Esta tese de doutorado consiste em três ensaios aplicados de macroeconomia. O primeiro ensaio retoma o clássico resultado do artigo de Meese e Rogoff (1983), em que os autores encontram fortes evidências de que nenhum modelo estrutural para a taxa de câmbio supera as projeções de um modelo random walk. Neste primeiro ensaio, comparamos o erro das projeções para a taxa de câmbio, efetuadas por bancos, instituições financeiras e consultorias econômicas, captadas no ranking Top-5 do Banco Central do Brasil, com as projeções de um modelo random walk e um modelo estrutural, o de paridade não coberta de taxa de juros, para três horizontes de previsão. Os resultados mostram que o modelo random walk tem maior índice de acerto em comparação com os métodos utilizados pelas instituições participantes da pesquisa e em comparação ao método estrutural. Este índice de acerto aumenta com o prazo de projeção. O segundo ensaio trata dos determinantes das expectativas de inflação no Brasil. As expectativas de inflação são uma das mais importantes variáveis na determinação da inflação futura, determinando a condução da política monetária. Através de modelagem econométrica, encontramos que as variáveis que afetam as expectativas de inflação são: a) meta de inflação é a variável mais importante, funcionado como âncora das expectativas; b) inflação passada; c) hiato do produto; d) taxa de câmbio; e) preços internacionais; e f) taxa de juros. Variáveis de política fiscal não parecem ser importantes na determinação das expectativas de inflação. O terceiro ensaio volta a tratar da taxa de câmbio, tratando de entender o impacto das desvalorizações do Real sobre o comportamento das empresas. Sabese que os impactos na atividade econômica de uma desvalorização cambial podem ser positivos ou negativos. Para as firmas, o benefício se dá em termos de competitividade, dada a redução nos custos. Mas, se as firmas tiverem dívida atrelada à moeda estrangeira, a desvalorização pode ter mais custos do que benefícios, dado as restrições à atuação das empresas via mercado de crédito. Este é o efeito de balanço patrimonial. Este terceiro ensaio trata de contribuir na identificação dos impactos destas desvalorizações sobre o comportamento dos investimentos de empresas brasileiras. Através de dados microeconômicos, os resultados das estimações não permitem concluir qual dos dois efeitos, de balanço patrimonial ou de competitividade, é mais importante. Entretanto, a separação da amostra em firmas de diferentes tamanhos evidencia um efeito de balanço patrimonial superior ao efeito de competitividade no caso de firmas grandes. / This doctoral thesis consists of three essays in applied macroeconomics. The first essay retakes the classic result of the article by Meese and Rogoff (1983), in which the authors found strong evidence that no structural model for the exchange rate surpasses the projections of a random walk model. In this first essay we compare the error of the projections for the exchange rate, effected by banks, financial institutions and economic consultants, caught in ranking Top-5 of the Brazilian Central Bank, with the projections of a random walk model and a structural model of uncovered interest parity for three horizons of forecast. The results show that the random walk model has greater index of rightness in comparison with the methods used for the participant institutions of the research and in comparison with the structural method. This index of rightness increases with the projection stated period. The second essay deals with the determinants of inflation expectations in Brazil. Expectations of inflation are one of the most important variables in determining the future inflation, determining the conduct of monetary policy. Through econometric modeling we find that the variables that affect inflation expectations are: a) inflation target it is the most important variable, worked as anchor of expectations; b) past inflation; c) the product gap; d) exchange rate; e) international prices; and f) interest rate. Variables of fiscal policy do not seem to be important in the determination of inflation expectations. The third essay is once again dealing with the exchange rate, trying to understand the impact of the devaluation of the Real on corporate behavior. It is known that the impacts on economic activity of currency devaluation can be positive or negative. For firms, the benefit is given in terms of competitiveness, given the reduction in costs. But, if the firms have geared to the foreign currency debt, the devaluation may have more costs than benefits, given the restrictions on the performance of companies by market credit. This is the effect of balance sheet. This work comes to help in identifying the impact of these devaluations on the performance of the investments of Brazilian companies. Through microeconomic data, the results of the estimates can not conclude which of the two effects, balance sheet or competitiveness, is more important. Meanwhile, the separation of the sample in firms of different sizes shows an effect of balance sheet higher than the effect of competitiveness in the case of large firms.

