Estimation of the covariance matrix of asset returns is a key component of portfolio optimization. Inherent in any estimation technique is the capacity to inaccurately reflect current market conditions. Typical of Markowitz portfolio optimization theory, which we use as the basis for our analysis, is to assume that asset returns are stationary. This assumption inevitably causes an optimized portfolio to fail during a market crash since estimates of covariance matrices of asset returns no longer re ect current conditions. We use the market crash of 2008 to exemplify this fact. A current industry standard benchmark for estimation is the Ledoit covariance matrix, which attempts to adjust a portfolio's aggressiveness during varying market conditions. We test this technique against the CALM (Covariance Adjustment for Liability Management Method), which incorporates forward-looking signals for market volatility to reduce portfolio variance, and assess under certain criteria how well each model performs during recent market crash. We show that CALM should be preferred against the sample convariance matrix and Ledoit covariance matrix under some reasonable weight constraints.

L’intérêt principal de la thèse est le comportement mécanique à long terme des enceintes de confinement des centrales nucléaires françaises. Les enceintes de confinements des centrales sont des structures en béton précontrainte biaxiale. Nous résumons donc le problème que nous nous adressons en deux points clés : la biaxialité du chargement et les déformations différées à long terme.Afin de caractériser les déformations différées sous chargement biaxial, nous nous concentrons dans un premier temps au coefficient du Poisson viscoélastique du béton. Dans ce but, nous commençons par examiner minutieusement la définition du coefficient de Poisson dans le cadre de la viscoélasticité linéaire isotrope non-vieillissente. Puis, en analysant les résultats expérimentaux de la littérature, nous obtenons le coefficient de Poisson viscoélastique du béton. Comme extension, nous amenons une analyse micromécanique et essayons d’éclaircir le mécanisme du fluage à long terme du gel de C-S-H.Dans un deuxième temps, nous visons à proposer un modèle poroviscoélastique sans supposer préalablement la décomposition classique des déformations différées. Nous commençons par identifier les tendances expérimentales majeures et phénomènes physiques que nous voulons capturer par le modèle. À partir des résultats expérimentaux du retrait endogène et du fluage propre de la littérature, nous analysons l’origine physique possible du retrait endogène à long terme. À la fin, dérivé de la théorie de la poromécanique, un modèle poroviscoélastique basé sur la physique est proposé. La prédiction du modèle est comparée avec les résultats expérimentaux de la littérature / The main interest of the thesis is the long-term mechanical behavior of the containment building of french nuclear power plants. The containment buildings of the power plants are biaxially prestressed concrete structures. Therefore, we summarize the problem of interest into two following key points: biaxiality of load and long-term delayed strain.In order to characterize the delayed strain under biaxial load, our study first concentrates on the viscoelastic Poisson's ratio of concrete. In this purpose, we start by scrutinizing the definition of Poisson's ratio in non-aging linear isotropic viscoelasticity. Then, from the analysis of experimental results from the literature, we can obtain the viscoelastic Poisson's ratio of concrete. As an extension, we use micromechanics to shed some light on the long-term creep mechanism of the C-S-H gel.In a second step, we aim at proposing a poroviscoelastic model without postulating a priori the classical decomposition of delayed strains. We start by identifying the major experimental tendencies and physical phenomena that we aim at capturing with the model. From experimental data of autogenous shrinkage and basic creep from the literature, we analyze the possible physical origin of long-term autogenous shrinkage. In the end, a physics-based poroviscoelastic model is proposed, derived from the poromechanics theory. The prediction of the model is compared with experimental results from literature

