lead to the compression of morbidity in men and women at both 60 years of age and in 75 years of age or older
23

Statistické metody v demografickém prognózování / Statistical methods in demographic forecasting

Šimpach, Ondřej January 2013 (has links)
Dissertation thesis creates a complex and modern scheme for stochastic modeling of demographic processes, which is universally applicable to any population in the world. All calculations are described in detail on the data of the Czech Republic. Throughout the work the attention is drawn to the issues, that every analyst must necessarily take into account in order to obtain correct results. Data comes mostly from the Czech Statistical Office database. However, some data matrices had to be calculated for the purposes of the thesis. Particular demographic processes (mortality, fertility and migration) are modeled using selected modern approaches (ARIMA models, Lee-Carter method) and based on the constructed models these processes are forecasted to the future. Using partially projected results a comprehensive demographic projection of the population of the Czech Republic is created up to the year 2050. However, not on the basis of the current state and expert expectations of the future development, but based on sophistically projected demographic events, which are explained using the trends and main components of their previous development. This demographic projection is created in three scenarios (marked SC1, SC2 and SC3), which are made from selected optimal models, presented in particular sections of the work. One part of the thesis is also the backward retropolation of age-specific number of net migrants by sex in the Czech Republic since 1948. On its basis the analysis and prediction of the migration can be done. The thesis is a synthesis of the projections of demographic processess of mortality, fertility, and migration. Final results are confronted with three scenarios of population projections of the Czech Republic created by the Czech Statistical Office and five scenarios of population projections by Eurostat. The purely statistical approach of demographic forecasting in comparison with deterministic models and expert expectations has its positives and negatives. Therefore, the different results due to various methodological approaches are discussed and compared in the conclusion of the thesis.
24

Aplikace (geo)demografických metod v oblasti vzdělávání / Application of (geo)demographic methods in education

Šebestík, Libor January 2011 (has links)
Application of (geo)demographic methods in education Abstract This master's thesis presents the possibilities of application of demographic, geodemographic and statistical methods on data published by the educational sector. The methods of demographic analysis are represented by the usage of rates, the concept of multistate demography (Markov chains) and the application of life tables. The enrollment ratio at particular levels of education, the average length of schooling and the number of dropouts from school grades are evaluated by these procedures. Markov chains which are based on the probabilities of transition between grades are also examined in terms of their use for forecasting purposes. These methods analyze the situation at the preschool, primary and secondary levels and are used on data from the annual Statistical Yearbooks on Education. In the field of geodemography, the so called preferential model of migration flows is presented. This model examines how applicants for tertiary education prefer or reject the regions of the Czech Republic for their tertiary education studies. The last method is the binary logistic regression which analyzes the inequalities in access to tertiary education. Both preferential model and logistic regression are based on data files on the admission process at...
25

Population ecology of the red admiral butterfly (Bassaris gonerilla) and the effects of non-target parasitism by Pteromalus puparum