Os modelos expostos nesta Tese possuem em comum a discussão macroeconômica sobre a composição ótima da dívida pública brasileira. Logo, esta Tese busca preencher lacunas presentes na literatura sobre a escolha ótima da composição do endividamento público, tendo em vista o modelo de suavização da tributação, exposto inicialmente em Goldfajn (2000). Logo, os modelos aqui utilizados estudam a composição ótima da dívida pública, tendo como ponto de partida o modelo clássico de suavização da tributação, exposto em Goldfajn (2000), no qual pressupõe-se a existência de três tipos de endividamento (nominal, ou prefixado; cambial; e pós-fixado), e repactuação constante da dívida pública indexada (de modo que a composição do endividamento público pode ser completamente alterada a cada período). A discussão se distingue da abordagem tradicional por utilizar informação condicional, ao invés da abordagem não condicional, incrementando precisão e qualidade aos resultados em termos de erro quadrático médio. Naturalmente, temos no GARCH multivariado um método de estimação mais adequado. Outra dimensão aqui discutida é a expansão do modelo tradicional com o estudo de outras abordagens, que consideram a decomposição da dívida pós-fixada em duas proporções distintas de acordo com o instrumento de indexação utilizado (a saber, dívida flutuante, quando os títulos são indexados a taxas de juros, e dívida pós-fixada em preços, quando o instrumento de indexação utilizado é representado por um índice de preços), além de considerar a possibilidade de resolução do problema em horizonte infinito (no qual a autoridade fiscal pode considerar a existência de diferentes maturidades para os títulos públicos, sem repactuação completa da composição a cada período). A abordagem com três dívidas e horizonte infinito já havia sido proposta por Cysne (2007), muito embora tenha sido estimada de forma não condicional. Os resultados obtidos mostram que as proporções teóricas ótimas apresentam dinâmicas muito próximas àquelas observadas na gestão da dívida pública, com maior precisão nos modelos solucionados em dois períodos. Além disso, os resultados também comprovam os trade-offs tradicionalmente observados na gestão do endividamento público, além de propor e confirmar novos trade-offs, compatíveis com as expansões teóricas realizadas. / The models shown in this thesis have in common the macroeconomic discussion on the optimal composition of the public debt. Therefore, this thesis seeks to fill gaps in the literature about the optimal choice of the composition of public debt, in view of the tax smoothing model, exposed initially in Goldfajn (2000). Thus, the models used here to study the optimal composition of the public debt, taking as its starting point the classic model of tax smoothing, exposed in Goldfajn (2000), which assumes the existence of three types of debt (nominal; exchange-rate-denominated, and indexed), and constant renegotiation of the public debt indexed (so that the composition of public debt can be completely changed every period). The discussion distinguishes itself from the traditional approach by using conditional information, rather than the non-conditional approach, increasing accuracy and quality of the results in terms of mean square error. Of course, we have one in multivariate GARCH estimation method more suitable. Another dimension discussed here is the expansion of the traditional model to the study of other approaches that consider the decomposition of indexed debt in two different proportions according to the instrument used for indexing (ie, interest rate indexing when the bonds are indexed in interest rates and indexing price debt when the instrument used index is represented by a price index), and consider the possibility of solving the problem in infinite period (where the government may consider the existence of different maturities for the bonds, without complete renegotiation the composition in each period). The approach with three debts and infinite horizon had already been proposed by Cysne (2007), although it has been estimated and not conditional. The results show that the proportions have great theoretical dynamics very close to those observed in the management of public debt, more accurately models solved in two periods. Moreover, the results also show the trade-offs traditionally observed in the management of public debt, and to propose and confirm new trade-offs, consistent with the theoretical expansions performed.