Foram realizados estudos das ações e suas combinações, que possam ocorrer nas pontes; também foram apresentados as principais características das pontes em vigas mistas e os tabuleiros utilizados, os conectores de cisalhamento que são utilizados na ligação aço/concreto e os efeitos da retração e fluência das vigas mistas. No estudo desses efeitos realizou-se uma análise elástica; a seção transversal foi considerada idealizada e as tensões atuantes na seção mista foram obtidas através do método das tensões admissíveis. Este procedimento foi baseado por Djuric (1963) posteriormente por Mason (1976), considerando interação completa entre aço/concreto e o carregamento sendo aplicado no tempo t=0 e no tempo t='infinito'. Verificou-se ao longo do tempo um aumento do deslocamento e uma redistribuição de tensões na seção mista devido os efeitos da retração e fluência / It was achieved studies of the actions and it’s combinations that can happen at the bridges also it was presented the main characteristics of the bridges in composite beams and the slab applied the shear connectors that are utilized at the joining steel/concrete and the effects of the shrinkage and creep of the composite beams. In the study these effects come about an analysis elastic the cross-section was considered idealized and the stresses that actuate at the composite section were obtained through the method admissible stresses. This procedure was based by Djuric (1963) later by Mason (1976) considering full interaction between steel/concrete and the load being applied at the time t=0 and at the time t='infinite'. It was verified along the time a rise of the deflection and a redistribution of the stresses at the composite section due to the effects of the shrinkage and creep

O objetivo desse estudo foi avaliar a influência da técnica incremental na força coesiva de diferentes resinas compostas. Foi confeccionado para este trabalho um dispositivo bipartido de Teflon que se encaixa em um magazine metálico para manter as metades em posição durante a preparação dos corpos de prova do compósito. A partir deste dispositivo de forma cônica, e dimensões: 4mm de base, 2mm de diâmetro na interface e 4mm de altura, foram obtidos 120 espécimes, divididos em 12 grupos ( n=10), 6 grupos sem o uso de adesivo e 6 grupos com o uso de adesivo. Foram utilizadas as resinas compostas: Filtek P90-3M ESPE, St.Paul,MN,USA e Filtek Z350 XT-3M ESPE, St. Paul, MN,USA , ambas na cor A3, inseridas no dispositivo bipartido de teflon segundo a técnica incremental adotada, técnica incremental obliqua, horizontal ou incremento único. A resina foi inserida com uma espátula metálica em incrementos horizontais ou em incrementos oblíquos, conforme a inclinação dada pelo instrumental utilizado, em incrementos de 2mm de espessura, ou ainda inserida de uma só vez, em porção única de 4mm de espessura e fotoativadas por 20 segundos, segundo indicação do fabricante. Os espécimes foram submetidos aos testes de tração para avaliar a força coesiva da resina composta e a influência da técnica incremental utilizada. Os dados obtidos foram analisados quanto à sua distribuição, à Análise de Variância (ANOVA) e ao Teste de Tukey HSD (p>0,05 %). Pode - se concluir que a técnica incremental utilizando incrementos oblíquos influencia negativamente na resistência coesiva. A Resina Filtek Z350XT possui maior resistência coesiva quando comparada à resina Filtek P90. A utilização de adesivo influencia negativamente na resistência coesiva. / The aim of this study was to evaluate the influence of incremental technique on the cohesive strength of different dental resin composites. A total of 120 conical specimens of different resin composites, Filtek P90 and Filtek Z350 XT, both in color A3, were made in a bipartite teflon device with the following dimensions: 4 mm base diameter of 2mm and 8mm in height. The specimens were assigned into 12 groups (n = 10), 6 groups without the use of adhesive and 6 groups with the use of adhesive. The cavity was filled with a metal spatula in oblique or horizontal increments of 2mm thick or inserted at once in one portion 4mm thick and each increment was light-cured for 20 seconds following manufactures instructions. The specimens were subjected to microtensile tests to evaluate the cohesive strength of the resin composite and the influence of incremental technique used. Data were submitted to ANOVA and Tukey\'s HSD test (p<0,05%).Can be concluded that the incremental technique using increments oblique negatively influence the cohesive strength. The resin Filtek Z350XT has greater cohesive resistance when compared to Filtek P90. The use of adhesive negatively influence the cohesive resistance

