[pt] O Capital Asset Pricing Model (CAPM) é o modelo mais difundido e utilizado para determinação do custo de capital de empresas e estimação do retorno esperado de ações. Neste modelo, o parâmetro fundamental é o beta, que define a intensidade em que determinado ativo é exposto aos retornos do mercado. O objetivo deste trabalho é avaliar a estabilidade dos betas de uma vasta quantidade de ações no mercado brasileiro em três períodos de alta volatilidade: a crise asiática de 1997, a turbulência no mercado financeiro pré-eleições 2002 e a crise financeira de 2008, nas quais foram analisadas 55, 79 e 172 empresas respectivamente. Cada ciclo de crise foi dividido em três períodos de 52 semanas e os respectivos betas foram comparados utilizando testes de Chow e com regressões com variáveis dummy. Os resultados de ambos os testes foram similares para as crises analisadas, indicando que entre 11 porcento e 27 porcento das empresas apresentaram variação de seus betas, com 5 porcento de significância, quando comparados os períodos pré-crise e durante a crise. Não obstante, ao confrontar períodos pré-crise e pós-crise, a maior parte das empresas que apresentaram variação anteriormente não rejeitaram a hipótese de estabilidade. Estes resultados indicam que, conforme esperado, os betas tendem a ser estáveis no longo prazo. / [en] The Capital Asset Pricing Model (CAPM) is the most widespread model, used to determine the cost of capital of firms and estimate expected stock returns. In this model, the most important parameter is the beta, which defines the magnitude of exposition to market returns, for a particular asset. The objective of this essay is to evaluate beta stability of a vast amount of shares in the Brazilian stock market in three highly volatile periods: the Asian crisis in 1997, the financial market turmoil before 2002 presidential elections and the 2008 financial crisis. The sample included 55, 79 and 172 companies, respectively. Each crisis cycle was then divided into three periods of 52 weeks and then the stability of their betas was measured using regressions with dummy variables and Chow tests. We have reached similar results for the crises analyzed, indicating that between 11 percent and 27 percent of the companies changed their betas when comparing pre-crisis and during crisis periods, with a 95 percent confidence level. Nevertheless, by comparing pre-crisis and post-crisis periods, most of the companies that exhibited change in their betas when entering the crisis, did not reject the stability hypothesis. These results indicate that, as expected, betas tend to be stable in the long term.

nÃo hà / Este estudo teve como objetivo investigar a existÃncia de uma quebra estrutural na relaÃÃo entre o setor bancÃrio e o IBOVESPA durante o perÃodo de 1 de janeiro de 2007 a 29 de julho de 2011, em consequÃncia da crise financeira ocorrida em 2008. Foram empregadas tÃcnicas tradicionais em FinanÃas e Econometria para analisar os impactos da referida crise sobre o setor bancÃrio brasileiro, tomando por base as cotaÃÃes diÃrias de fechamento das aÃÃes dos principais bancos brasileiros: Banco do Brasil, Bradesco, Itaà e do IBOVESPA. Na metodologia utilizou-se o modelo de apreÃamento de ativos, CAPM, na mensuraÃÃo do risco sistÃmico. Observou-se que as evidÃncias estatÃsticas, obtidas com os testes de Chow e teste t para diferenÃa de mÃdias, indicam fundamentalmente, que foi possÃvel captar um efeito diferenciado durante a crise de 2008 entre os bancos privados e o banco pÃblico em relaÃÃo ao risco sistÃmico, alÃm de captar uma mudanÃa estrutural em 24 de outubro de 2008, mudanÃa essa detectada a partir do teste de Chow. / This research aimed to investigate the existence of a structural break in the relationship between the banking sector and IBOVESPA during the period of January 1st 2007 to July 29th 2011, in consequence of the financial crisis occurred in 2008. Traditional techniques were employed in Finance and Econometrics knowledge to analyze the impacts of this crisis on the Brazilian banking sector, based on the daily closing prices of the shares of major Brazilian banks, includes Banco do Brasil, Bradesco, Itaà and IBOVESPA. The methodology used was based on the model of asset pricing, CAPM, in the measurement of systemic risk. It was observed that the statistical evidence, gained with the Chow test and t test for averages differences, basically indicate that it was possible to capture a different effect during the 2008âs crisis between public bank and private banks in relation to systemic risk, and capture a structural change in October 24, 2008, a shift detected from the Chow test.