Warm inflation is an implementation of exponential early-universe expansion that incorporates interactions between the inflaton field and its environment. These interactions allow the inflaton to dissipate some of its energy into other fields, which may then thermalise and form a radiation bath. A radiation bath present throughout inflation changes the inflaton dynamics and introduces thermal fluctuations that enhance the spectrum of primordial density perturbations. In the models we consider, the inflaton decays into the light particles of the radiation bath via heavy mediator particles. Warm inflation is subject to a complicated set of constraints which typically requires a large number of such mediator fields to be included in the model. The motivation for this work was to use the parametric dependence of the full low-temperature dissipation coefficient to uncover regimes where this number can be reduced. Previous studies have examined primarily the low-momentum regime of the dissipation coefficient, where inflaton dissipation occurs via off-shell mediator particles. In the low-temperature regime, the production of on-shell mediators in the so-called pole regime suffers from Boltzmann suppression and was therefore thought to be negligible. It has been found, however, that the exponential suppression can be compensated by a sufficiently small effective coupling between the mediator fields and the light fields. In this thesis, we present a numerical code that scans the parameter space of warm-inflation models including both the low-momentum and the pole contribution to the dissipation coefficient. We generate random values for the parameters of the model and the initial conditions of the field and the radiation density; we then solve the full equations of motion for the radiation density and the inflaton field using the general low-temperature dissipation coefficient. Our search includes chaotic, hybrid, and hilltop models, each of which inhabits different regions of warm-inflation parameter space. Our main finding is that the pole contribution to inflaton dissipation significantly extends the parameter ranges accessible to warm inflation. Specifically, we can achieve 50 e-folds of inflation and a spectral index compatible with Planck data with fewer mediator fields and smaller coupling constants. For instance, while low-momentum-dominated dissipation typically requires O(10⁶) mediator fields, we find pole-dominated solutions with as few as O(10⁴) for the quadratic hilltop potential. It is clear that the inclusion of the pole contribution opens up interesting model-building possibilities and that the parametric dependence of the full dissipation coefficient holds promise for achieving even greater reductions of the field content.

This study examines the relationship between in ation and price dispersion during the hyperin ationary episode in Brazil. We look at micro data on price dynamics through the perspective of dispersion at the store level, building on the informational consequences of high price dispersion. Rather than focus on which theoretical framework best explains the relative price variability seen on the data, we focus on a top-down approach to the information embedded in prices: we analyze price setting behavior from the perspective of economic segments as whole and from the perspective of each seller taken individually. In the former case we seek to answer the following: do higher levels of in ation favor higher price dispersion? In the latter, we focus on the time-series properties of each of more than 150 real price trajectories in both high and low in ation periods. We provide further empirical evidence of the loss of information embedded in prices, be it deriving from greater overall dispersion or from a greater volatility in each seller\'s price trajectory relative to its peers\'. Our findings extend previous results, accounting for a higher level of in ation, a longer time span and a broader selection of items. / Este trabalho investiga a relação entre inflação e dispersão de preços durante a experiência de hiperinflação vivida no Brasil. Estudamos micro dados de preços sob a perspectiva da dispersão no nível do vendedor, buscando evidências das consequências informacionais de uma alta dispersão de preços. Ao invés de investigar qual arcabouço teórico melhor explica a variabilidade de preços relativos encontrada nos dados, focamos em uma abordagem sobre a informação incorporada nos preços que vai do geral para o particular: analisamos primeiramente a formação de preços de maneira agregada e depois sob o ponto de vista do vendedor individualmente. No primeiro caso queremos responder à seguinte pergunta: níveis maiores de inflação geram níveis maiores de dispersão de preços? No segundo caso, focamos nas características das séries temporais de mais de 150 trajetórias de preços reais tanto para o período de alta inflação quanto para o período pós-estabilização. Fornecemos evidências empíricas adicionais da diminuição do caráter informacional dos preços, resultante tanto de uma maior dispersão das distribuições de preços, quanto da maior volatilidade na trajetória individual dos preços, relativamente aos preços dos concorrentes. Nossos resultados estendem trabalhos anteriores uma vez que considera um ambiente de inflação mais alta e mais volátil, um horizonte de tempo maior e uma seleção mais ampla de produtos.