Actualmente los materiales cementicios suplementarios como el metacaolín, son comúnmente empleados en la industria cementera y de la construcción, debido a factores ambientales, económicos y técnicos. La mayoría de estudios que evalúan la influencia del metacaolín en sistemas cementicios, se enfocan en aspectos de desempeño y de resistencia mecánica, en edades avanzadas. Existen pocos estudios que evalúan la etapa inicial de hidratación. Por tanto, este trabajo tiene como propósito entender mejor la influencia que tiene la sustitución parcial de metacaolín en pastas de cemento Portland, durante las primeras 72 horas de hidratación. Normalmente para evaluar la cinética de hidratación se analiza el calor liberado, usando un calorímetro de conducción isotérmico. Sin embargo, otra técnica relativamente nueva usada en este estudio, es medir la retracción química en forma continua; en Brasil son raros los estudios que usen retracción química para obtener la cinética de hidratación. Para tal fin se elaboraron pastas utilizando reemplazos de metacaolín de 5, 10 y 20% en masa, además de una pasta de referencia, usando una relación constante agua/sólido de 0.5. La retracción química fue medida en forma continua automatizando el método de la dilatometría, también se evaluó la cinética de hidratación usando un calorímetro isotérmico. Adicionalmente, el desarrollo de los productos hidratados fue estudiado por análisis termogravimétrico y difracción de rayos X. Los resultados obtenidos muestran que existe una excelente relación entre la retracción química y la calorimetría y que la adición de metacaolín produce cambios en la cinética de hidratación, que también afectan a la retracción química. / Currently the supplementary cementitious materials such as metakaolin are commonly used in the cement and construction industry, due to environmental, economic and technical factors. Most studies evaluating the influence of metakaolin in cementitious systems focus on aspects of performance and mechanical strength at older ages. There are few studies evaluating the initial stage of hydration. Therefore, this paper aims to better understand the influence of the partial replacement of metakaolin in Portland cement pastes during the first 72 hours of hydration. Normally to evaluate the kinetics of hydration heat released is analyzed using an isothermal calorimeter. Nevertheless, another relatively new technique used in this study is to measure the chemical shrinkage continuously; in Brazil are rare studies using chemical shrinkage to obtain hydration kinetics. This study shows the influence of partial replacement of Portland cement by metakaolin in the hydration reactions and chemical shrinkage of cementitious pastes. For this, pastes were prepared using metakaolin replacements of 5, 10 and 20% by mass, and a reference paste, using a constant water/solid ratio of 0.5. Chemical shrinkage was measured continuously automating the method of dilatometry, hydration kinetics was evaluated using an isothermal conduction calorimetry. Additionally, the development of hydrated products was studied by thermogravimetric analysis and X-ray diffraction. The results show that there is an excellent relationship between chemical shrinkage and calorimetry and the addition of metakaolin leads to changes of the hydration kinetics, which also affect the chemical shrinkage.

Esta pesquisa consiste no estudo da deformabilidade de estruturas de concreto, decorrente da retração e fluência. Este estudo envolve aspectos de caracterização do concreto por meio de ensaios em laboratório de retração, de fluência e de suas propriedades mecânicas (resistência à compressão, resistência à tração por compressão diametral e módulo de elasticidade). Por meio dessa caracterização, foram obtidos parâmetros experimentais de fluência e retração baseados em traços de concreto utilizados em obras que possam ser confrontados àqueles indicados pelas normas vigentes. Além disso, nove protótipos de pilares com duas taxas de armadura foram mantidos sob carga constante em um ambiente controlado de temperatura e umidade relativa durante 91 dias. O principal objetivo deste ensaio foi o estudo da influência da taxa de armadura na redistribuição de esforços do concreto para armadura devido às propriedades de fluência e retração em protótipos de pilares. Para prever esta redistribuição de esforços, foram feitas simulações numéricas utilizando o Método dos Elementos Finitos. As simulações consideraram tanto os modelos de previsão de fluência e retração disponível no programa quanto os resultados provenientes da caracterização laboratorial. Além disso, foram avaliadas outras formulações teóricas que prevêem as deformações ao longo