This paper analyzes how the COVID-19 pandemic has affected the Swedish housing market, and in particular prices and shifts in trends. Different classes of housing objects in various counties are investigated. Combining web scraped housing data for the entirety of Sweden between 2016-01-01 and 2021-03-31, including economic, demographic, socioeconomic and locational data, a hedonic regression model is used to estimate how different variables influence the housing price. The base model is subsequently used to investigate if statistically significant structural breaks exist in relation to the COVID-19 pandemic for the different object types in the entire Swedish market and in certain specific counties. Structural breaks are found for the housing object types ‘Fritidshus’, ‘Lägenhet’ and ‘Radhus’ in the entire Swedish market and for “Villa” in Stockholm county shortly after the pandemic outbreak, suggesting there is evidence for a pandemic infused shift in housing price regime on the Swedish housing market for these object types in stated areas. Splitting the hedonic regression model into three, one pooled regression, one before and one after the identified breaks, and comparing the shifts in impact of the housing price determinants suggests different pandemic effects on different object types. The result indicates that for the object types ‘Lägenhet’ in the entire country and for ‘Villa’ in Stockholm county, living area has an increased impact on the price while the locational variable population density has a decreased impact after the breakpoint date compared to before. This could suggest that for permanent housing objects in these regions, living area might have become increasingly valued over location during the pandemic. The results further indicate the direct opposite effect on the shifted impact in living area and the population density for the price of the temporary housing type Fritidshus in entire Sweden. However, an indication for increased impact of the areas socioeconomic level is noted for all these three object types. These results hold as a ground for further research in the subject.

The global financial crisis that started in the USA affected several countries around the world. This study focuses on only three countries; the USA, Sweden, and Italy, which are examples of economies with three different labor market models. The purpose of this study is to investigate if and in that case how Okun's law was affected by the global financial crisis in the three countries’ labor market models and if there are any differences in the correlations before and after the global financial crisis. Okun’s difference version was used in this study. Quarterly time series data was used in this study during the time period 1985-2019. The Chow test was used to test the hypothesis. The results show that the global financial crisis affected Okun’s law after the crisis in all three countries. The USA, Sweden, and Italy were affected differently

[pt] O objetivo desta dissertação é propor um mecanismo de testes para a avaliação dos resultados obtidos em uma modelagem TS-TARX.A principal motivação é encontrar uma solução para um problema comum na modelagem TS-TARX : os modelos espúrios que são gerados durante o processo de divisão do espaço das variáveis independentes.O modelo é uma heurística baseada em análise de árvore de regressão, como discutido por Brieman -3, 1984-. O modelo proposto para a análise de séries temporais é chamado TARX - Threshold Autoregressive with eXternal variables-. A idéia central é encontrar limiares que separem regimes que podem ser explicados através de modelos lineares. Este processo é um algoritmo que preserva o método de regressão por mínimos quadrados recursivo -MQR-. Combinando a árvore de decisão com a técnica de regressão -MQR-, o modelo se tornou o TS-TARX -Tree Structured - Threshold AutoRegression with external variables-.Será estendido aqui o trabalho iniciado por Aranha em -1, 2001-. Onde a partir de uma base de dados conhecida, um algoritmo eficiente gera uma árvore de decisão por meio de regras, e as equações de regressão estimadas para cada um dos regimes encontrados. Este procedimento pode gerar alguns modelos espúrios ou por construção,devido a divisão binária da árvore, ou pelo fato de não existir neste momento uma metodologia de comparação dos modelos resultantes.Será proposta uma metodologia através de sucessivos testes de Chow -5, 1960- que identificará modelos espúrios e reduzirá a quantidade de regimes encontrados, e consequentemente de parâmetros a estimar. A complexidade do modelo final gerado é reduzida a partir da identificação de redundâncias, sem perder o poder preditivo dos modelos TS-TARX .O trabalho conclui com exemplos ilustrativos e algumas aplicações em bases de dados sintéticas, e casos reais que auxiliarão o entendimento. / [en] The goal of this dissertation is to propose a test mechanism to evaluate the results obtained from the TS-TARX modeling procedure.The main motivation is to find a solution to a usual problem related to TS-TARX modeling: spurious models are generated in the process of dividing the space state of the independent variables.The model is a heuristics based on regression tree analysis, as discussed by Brieman -3, 1984-. The model used to estimate the parameters of the time series is a TARX -Threshold Autoregressive with eXternal variables-.The main idea is to find thresholds that split the independent variable space into regimes which can be described by a local linear model. In this process, the recursive least square regression model is preserved. From the combination of regression tree analysis and recursive least square regression techniques, the model becomes TS-TARX -Tree Structured - Threshold Autoregression with eXternal variables-.The works initiated by Aranha in -1, 2001- will be extended. In his works, from a given data base, one efficient algorithm generates a decision tree based on splitting rules, and the corresponding regression equations for each one of the regimes found.Spurious models may be generated either from its building procedure, or from the fact that a procedure to compare the resulting models had not been proposed.To fill this gap, a methodology will be proposed. In accordance with the statistical tests proposed by Chow in -5, 196-, a series of consecutive tests will be performed.The Chow tests will provide the tools to identify spurious models and to reduce the number of regimes found. The complexity of the final model, and the number of parameters to estimate are therefore reduced by the identification and elimination of redundancies, without bringing risks to the TS-TARX model predictive power.This work is concluded with illustrative examples and some applications to real data that will help the readers understanding.