O primeiro artigo analisa quantitativamente a importância relativa dos fatores que determinam o desempenho econômico dos países. Em especial, é incorporada à análise a possibilidade do capital ser heterogêneo. Estimativas da qualidade do capital são feitas para cada país, resultantes de um modelo teórico, e a importância de cada um dos componentes é analisada. Mesmo depois do ajuste, a qualidade do capital físico não explica grande parte da experiência de crescimento dos países. Além disso, é feita uma análise para o caso brasileiro com o arcabouço desenvolvido durante o período que vai de 1970 até 2003. Conclui-se nesta análise que a heterogeneidade do capital não explica grande parte da experiência de crescimento do Brasil. O segundo artigo apresenta um modelo que relaciona crescimento econômico, educação, investimento e regimes políticos. Para isto, propõe-se um modelo de gerações sobrepostas em que existem dois grupos de agentes: os capitalistas e os trabalhadores. Além disso, uma democracia é definida como um governo em que todos votam e, pelo fato do eleitor mediano ser também um trabalhador, os trabalhadores podem então taxar o investimento e redistribuir na forma de capital humano. O principal resultado é que a democracia desestimula o investimento de capital físico e estimula o aumento de capital humano. O terceiro artigo busca explicar o aumento do consumo após a redução da inflação causada por um controle de preços. O foco é direcionado para o consumo de bens duráveis e a dificuldade dos domicílios de se protegerem dos efeitos da inflação. Uma redução súbita na inflação reduz o preço efetivo dos bens duráveis, levando a uma expansão destes. Todos os modelos são calibrados para a experiência brasileira do Cruzado, em meados da década de 80, e dois arcabouços básicos são apresentados: um em que os domicílios não possuem acesso ao mercado de crédito e outro em que possuem acesso parcial. Além disso, é apresentada a possibilidade de reduções permanentes e temporárias da taxa de inflação. As principais conclusões do artigo são que o modelo em que os domicílios não possuem acesso a crédito e são heterogêneos nas preferências é o que mais se aproxima com os dados apresentados da experiência do plano Cruzado. / The first article analyzes quantitatively the relative importance of the factors that determine economic performance of the countries. Mainly, the empirical exercise incorporates the possibility of heterogeneous capital. Estimates of the quality of the capital are made for each country from results of a theoretical model and the importance of each one of the components is analyzed. Even after the adjustment in the quality of capital, the quality of physical capital does not explain too much of the growth experiences. Furthermore, the Brazilian experience is analyzed with the developed framework from 1970 to 2003. The main conclusion is that the heterogeneity of capital inserted in the model does not explain too much of the Brazilian growth experience. oindent The second article presents a model which relates economic growth, education, investment and political regimes. In order to do that, is presented a model of overlapping generations with two groups of agents: capitalists and workers. Furthermore, a democracy is defined as a government where everybody votes and, by the fact that the median voter is also a worker, the working class then can tax more heavily the investment and redistribute through human capital investment. The main result of the article is that democracies undermine investment in physical capital and enhances the growth of human capital. oindent The third article seeks to explain consumption booms after inflation stabilization plans centered on price controls. The focus is directed to durable goods and the difficulty for households to protect themselves from inflation. A sudden decrease in the inflation rate reduces effective consumption price of durable goods, leading to a boom. All the models are calibrated for mid-80\'s Brazil and two base simulations are presented: one in which none of the households have access to the credit market and one where households have partial access to the credit market. Other than that, it is also presented the possibility of permanent and temporary stabilization of inflation. The main conclusion of the article is that the model in which households do not have access to the credit market and are heterogeneous in preferences is the one that better explains the Brazilian experience of Cruzado.

