Spelling suggestions: "subject:"nested logic""
21 |
Função da probabilidade da seleção do recurso (RSPF) na seleção de habitat usando modelos de escolha discreta / Resource of selection probability function (RSPF ) the habitat selection using discrete choice models (DCM)Sandra Vergara Cardozo 16 February 2009 (has links)
Em ecologia, o comportamento dos animais é freqüentemente estudado para entender melhor suas preferências por diferentes tipos de alimento e habitat. O presente trabalho esta relacionado a este tópico, dividindo-se em três capítulos. O primeiro capitulo refere-se à estimação da função da probabilidade da seleção de recurso (RSPF) comparado com um modelo de escolha discreta (DCM) com uma escolha, usando as estatísticas qui-quadrado para obter as estimativas. As melhores estimativas foram obtidas pelo método DCM com uma escolha. No entanto, os animais não fazem a sua seleção baseados apenas em uma escolha. Com RSPF, as estimativas de máxima verossimilhança, usadas pela regressão logística ainda não atingiram os objetivos, já que os animais têm mais de uma escolha. R e o software Minitab e a linguagem de programação Fortran foram usados para obter os resultados deste capítulo. No segundo capítulo discutimos mais a verossimilhança do primeiro capítulo. Uma nova verossimilhança para a RSPF é apresentada, a qual considera as unidades usadas e não usadas, e métodos de bootstrapping paramétrico e não paramétrico são usados para estudar o viés e a variância dos estimadores dos parâmetros, usando o programa FORTRAN para obter os resultados. No terceiro capítulo, a nova verossimilhança apresentada no capítulo 2 é usada com um modelo de escolha discreta, para resolver parte do problema apresentado no primeiro capítulo. A estrutura de encaixe é proposta para modelar a seleção de habitat de 28 corujas manchadas (Strix occidentalis), assim como a uma generalização do modelo logit encaixado, usando a maximização da utilidade aleatória e a RSPF aleatória. Métodos de otimização numérica, e o sistema computacional SAS, são usados para estimar os parâmetros de estrutura de encaixe. / In ecology, the behavior of animals is often studied to better understand their preferences for different types of habitat and food. The present work is concerned with this topic. It is divided into three chapters. The first concerns the estimation of a resource selection probability function (RSPF) compared with a discrete choice model (DCM) using chi-squared to obtain estimates. The best estimates were obtained by the DCM method. Nevertheless, animals were not selected based on choice alone. With RSPF, the maximum likelihood estimates used with the logistic regression still did not reach the objectives, since the animals have more than one choice. R and Minitab software and the FORTRAN programming language were used for the computations in this chapter. The second chapter discusses further the likelihood presented in the first chapter. A new likelihood for a RSPF is presented, which takes into account the units used and not used, and parametric and non-parametric bootstrapping are employed to study the bias and variance of parameter estimators, using a FORTRAN program for the calculations. In the third chapter, the new likelihood presented in chapter 2, with a discrete choice model is used to resolve a part of the problem presented in the first chapter. A nested structure is proposed for modelling selection by 28 spotted owls (Strix occidentalis) as well as a generalized nested logit model using random utility maximization and a random RSPF. Numerical optimization methods and the SAS system were employed to estimate the nested structural parameters.