do tempo em pilares. Um dos modelos de fluência que melhor se ajustou ao traço dos pilares foi calibrado e os resultados alimentaram as formulações teóricas. Os resultados teóricos foram confrontados com os observados na monitoração dos protótipos. Neste contexto, a caracterização das propriedades de fluência e retração do concreto e os indicadores estatísticos que apontam os melhores modelos de previsão representam uma contribuição ao conhecimento do comportamento de materiais usados atualmente, de forma a tornar possível o uso de um modelo eficaz em projetos de estruturas em concreto armado para os concretos estudados. Além disso, o estudo da fluência e retração em protótipos de pilares forneceu um melhor entendimento da redistribuição de tensões do concreto para armadura. Finalmente, o ajuste do modelo de fluência demonstrou ser eficaz para previsão das deformações obtidas experimentalmente. / This thesis presents the study of the time dependent deformation of concrete structures due to creep and shrinkage. Creep, shrinkage, compressive strength, splitting tensile strength and modulus of elasticity tests were performed in mixtures commonly used in construction. Experimental parameters were obtained from these mechanical characterizations and creep and shrinkage models were evaluated. Nine short reinforced and non reinforced columns were long term loaded and monitored for 91 days. The tests were performed in a temperature and relative humidity controlled ambient. The redistribution of internal stresses from concrete to reinforcement due to creep and shrinkage were investigated. In order to analyze the redistribution of internal stresses Finite Element Method simulations were performed. Creep and shrinkage models and experimental data were considered in simulations. Other formulations were also applied to examine the experimental data from columns. One of the creep models which best fit the experimental data of the column mixture characterization was adjusted and the model results were used in these formulations. Numerical results and experimental data were evaluated. In this context, the characterization of creep and shrinkage of concrete and statistical evaluation of models contribute to know the behaviour of present-day construction materials and makes possible the use of efficiency models. Besides the study of creep and shrinkage in columns enhance the knowledge of internal stresses redistribution. Finally, an updating creep model was successfully applied to concrete experimental data.

O objetivo deste estudo foi verificar a influência das dimensões do corpo-de-prova sobre a tensão de contração de um compósito em sistemas de teste com compliances conhecidos e em um sistema hipotético com compliance zero. A distribuição das tensões foi avaliada através de análise por elementos finitos. Cilindros de vidro com 2, 4 ou 6 mm de diâmetro foram fixados nas garras da máquina de ensaios (Instron 5565). As alturas dos corpos-de-prova foram definidas ajustando-se a distância entre os cilindros (0,5, 1, 2 e 4 mm). Um compósito quimicamente ativado (Bisfil 2B, Bisco) foi aplicado entre os cilindros. A força máxima após 30 min foi dividida pela área da seção transversal do corpo-de-prova para se obter a tensão nominal (MPa). A partir dos valores do módulo de elasticidade do vidro, diâmetro do cilindro e força desenvolvida, o valor da tensão nominal experimental foi corrigida para estimar a tensão que teria sido obtida caso o sistema tivesse compliance igual a zero. Estes valores foram utilizados na análise por elementos finitos. Alturas menores geraram maior tensão nominal apenas nos diâmetros 4 mm e 6 mm. Houve uma correlação linear direta entre tensão e fator-C. Porém, o efeito de borda ficou evidente nas curvas dos dados agrupados por diâmetro. Não houve relação entre tensão nominal e volume de compósito para todo o conjunto de dados. A correção da tensão resultou em valores mais altos e ampliou as diferenças de tensão entre as alturas. A simulação por elementos finitos evidenciou pronunciado efeito de borda em situações de alto confinamento e os valores da tensão máxima de Von Mises foram mais altos do que a tensão nominal 9 corrigida em qualquer condição experimental. Foi possível concluir que as dimensões do espécime influenciaram os valores de tensão nominal. É possível inferir que a eliminação do compliance tornaria esta influência mais evidente. Existe um pronunciado efeito de borda neste tipo de ensaio, principalmente em condições de alto confinamento. / The objective of the present study was verify