A presente dissertação estuda empiricamente a relação entre a inflação e a distribuição de renda, utilizando dados de diversos países. A literatura empírica - baseada principalmente nos trabalhos de Deininger e Squire (1996) e Romer e Romer (1998) - tem se concentrado no estudo dos efeitos que a inflação pode ter sobre a desigualdade, e obteve diferentes conclusões sobre os mecanismos e resultados dessa influência. No entanto, alguns trabalhos teóricos recentes argumentam que há causalidade reversa nessa relação, com a desigualdade causando mudanças na inflação. Dessa forma, nossas contribuições serão: (i) tentaremos isolar os impactos da inflação sobre a distribuição de renda, usando como variáveis de controle: ciclos de crescimento, desenvolvimento econômico, questões regionais e instituições; (ii) procuraremos analisar a causalidade desta relação, utilizando como instrumento da inflação o aumento da quase-moeda. Nossos resultados indicam que há uma forte correlação entre inflação e desigualdade de renda. Porém, essa correlação não é robusta ao controle por variáveis omitidas e problemas de endogeneidade. / This dissertation estimates the relationship between inflation and income distribution, using cross-country data. The empirical literature based mainly on Deininger and Squire (1996) and Romer and Romer (1998) has focused on the impact of inflation on inequality, with mixed results. Nonetheless, recent theoretical work has suggested that causality may actually run in the opposite direction. Our contribution is twofold: (i) we try to estimate more precisely the effect of inflation on inequality by controlling for variables such as growth cycles, economic development, regional effects and institutions; (ii) we address the issue of reverse causality by using the growth rate of quasi-money as an instrument for the inflation rate. Our results indicate that there is a strong positive correlation between inflation and income inequality. Nevertheless, this correlation is not robust to controlling for omitted factors and endogeneity problems.

Consideramos uma teoria escalar acoplada não minimamente à gravitação no contexto de alguns modelos inflacionários. Mostramos como esse acoplamento inviabiliza a inflação caótica. Analisamos em seguida um modelo proposto por Linde para contornar esses problemas. Mostramos que sua realização é trivial. / We consider a scalar theory non minimally coupled to gravitation in the context of some inflationary models. We show how this coupling prevents the chaotic inflation. Then analyzed a model proposed by Linde to avoid these problems. We show that its realization is trivial.

Suen Ming-hon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 46-49). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Table of Contents --- p.iv / Introduction --- p.1 / Chapter Chapter 1 --- The Benchmark Model --- p.9 / Chapter 1.1 --- The Model --- p.9 / Chapter 1.2 --- Comparative Statics --- p.12 / Chapter 1.3 --- Local Stability --- p.13 / Chapter Chapter 2 --- Long-Run Relationships Between Money and Growth --- p.14 / Chapter 2.1 --- The Money-in-the-Utility-Function (MIUF) Model --- p.15 / Chapter 2.2 --- The Cash-in-Advance (CIA) Model --- p.19 / Chapter 2.2.1 --- The Clower-Lucas Model --- p.20 / Chapter 2.2.2 --- The Stockman Model --- p.22 / Chapter 2.3 --- The Pecuniary Transactions Costs (PTC) Model --- p.26 / Chapter Chapter 3 --- Transitional Dynamics --- p.31 / Chapter 3.1 --- The Money-in-the-Utility-Function (MIUF) Model --- p.31 / Chapter 3.2 --- The Cash-in-Advance (CIA) Model --- p.32 / Chapter 3.2.1 --- The Clower-Lucas Model --- p.32 / Chapter 3.2.2 --- The Stockman Model --- p.33 / Chapter 3.3 --- The Pecuniary Transactions Costs (PTC) Model --- p.34 / Chapter Chapter 4 --- Conclusion --- p.37 / Mathematical Appendix / Chapter A.1 --- The Benchmark Model --- p.39 / Chapter A.2 --- The Money-in-the-Utility-Function (MIUF) Model --- p.39 / Chapter A.3 --- The Cash-in-Advance (CIA) Model --- p.40 / Chapter A.3.1 --- The Clower-Lucas Model --- p.40 / Chapter A.3.2 --- The Stockman Model --- p.41 / Chapter A.4 --- The Pecuniary Transactions Costs (PTC) Model --- p.43 / Table 1 Summary of Findings --- p.45 / Reference --- p.45

Leong Chan Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 100-105). / Abstracts in English and Chinese. / Abstract --- p.i-ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Tables --- p.v / List of Figures --- p.vi / Chapter Section 1 --- Introduction --- p.1 / Chapter Section 2 --- Literature Review --- p.5 / Chapter Section 3 --- Data Description --- p.13 / Chapter 3.1 --- Transaction Prices --- p.13 / Chapter 3.2 --- Macroeconomic Variables --- p.15 / Chapter Section 4 --- Methodology --- p.19 / Chapter 4.1 --- Hedonic Pricing --- p.21 / Chapter 4.2 --- Measurements --- p.22 / Chapter 4.3 --- Stationarity --- p.24 / Chapter 4.4 --- Vector Autoregressive Model and Granger Causality --- p.27 / Chapter Section 5 --- Hypothesis Testing --- p.31 / Chapter Section 6 --- Empirical Results --- p.35 / Chapter 6.1 --- Hedonic Pricing Models --- p.35 / Chapter 6.2 --- Real Housing Price Dispersion Indicators and Macro Variables --- p.36 / Chapter 6.3 --- Stationary Tests --- p.37 / Chapter 6.4 --- Results from the Ordinary Least Square Regressions --- p.37 / Chapter 6.5 --- Results from the Vector Auto Regressive Models --- p.40 / Summary and Conclusion --- p.46 / Appendix 1 Tables --- p.49 / Appendix 2 Figures --- p.80 / Reference --- p.100