|
22 |
Quatre essais en Economie de l'Environnement empirique / Four Essays in Empirical Environmental EconomicsPoirier, Julie 11 January 2013 (has links)
Cette thèse s'articule autour de deux thèmes : l'évaluation monétaire des biens environnementaux et l'innovation en environnement. Si ces deux volets sont traités séparément, ils s'attachent toutefois à contribuer à un objectif commun : la lutte contre le changement climatique. Cette thèse se décline en cinq chapitres. Le premier propose une introduction générale, qui présente les deux thèmes développés, ainsi que leur contribution au défi du changement climatique. En attribuant une valeur pécuniaire aux biens environnementaux, l'évaluation monétaire peut servir la décision publique, non seulement lors de la mise en œuvre de projets pro-environnementaux, mais aussi en aidant é évaluer les dommages causés à l'environnement. L'innovation environnementale peut encourager les transferts de technologies et une croissance plus verte, dans une volonté de développement durable. Les chapitres 2 et 3 s'intéressent aux expériences de choix, en vue d'évaluer le consentement-à-payer pour l'amélioration de la qualité de l'eau de rivières. A partir d'une enquête proposant aux résidents de choisir entre différentes options de gestion pour les rivières de leur voisinage, nous montrons dans le chapitre 2 que ces derniers sont disposés à payer pour une meilleure qualité de l'eau. Nous nous apercevons toutefois que plus de 20% des individus de notre échantillon adoptent un comportement de protestation, c'est-à-dire déclarent un consentement-à-payer nul alors même que leur valeur pour l'eau des rivières est positive. Dans le chapitre 3, nous recourons à un modèle logit emboîté, afin de prendre en compte ce type de comportement. Nous obtenons des consentements-à-payer plus élevés, signe que le modèle utilisé est mieux adapté pour traiter des données comportant des zéros de protestation. Les chapitres 4 et 5 étudient les déterminants de l'innovation en environnement. A partir de données sur les dépôts de brevets et de l'enquête d'opinion du forum économique mondial, le chapitre 4 s'intéresse à l'impact de politiques publiques sur l'innovation en matière de technologies propres dans les domaines de l'eau, de l'air et des déchets. Notre analyse met en évidence le rôle positif sur l'innovation en environnement de la capacité d'innovation globale d'un pays et de la rigueur de ses politiques environnementales. Le chapitre 5 étudie l'influence des collaborations pour la publication d'articles scientifiques sur l'innovation en matière d'énergie éolienne. Nous couplons notre base de données sur les brevets avec une base rassemblant de nombreuses références littéraires dans le domaine de la recherche scientifique. Nous montrons que les transferts de connaissance entre les pays membres et non membres de l'OCDE dans le domaine éolien contribuent à améliorer la capacité d'innovation des pays non membres de l'OCDE. / This dissertation is interested in two areas of the environmental economics field: monetary valuation of environmental goods and services and environmental innovation. Even if those two fields are studied separately in this dissertation, they both aim at contributing to a common objective: fight against climate change. This dissertation ranges into five chapters. The first one is a general introduction, which depicts the two fields of the dissertation and their relevance towards climate change. Environmental valuation serves public decision through monetary valuation of environmental goods. This is useful not only for the implementation of projects directed to environmental protection, but also for the quantification of environmental damages. Environmental innovation may encourage technological transfers, but also a greener growth, in a will that our societies develop themselves following a sustainable path. Chapters 2 and 3 are interested in the choice experiments method in order to value local residents’ willingness-to-pay for water quality improvements at a specific river basin in France. Using a choice experiment with different management regimes for the river basin, we find that residents are willing-to-pay for an improved water quality. Despite this positive result, we observe a significant proportion (20%) of protest bids in our sample. Protest bids are respondents that state a zero willingness-to-pay, even though their true value for the good is positive. In order to take into account the existence of protest bids, we estimate a cross-nested logit model in chapter 3. We then obtain larger willingness-to-pay, which proves that the cross-nested logit model best fits the peculiarity of our data. Chapters 4 and 5 try to identify the drivers of environmental innovation. Using world patent data and data from the world economic forum survey, we study the impact of environmental public policies on innovation in clean technologies directed to water and air pollution, and waste. We find that both general innovative capacity and environmental policy stringency have a positive role on environment-related innovation. Chapter 5 looks at the influence of co-authorship of scientific publications on wind energy-related innovation. We use both the world patent database and the “Scopus” database, which contains lots of scientific literature references. We highlight the existence of knowledge spillovers between OECD and NON-OECD countries. Therefore, we show that knowledge transfers, regarding wind energy-related innovation, between OECD and NON-OECD countries contribute to improve NON-OECD countries' innovative capacity.
|
Page generated in 0.0585 seconds