the influence of specimen dimensions on polymerization shrinkage stress of a dental composite in testing systems of known compliance and in a hypothetical system with zero compliance. Stress distribution was evaluated using finite element analysis. Glass rods with 2, 4, or 6 mm diameters were attached to a universal testing machine (Instron 5565). Specimen height was defined by adjusting the distance between the rods (0.5, 1, 2 or 4 mm). A self-cure composite (Bisfil 2B, Bisco) was applied between them. Maximum contraction force after 30 min was divided by the cross-sectional area of the specimen in order to obtain nominal stress (MPa). The corrected nominal stress was calculated using the elastic modulus and elongation of the components of the system, together with the force registered during testing. Corrected values were used in the finite element analysis. Shorter specimens generated higher nominal stress only for the 4 mm and 6 mm specimens. There was a direct linear correlation between stress and C-factor. However, the effect of boundary restraints became evident when data were grouped by diameter. No correlation was found between nominal stress and specimen volume. Data correction for compliance amplified the differences in stress produced by different heights. Finite elements analysis revealed an accentuated boundary effect in high confinement groups. Maximum Von Mises stress was higher than corrected nominal stress in all groups. It was concluded that specimen dimensions influenced test results. Eliminating the influence of system compliance made the effect of specimen 11 dimensions on stress more evident. Boundary restraints have a strong influence in test results, mostly in highly confined conditions.

Barreiras impermeáveis são uma necessidade em várias obras de engenharia e, em geral, naquelas destinadas à disposição de resíduos, como os aterros e as lagoas de efluentes. Solos compactados têm sido largamente utilizados para essa finalidade. Nesse sentido, esses solos devem ter características apropriadas, como baixa permeabilidade, as quais devem permanecer frente às solicitações de obra. Este trabalho trata do estudo da potencialidade do uso de solos lateríticos compactados em barreiras impermeáveis para sistemas de contenção de resíduos. Neste estudo avaliaram-se os efeitos da umidade e da energia de compactação em duas propriedades importantes para a finalidade desejada, a permeabilidade e a contração, por meio de corpos de prova de dimensões reduzidas, tal qual utilizado na metodologia MCT. Verificou-se que, em geral, a condutividade hidráulica diminuiu com o aumento da umidade, até a umidade ótima, permanecendo praticamente constante ou diminuindo ligeiramente a partir daí. O aumento da energia de compactação diminuiu as condutividades hidráulicas de forma pronunciada no ramo seco da curva de compactação, mas após a umidade ótima as variações foram pequenas para energias acima de 12 golpes. As mínimas condutividades hidráulicas obtidas foram da ordem de '10 POT.-7' cm/s para vários solos ensaiados. Outro fator que também influenciou na diminuição da condutividade hidráulica dos solos foi o aumento da porcentagem de argila. No que se refere às contrações dos solos, o aumento da umidade acarretou em aumento das contrações axiais, que atingiram valores máximos da ordem de 4%. Os solos mais arenosos apresentaram as menores contrações axiais, não ultrapassando valores da ordem de 1%, enquanto para os solos argilosos as contrações médias foram da ordem de 2%. O aumento da energia de compactação acarretou ligeiro aumento das contrações axiais / Impermeable barriers are a need in several engineering works, specially in waste containment systems and effluents ponds. Compacted soils have been used for that purpose. In that sense, the candidate soils should have appropriate characteristics, such as low permeability, which must remain throughout the design life. This work deals with the potentiality of using lateritic compacted soils in impermeable barriers for waste containment systems. In this study the influence of the water content and the compacting energy on the permeability and on the shrinkage of those soils was studied, through specimens of reduced dimensions, as used in the MCT methodology. It was verified that, in general, the hydraulic conductivity decreased with the increase of the water content, until the optimum water content, staying practically constant since then. The increase of the compacting energy reduced the hydraulic conductivities in the dry side of the compacting curve, but beyond the optimum water content the variations were small for energies larger than 12 blows. The lower hydraulic conductivities obtained were of the order of '10 POT.-7' cm/s for several soils. Hydraulic conductivity was also reduced with the increase of the clay percentage. Regarding soil shrinkage the increase of the water content caused an increase on the axial shrinkage that reached maximum values in the order of 4%. The sandy soils presented the smallest axial shrinkage (lower than 1%), while for the clayey soils the average shrinkage reached about 2%. The increase of the compacting effort caused a little increase of the axial shrinkage