Data can be collected in the form of counts in many situations. In other words, the number of deaths from an accident, the number of days until a machine stops working or the number of annual visitors to a city may all be considered as interesting variables for study. This study is motivated by two facts; first, the vital role of the continuous Weibull distribution in survival analyses and failure time studies. Hence, the discrete Weibull (DW) is introduced analogously to the continuous Weibull distribution, (see, Nakagawa and Osaki (1975) and Kulasekera (1994)). Second, researchers usually focus on modeling count data, which take only non-negative integer values as a function of other variables. Therefore, the DW, introduced by Nakagawa and Osaki (1975), is considered to investigate the relationship between count data and a set of covariates. Particularly, this DW is generalised by allowing one of its parameters to be a function of covariates. Although the Poisson regression can be considered as the most common model for count data, it is constrained by its equi-dispersion (the assumption of equal mean and variance). Thus, the negative binomial (NB) regression has become the most widely used method for count data regression. However, even though the NB can be suitable for the over-dispersion cases, it cannot be considered as the best choice for modeling the under-dispersed data. Hence, it is required to have some models that deal with the problem of under-dispersion, such as the generalized Poisson regression model (Efron (1986) and Famoye (1993)) and COM-Poisson regression (Sellers and Shmueli (2010) and Sáez-Castillo and Conde-Sánchez (2013)). Generally, all of these models can be considered as modifications and developments of Poisson models. However, this thesis develops a model based on a simple distribution with no modification. Thus, if the data are not following the dispersion system of Poisson or NB, the true structure generating this data should be detected. Applying a model that has the ability to handle different dispersions would be of great interest. Thus, in this study, the DW regression model is introduced. Besides the exibility of the DW to model under- and over-dispersion, it is a good model for inhomogeneous and highly skewed data, such as those with excessive zero counts, which are more disperse than Poisson. Although these data can be fitted well using some developed models, namely, the zero-inated and hurdle models, the DW demonstrates a good fit and has less complexity than these modifed models. However, there could be some cases when a special model that separates the probability of zeros from that of the other positive counts must be applied. Then, to cope with the problem of too many observed zeros, two modifications of the DW regression are developed, namely, zero-inated discrete Weibull (ZIDW) and hurdle discrete Weibull (HDW) models. Furthermore, this thesis considers another type of data, where the response count variable is censored from the right, which is observed in many experiments. Applying the standard models for these types of data without considering the censoring may yield misleading results. Thus, the censored discrete Weibull (CDW) model is employed for this case. On the other hand, this thesis introduces the median discrete Weibull (MDW) regression model for investigating the effect of covariates on the count response through the median which are more appropriate for the skewed nature of count data. In other words, the likelihood of the DW model is re-parameterized to explain the effect of the predictors directly on the median. Thus, in comparison with the generalized linear models (GLMs), MDW and GLMs both investigate the relations to a set of covariates via certain location measurements; however, GLMs consider the means, which is not the best way to represent skewed data. These DW regression models are investigated through simulation studies to illustrate their performance. In addition, they are applied to some real data sets and compared with the related count models, mainly Poisson and NB models. Overall, the DW models provide a good fit to the count data as an alternative to the NB models in the over-dispersion case and are much better fitting than the Poisson models. Additionally, contrary to the NB model, the DW can be applied for the under-dispersion case.