相關研究指出土地面積與地價應該呈現非線性關係，隨著坵塊面積增加，土地價格將先以遞增的速率增加，之後再以遞減的速率增加，即基地面積規模不經濟（plattage）和基地面積規模經濟（plottage）現象。本研究以台南市土地交易案例進行驗證，以總價模型利用「移動式Chow Test」尋找結構變化點，據以分析其經濟結構是否具有顯著差異。實證結果顯示基地面積規模經濟(plottage)與基地面積規模不經濟(plattage)現象同時存在。 / According to some literature, there is a nonlinear relationship between the land area and the land value. Land value will enhance with an increasing pace as land area increase in the beginning. However, as land area keeps increasing, the land value will only enhance with a decreasing pace. Namely, the plattage phenomenon will follow the plottage phenomenon. Bases on the land transaction samples from Tainan city and the model with total price as dependent variable, this research searches the structural change of the land area using Chow Test sequence to analyze whether there is significant distinction in economic structure. The empirical results show the plattage phenomenon coexists with the plottage phenomenon.

O objetivo específico da presente dissertação é estimar a elasticidade-PIB do Imposto de Renda Pessoa Física (IRPF) e Imposto Renda Pessoa Jurídica (IRPJ) no Brasil entre 1986 e 2012. A pesquisa também incorpora em seus objetivos uma análise técnica a respeito da tributação e seus impactos sobre o sistema econômico, tanto a nível microeconômico e macroeconômico, além de abordar o IRPF e IRPJ em seu aspecto econômico e jurídico. No tratamento metodológico são utilizados modelos de Vetor de Correção de erros (VEC) para estimar as elasticidades-PIB do IRPF e IRPJ. Os resultados apontam uma elasticidade-PIB, tanto para IRPF quanto IRPJ, acima da unidade, na maioria dos modelos estimados, e existem períodos determinados que impactam consideravelmente sobre à arrecadação desses tributos. / This dissertation estimates the GDP elasticity of income tax revenue for individuals (IRPF) and corporations (IRPJ) between 1986 and 2012. Additionally the research incorporates an analysis of the macroeconomic and microeconomic effects of taxation. IRPF and IRPJ are analyzed in great detail, including economic as well as legal aspects. An Error Correction Model is estimated to obtain the elasticities. The results show that both elasticities are higher than unit and that reforms that took place in some periods have a significant impact on tax collection.

O objetivo específico da presente dissertação é estimar a elasticidade-PIB do Imposto de Renda Pessoa Física (IRPF) e Imposto Renda Pessoa Jurídica (IRPJ) no Brasil entre 1986 e 2012. A pesquisa também incorpora em seus objetivos uma análise técnica a respeito da tributação e seus impactos sobre o sistema econômico, tanto a nível microeconômico e macroeconômico, além de abordar o IRPF e IRPJ em seu aspecto econômico e jurídico. No tratamento metodológico são utilizados modelos de Vetor de Correção de erros (VEC) para estimar as elasticidades-PIB do IRPF e IRPJ. Os resultados apontam uma elasticidade-PIB, tanto para IRPF quanto IRPJ, acima da unidade, na maioria dos modelos estimados, e existem períodos determinados que impactam consideravelmente sobre à arrecadação desses tributos. / This dissertation estimates the GDP elasticity of income tax revenue for individuals (IRPF) and corporations (IRPJ) between 1986 and 2012. Additionally the research incorporates an analysis of the macroeconomic and microeconomic effects of taxation. IRPF and IRPJ are analyzed in great detail, including economic as well as legal aspects. An Error Correction Model is estimated to obtain the elasticities. The results show that both elasticities are higher than unit and that reforms that took place in some periods have a significant impact on tax collection.