Os biopolímeros comestíveis, tais como amido e alginato, podem ser utilizados na formulação de géis com elevada capacidade de retenção de água. A secagem convectiva pode ser utilizada para a remoção da umidade em géis. Os parâmetros da secagem (temperatura, velocidade do ar e umidade de equilíbrio) necessitam ser monitorados para a produção de um sólido seco e sem degradação de compostos ativos. A modelagem matemática da secagem pelo método numérico de elementos finitos em COMSOL Multiphysics tem sido utilizada para simular a secagem, usando um número reduzido de ensaios experimentais. Este trabalho teve como objetivo o desenvolvimento de modelos analíticos e numéricos para predizer a umidade e tamanho de fatias de géis de amido de milho e alginato de cálcio durante a secagem convectiva. O acoplamento entre a transferência de massa e encolhimento das fatias durante a secagem foi simulado e a difusividade mássica efetiva foi obtida pelo ajuste não linear aos dados experimentais. Três modelos foram utilizados como estudos de caso: A secagem de géis contendo 60% de água e 5.4% de amido gelatinizados (GC90), foram descritas pela solução analítica da segunda lei de Fick (R2 = 0.997-0.998); A secagem de géis contendo 60% de água e 5.4% de amido nativo (RC90), foram mais bem explicadas pelo modelo analítico com inclusão do termo de encolhimento (R2 = 0.992); O modelo numérico desenvolvido em COMSOL Multiphysics descreveu adequadamente a secagem de géis formulados com 86% de água e 34% amido gelatinizado e não-gelatinizado (GC50 e RC90), dando um R2 de 0.983-0.992. O encolhimento foi estimado a partir do fluxo molar de água, enquanto a deformação da geometria foi simulada pelo método arbitrário Lagrangian-Eulerian (ALE). A inclusão do termo de encolhimento modificou o perfil de taxa de secagem e o período de pseudo-taxa constante foi observado. O modelo desenvolvido neste trabalho pode ser aplicado em estudos de secagem de géis, alimentos e outros materiais que apresentam elevada razão de encolhimento. / Biopolymers, such as starch and alginate, can be used in the formulation of gels with high water retention. The convective drying can be applied to gel moisture removing. Drying parameters (temperature, air velocity and equilibrium moisture) should be monitored in view of producing a dry solid without degradation of active compounds. The mathematical modeling by the finite element method in COMSOL Multiphysics has been used to simulate drying profiles, with reduced experimental runs. This work aimed at developing of analytical and numerical models to predict the moisture and size of slices of gels containing cornstarch and calcium alginate, during convective drying. The coupling between mass transfer and shrinkage of slices during drying was simulated and the effective mass diffusivity was obtained by non-linear adjustment to the experimental data. Three models have been used as case studies obtained the effective mass diffusivity. Drying of gels containing 60% water and 5.4% gelatinized cornstarch (GC90 samples) as well fitted by the analytical solution of Fick\'s second law (R2 = 0.997-0.998). Drying of gels containing 60% water and 5.4% native starch (RC90 samples) as explained by Fick\'s analytical model while inclusion of the shrinkage term (R2 = 0.992). The numerical model developed in COMSOL Multiphysics adequately described the drying of gels formulated with 86% water and 34% of starch, gelatinized or non-gelatinized, (GC50 and RC90 samples), giving a R2 of 0.983-0.992. The shrinkage was estimated by the molar flux of water, while the geometry shrinkage was simulated by the Arbitrary Lagrangian-Eulerian (ALE) method. The inclusion of the shrinkage modified the drying rate profiles and a pseudo-constant rate period was observed. The model developed in this work can be applied to drying studies of gels, food and other materials that have a high shrinkage ratio.