Barron, M. C. January 2004 (has links)
There is anecdotal evidence that populations of the New Zealand endemic red admiral butterfly Bassaris gonerilla (F.) have declined since the early 1900s. This decline has been associated with the introduction of the generalist pupal parasitoids Pteromalus puparum (L.) and Echthromorpha intricatoria (F.). The former was deliberately introduced for the biological control of the cabbage white butterfly (Pieris rapae (L.)); the latter is an adventitious arrival from Australia. The objective of this thesis was to quantify, using population models, the effect that P. puparum is having on B. gonerilla abundance. Population monitoring and a phenology model (based on temperature-related development rates) indicated that B. gonerilla has two full generations and one partial generation per summer in the Banks Peninsula region of New Zealand. B. gonerilla abundance was greatly reduced in drought summers, which was probably due to the negative effects of drought on the quality and quantity of the larval host plant Urtica ferox Forst. A life table study showed that egg parasitism by the unidentified scelionid Telenomus sp. was the largest mortality factor for the pre-imaginal stages of B. gonerilla, followed by "disappearance" mortality (predation and dispersal) in the larval stages. Pupal mortality due to P. puparum was lower compared with that caused by E. intricatoria, with 1-19% and 20-30% of pupae being parasitised by P. puparum and E. intricatoria, respectively. Collection of B. gonerilla pupae from the Christchurch, Dunedin and Wellington areas confirmed higher rates of percentage parasitism by E. intricatoria. B. gonerilla collected from the Banks Peninsula had a 50: 50 sex ratio and lifetime fecundity was estimated in the laboratory as 312 eggs per female. There was no evidence of density-dependent parasitism of B. gonerilla pupae by P. puparum in the field, although there was a significant positive relationship between life table estimates of E. intricatoria parasitism and B. gonerilla pupal abundance. Larval dispersal from the host plant showed a positive relationship with larval instar but no relationship with larval density. Rates of change in B. gonerilla adult abundance between generations within a year showed evidence of density dependence, and this negative feedback was stronger in a drought year. A discrete-time model for B. gonerilla population dynamics was constructed which had two summer generations per year and a partial overwintering generation. The model showed that the presence of this overwintering generation provides a temporal refuge from high levels of E. intricatoria parasitism. Removal of parasitoid mortality from the model suggested that P. puparum was suppressing B. Gonerilla populations on the Banks Peninsula by 5% and E. intricatoria by 30%. An important assumption of the model was that parasitism rates were independent of B. gonerilla density. This assumption appears valid for P. puparum parasitism, but may not be valid for E. intricatoria; therefore the estimated suppression levels due to this adventive parasitoid should be viewed with some caution. It is too soon to generalise on what determines the magnitude of non-target effects by arthropod biocontrol agents, this being only the second study to quantify effects at a population level. However, in this case retrospective analysis has shown that the impact of non-target parasitism by P. puparum on B. gonerilla abundance has been small. There is anecdotal evidence that populations of the New Zealand endemic red admiral butterfly Bassaris gonerilla (F.) have declined since the early 1900s. This decline has been associated with the introduction of the generalist pupal parasitoids Pteromalus puparum (L.) and Echthromorpha intricatoria (F.). The former was deliberately introduced for the biological control of the cabbage white butterfly (Pieris rapae (L.)); the latter is an adventitious arrival from Australia. The objective of this thesis was to quantify, using population models, the effect that P. puparum is having on B. gonerilla abundance. Population monitoring and a phenology model (based on temperature-related development rates) indicated that B. gonerilla has two full generations and one partial generation per summer in the Banks Peninsula region of New Zealand. B. gonerilla abundance was greatly reduced in drought summers, which was probably due to the negative effects of drought on the quality and quantity of the larval host plant Urtica ferox Forst.. A life table study showed that egg parasitism by the unidentified scelionid Telenomus sp. was the largest mortality factor for the pre-imaginal stages of B. gonerilla, followed by "disappearance" mortality (predation and dispersal) in the larval stages. Pupal mortality due to P. puparum was lower compared with that caused by E. intricatoria, with 1-19% and 20-30% of pupae being parasitised by P. puparum and E. intricatoria, respectively. Collection of B. gonerilla pupae from the Christchurch, Dunedin and Wellington areas confirmed higher rates of percentage parasitism by E. intricatoria. B. gonerilla collected from the Banks Peninsula had a 50: 50 sex ratio and lifetime fecundity was estimated in the laboratory as 312 eggs per female. There was no evidence of density-dependent parasitism of B. gonerilla pupae by P. puparum in the field, although there was a significant positive relationship between life table estimates of E. intricatoria parasitism and B. gonerilla pupal abundance. Larval dispersal from the host plant showed a positive relationship with larval instar but no relationship with larval density. Rates of change in B. gonerilla adult abundance between generations within a year showed evidence of density dependence, and this negative feedback was stronger in a drought year. A discrete-time model for B. gonerilla population dynamics was constructed which had two summer generations per year and a partial overwintering generation. The model showed that the presence of this overwintering generation provides a temporal refuge from high levels of E. intricatoria parasitism. Removal of parasitoid mortality from the model suggested that P. puparum was suppressing B. Gonerilla populations on the Banks Peninsula by 5% and E. intricatoria by 30%. An important assumption of the model was that parasitism rates were independent of B. gonerilla density. This assumption appears valid for P. puparum parasitism, but may not be valid for E. intricatoria; therefore the estimated suppression levels due to this adventive parasitoid should be viewed with some caution. It is too soon to generalise on what determines the magnitude of non-target effects by arthropod biocontrol agents, this being only the second study to quantify effects at a population level. However, in this case retrospective analysis has shown that the impact of non-target parasitism by P. puparum on B. gonerilla abundance has been small.

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