This thesis is concerned with a fundamental unit of the economy: Households. Even in advanced economies, upwards of 70% of the population live in households composed of multiple people. A large number of decisions are taken at the level of the household, that is to say, they are taken jointly by household members: How to raise children, how much and when to work, how many cartons of milk to purchase. How these decisions are made is therefore of great importance for the people who live in them and for their well-being.But precisely because household members make decisions jointly it is hard to know how they come about and to what extent they benefit individual members. This is why households are often viewed as unique decision makers in economics. Even if they contain multiple people, they are treated as though they were a single person with a single set of preferences. This unitary approach is often sufficient and can be a helpful simplification. But in many situations it does not deliver an adequate description of household behavior. For instance, the unitary model does not permit the study of individual wellbeing and inequality inside the household. In addition, implications of the unitary model have been rejected repeatedly in the demand literature.Bargaining models offer an alternative where household members have individual preferences and come to joint decisions in various ways. There are by now a great number of such models, all of which allow for the study of bargaining power, a measure of the influence a member has in decision making. This concept is important because it has implications for the welfare of individuals. If one household member’s bargaining power increases, the household’s choices will be more closely aligned with that member’s preferences, ceteris paribus.The three chapters below can be divided into two parts. The first part consists of Chapter 1, which looks to detect the influence of intra-household bargaining in a specific set of consumption choices: Consumption of the arts. The research in this chapter is designed to measure aspects of the effect of bargaining power in this domain, but does not seek to quantify bargaining power itself or to infer economic well-being of household members.Precisely this last point, however, is the focus of the second part of the thesis, consisting of Chapters 2 and 3. These focus specifically on the recovery of one measure of bargaining power, the resource share. Resource shares have the advantage of being interpretable in terms of economic well-being, which is not true of all such measures. They are estimated as part of structural models of household demand. These models are versions of the collective model of household decision making.Pioneered by Chiappori (1988) and Apps and Rees (1988), the collective model has become the go-to alternative to unitary approaches, where the household is seen as a single decision-making unit with a single well-behaved utility function. Instead, the collective model allows for individual utility functions for each member of the household. The model owes much of its success to the simplicity of its most fundamental assumption: That whatever the structure of the intra-household bargaining process, outcomes are Pareto-efficient. This means that no member can be made better off, without making another worse off. Though the model nests unitary models as special cases, it does have testable implications.The first chapter of the thesis is entitled “Household Decisions on Arts Consumption” and is joint work with Caterina Mauri, who has also collaborated with me on many other projects in her capacity as my girlfriend. In it, we explore the role of intra-household bargaining in arts consumption. We do this by estimating demand for various arts and cultural events such as the opera or dance performances using a large number of explanatory variables. One of these variables plays a special role. This variable is a distribution factor, meaning that it can be reasonably assumed to affect consumption only through the bargaining process, and not by modifying preferences. Such variables play an important role in the household bargaining literature. Here, three such variables are used. Among them is the share of household income that is contributed by the husband, the canonical distribution factor.The chapter fits into a literature on drivers of arts consumption, which has shown that in addition to such factors as age, income and education, spousal preferences and characteristics are important in determining how much and which cultural goods are consumed. Gender differences in preferences in arts consumption have also been shown to be important and to persist after accounting for class, education and other socio-economic factors (Bihagen and Katz-Gerro, 2000).We explore to what extent this difference in preferences can be used to shed light on the decision process in couples’ households. Using three different distribution factors, we infer whether changes in the relative bargaining power of spouses induce changes in arts consumption.Using a large sample from the US Current Population Survey which includes data on the frequency of visits to various categories of cultural activities, we regress atten- dance rates on a range of socio-economic variables using a suitable count data model.We find that attendance by men at events such as the opera, ballet and other dance performances, which are more frequently attended by women than by men, show a significant influence of the distribution factors. This significant effect persists irrespec- tively of which distribution factor is used. We conclude that more influential men tend to participate in these activities less frequently than less influential men, conditionally on a host of controls notably including hours worked.The second chapter centers around the recovery of resource shares. This chapter is joint work with Denni Tommasi, a fellow PhD student at ECARES. It relies on the collective model of the household, which assumes simply that household decisions are Pareto-efficient. From this assumption, a relatively simple household problem can be formulated. Households can be seen as maximizers of weighted sums of their members’ utility functions. Importantly the weights, known as bargaining weights (or bargaining power), may depend on many factors, including prices. The household problem in turn implies structure for household demand, which is observed in survey data.Collective demand systems do not necessarily identify measures of bargaining power however. In fact, the ability to recover such a measure, and especially one that is useful for welfare analysis, was an important milestone in the literature. It was reached by (Browning et al. 2013) (henceforth BCL), with a collective model capable of identi- fying resource shares (also known as a sharing rule). These shares provide a measure of how resources are allocated in the household and so can be used to study intra- household consumption inequality. They also take into account that households gen- erate economies of scale for their members, a phenomenon known as a consumption technology: By sharing goods such as housing, members of households can generate savings that can be used elsewhere.Estimation of these resource shares involves expressing household budget shares functions of preferences, a consumption technology and a sharing rule, each of which is a function of observables, and letting the resulting system loose on the data. But obtaining such a demand system is not free. In addition to the usual empirical speci- fications of the various parts of the system, an identifying assumption has to be made to assure that resource shares can be recovered in estimation. In BCL, this is the assumption that singles and adult members of households share the same preferences. In Chapter 2, however, an alternative assumption is used.In a recent paper, Dunbar et al. (2013) (hereafter DLP) develop a collective model based on BCL that allows to identify resource shares using assumptions on the simi- larity of preferences within and between households. The model uses demand only for assignable goods, a favorite of household economists. These are goods such as mens’ clothing and womens’ clothing for which it is known who in a household consumes them. In this chapter, we show why, especially when the data exhibit relatively flat Engel curves, the model is weakly identified and induces high variability and an im- plausible pattern in least squares estimates.We propose an estimation strategy nested in their framework that greatly reduces this practical impediment to recovery of individual resource shares. To achieve this, we follow an empirical Bayes method that incorporates additional (or out-of-sample) information on singles and relies on mild assumptions on preferences. We show the practical usefulness of this strategy through a series of Monte Carlo simulations and by applying it to Mexican data.The results show that our approach is robust, gives a plausible picture of the house- hold decision process, and is particularly beneficial for the practitioner who wishes to apply the DLP framework. Our welfare analysis of the PROGRESA program in Mexico is the first to include separate poverty rates for men and women in a CCT program.The third Chapter addresses a problem similar to the one discussed in Chapter 2. The goal, again, is to estimate resource shares and to remedy issues of imprecision and instability in the demand systems that can deliver them. Here, the collective model used is based on Lewbel and Pendakur (2008), and uses data on the entire basket of goods that households consume. The identifying assumption is similar to that used by BCL, although I allow for some differences in preferences between singles and married individuals.I set out to improve the precision and stability of the resulting estimates, and so to make the model more useful for welfare analysis. In order to do so, this chapter approaches, for the first time, the estimation of a collective household demand system from a Bayesian perspective. Using prior information on equivalence scales, as well as restrictions implied by theory, tight credible intervals are found for resource shares, a measure of the distribution of economic well-being in a household. A modern MCMC sampling method provides a complete picture of the high-dimensional parameter vec- tor’s posterior distribution and allows for reliable inference.The share of household earnings generated by a household member is estimated to have a positive effect on her share of household resources in a sample of couples from the US Consumer Expenditure survey. An increase in the earnings share of one percentage point is estimated to result in a shift of between 0.05% and 0.14% of household resources in the same direction, meaning that spouses partially insure one another against such shifts. The estimates imply an expected shift of 0.71% of household resources from the average man to the average woman in the same sample between 2008 and 2012, when men lost jobs at a greater rate than women.Both Chapters 2 and 3 explore unconventional ways to achieve gains in estimator precision and reliability at relatively little cost. This represents a valuable contribution to a literature that, for all its merits in complexity and ingenious modeling, has not yet seriously endeavored to make itself empirically useful. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished