Made available in DSpace on 2016-06-02T20:04:51Z (GMT). No. of bitstreams: 1 4040.pdf: 1510214 bytes, checksum: 7dfe4542c20ffa8a47309738bc22a922 (MD5) Previous issue date: 2011-12-16 / Financiadora de Estudos e Projetos / The application of a gold standard reference test in all or part of the sample under investigation is often not feasible for the majority of diseases affecting humans, either by a lack of consensus on which testing may be considered a gold standard, the high level of invasion of the gold standard technique, the high cost of financially large-scale application, or by ethical questions, so to know the performance of existing tests is essential for the process of diagnosis of these diseases. In statistical modeling aimed to obtain robust estimates of the prevalence of the disease (x ) and the performance parameters of diagnostic tests (sensitivity (Se) and specificity (Sp)), various strategies have been considered such as the stratification of the population, the relaxation of the assumption of conditional independence, the inclusion of covariates, the verification type (partial or total) and the techniques to replace the gold standard. In this thesis we propose a new structure of stratification of the population considering both the prevalence rates and the parameters of test performance among the different strata (EHW). A Bayesian latent class modeling to estimate these parameters was developed for the general case of K diagnostic tests under investigation, relaxation of the assumption of conditional independence according to the formulations of the fixed effect (FECD) and random (RECD) with dependent order (h _ k) and M covariates. The application of models to two data sets about the performance evaluation of diagnostic tests used in screening for Chagas disease in blood donors showed results consistent with the sensitivity studies. Overall, we observed for the structure of stratification proposal (EHW) superior performance and estimates closer to the nominal values when compared to the structure of stratification when only the prevalence rates are different between the strata (HW), even when we consider data set with rates of Se, Sp and x close among the strata. Generally, the structure of latent class, when we have low or high prevalence of the disease, estimates of sensitivity and specificity rates have higher standard errors. However, in these cases, when there is high concordance of positive or negative results of the tests, the error pattern of these estimates are reduced. Regardless of the structure of stratification (EHW, HW), sample size and the different scenarios used to model the prior information, the model of conditional dependency from the FECD and RECD had, from the information criteria (AIC, BIC and DIC), superior performance to the structure of conditional independence (CI) and to FECD with improved performance and estimates closer to the nominal values. Besides the connection logit, derived from the logistic distribution with symmetrical shape, find in the link GEV, derived from the generalized extreme value distribution which accommodates symmetric and asymmetric shapes, a interesting alternative to construct the conditional dependence structure from the RECD. As an alternative to the problem of identifiability, present in this type of model, the criteria adopted to elicit the informative priors by combining descriptive analysis of data, adjustment models from simpler structures, were able to produce estimates with low standard error and very close to the nominal values. / Na área da saúde a aplicação de teste de referência padrão ouro na totalidade ou parte da amostra sob investigação é, muitas vezes, impraticável devido à inexistência de consenso sobre o teste a ser considerado padrão ouro, ao elevado nível de invasão da técnica, ao alto custo da aplicação em grande escala ou por questões éticas. Contudo, conhecer o desempenho dos testes é fundamental no processo de diagnóstico. Na modelagem estatística voltada à estimação da taxa de prevalência da doença (x ) e dos parâmetros de desempenho de testes diagnósticos (sensibilidade (S) e especificidade (E)), a literatura tem explorado: estratificação da população, relaxamento da suposição de independência condicional, inclusão de covariáveis, tipo de verificação pelo teste padrão ouro e técnicas para substituir o teste padrão ouro inexistente ou inviável de ser aplicado em toda a amostra. Neste trabalho, propomos uma nova estrutura de estratificação da população considerando taxas de prevalências e parâmetros de desempenho diferentes entre os estratos (HWE). Apresentamos uma modelagem bayesiana de classe latente para o caso geral de K testes diagnósticos sob investigação, relaxamento da suposição de independência condicional segundo as formulações de efeito fixo (DCEF) e efeito aleatório (DCEA) com dependência de ordem (h _ K) e inclusão de M covariáveis. A aplicação dos modelos a dois conjuntos de dados sobre avaliação do desempenho de testes diagnósticos utilizados na triagem da doença de Chagas em doadores de sangue apresentou resultados coerentes com os estudos de sensibilidade. Observamos, para a estrutura de estratificação proposta, HWE, desempenho superior e estimativas muito próximas dos valores nominais quando comparados à estrutura de estratificação na qual somente as taxas de prevalências são diferentes entre os estratos (HW), mesmo quando consideramos dados com taxas de S, E e x muito próximas entre os estratos. Geralmente, na estrutura de classe latente, quando temos baixa ou alta prevalência da doença, as estimativas das sensibilidades e especificidades apresentam, respectivamente, erro padrão mais elevado. No entanto, quando há alta concordância de resultados positivos ou negativos, tal erro diminui. Independentemente da estrutura de estratificação (HWE, HW), do tamanho amostral e dos diferentes cenários utilizados para modelar o conhecimento a priori, os modelos de DCEF e de DCEA apresentaram, a partir dos critérios de informação (AIC, BIC e DIC), desempenhos superiores à estrutura de independência condicional (IC), sendo o de DCEF com melhor desempenho e estimativas mais próximas dos valores nominais. Além da ligação logito, derivada da distribuição logística com forma simétrica, encontramos na ligação VEG , derivada da distribuição de valor extremo generalizada a qual acomoda formas simétricas e assimétricas, interessante alternativa para construir a estrutura de DCEA. Como alternativa ao problema de identificabilidade, neste tipo de modelo, os critérios para elicitar as prioris informativas, combinando análise descritiva dos dados com ajuste de modelos de estruturas mais simples, contribuíram para produzir estimativas com baixo erro padrão e muito próximas dos valores nominais.

Este trabalho presta-se a analisar a adequação da execução da política monetária pelos Bancos Centrais, com enfoque especial dado ao Banco Central do Brasil e ao arcabouço normativo atualmente em vigor sobre a matéria. A necessidade de desenvolver este tema sobreveio da verificação, especialmente nas duas últimas décadas, de um distanciamento dos Bancos Centrais em relação às orientações do Poder Executivo. O regime de metas inflacionárias, tido como o ideal para orientar a atuação dos Bancos Centrais e assegurar a estabilidade da moeda foi assumido como o objetivo-fim da política monetária, em detrimento das previsões constitucionais acerca da promoção do desenvolvimento equilibrado do País, da busca do pleno emprego e da redução das desigualdades sociais. Para a análise desenvolvida, partiu-se do método histórico, por meio do qual foi possível verificar, a partir do Século XIX até o presente, de que forma os Bancos Centrais surgiram e galgaram posições de relevo enquanto agentes do Estado orientados a intervir na economia para fins de promoção social, especialmente a partir do surgimento e consolidação do Direito Econômico como ciência jurídica legitimadora da intervenção estatal. Em seguida, buscou-se explorar as funções dos Bancos Centrais, os instrumentos dos quais dispõem para o exercício da política monetária e a adequação dos objetivos dessa política no contexto da política econômica desenvolvida pelo Estado. Por fim, passou-se à análise do Banco Central do Brasil no que concerne a evolução da execução da política monetária, paralelamente às conquistas sociais e políticas do país, com especial destaque para as décadas de 1960 e 1990. / This work is to examine the appropriateness of implementing monetary policy by central banks, with particular emphasis given to the Central Bank of Brazil and the regulatory framework currently in force on the matter. The need to develop this theme came to check, especially in the last two decades, from a distance of central banks in relation to Executive guidelines. Inflation targeting system, seen as the ideal to drive central banks actions and ensure currency stability was adopted as the end goal of monetary policy at the expense of constitutional statements upon balanced development of the country, in pursuit of comprehensive employment and the reduction of social inequalities. For the developed analysis, historical method has been adopted which enabled the understanding from the nineteenth century until present days upon how Central Banks emerged and have risen to prominent positions as agents of the Stated driven to intervene in economy for social advancement, especially since the emergence and consolidation of Economic Law and legal science legitimating state intervention. Then Central Banks central banks functions were explored, theirs tools for monetary policy undertaking and the adequacy of such objectives in the context of economic policy developed by the state. Finally, we have assessed Brazil Central Bank in regards of monetary policy implementation development, along with social and political local achievements, with particular emphasis to the 60s and 90s.

Ma thèse étudie la pensée monétaire ainsi que les travaux de Ralph G. Hawtrey, Harry D. White et Robert Triffin, entre 1919 et 1960. Au cours des débats sur cette période, considérée comme fondatrice pour le système monétaire international, ces trois économistes ont été des personnalités clés qui ont influencé le cours de l’histoire monétaire. Premièrement, ils ont critiqué la théorie de l’étalon-or issue de la tradition ricardienne, en soulignant le caractère non-automatique et asymétrique du mécanisme d’ajustement de la balance des paiements. En s’articulant autour du rejet de cette tradition, les analyses de nos auteurs ont caractérisé les faiblesses liées au fonctionnement du système monétaire international. Deuxièmement, bénéficiant de leurs positions au Trésor américain et britannique, au FMI ou encore à la Fed, ces économistes ont exercé une influence sur les réformes en œuvrant pour une consolidation de la coopération monétaire internationale dans un régime de changes fixes. / My PhD dissertation studies Ralph G. Hawtrey’s, Harry D. White’s and Robert Triffin’s monetary thought and works between 1919 and 1960. Actively participating to key institutions which shaped the international monetary system – the British Treasury for Hawtrey, the US Treasury for White and the Fed and the IMF in the case of Triffin – those economists influenced the course of monetary theory and history. They both wrote on the non-automatic and asymmetric nature of the balance of payments adjustment mechanism, and formulated an original critic towards the classical Ricardian gold standard theory. Structured around the rejection of this classical theory, the authors’ analysis pointed out the weaknesses of the international monetary system. Since then, all of their reform proposals were grounded on the strengthening of monetary cooperation under a fixed exchange rates system.

Este trabajo fue motivado por el creciente número de crisis financieras internacionales que se habían producido durante la última década (1995-2005) y por la ausencia de un modelo de referencia que pudiera explicar dichos fenómenos. El hecho básico es que estos son consecuencia de decisiones tomadas por agentes económicos. Cualquier decisión no sólo está basada en unos criterios estrictamente económicos sino que incorpora aspectos institucionales.Este trabajo ha tenido como propósito realizar un estudio sobre la incidencia de las instituciones (en el sentido definido por Douglass North) durante la resolución y gestión de una crisis financiera de origen cambiario. Este estudio se inscribe dentro de una corriente de investigaciones en del campo de la Economía Política de las crisis financieras y pretende ser una aportación que permita ampliar el conocimiento actual adentrándose en el terreno institucional y en la toma de decisiones.El análisis ha consistido en un estudio de caso con las siguientes premisas: tres momentos históricos distintos, y por tanto unas instituciones distintas, tanto a nivel mundial (existencia de tres órdenes distintos) como a nivel interno; tres regímenes de tipo de cambio distintos, aunque compartan como característica principal un grado de fijación considerable; y que han sido sacudidos por tres crisis financieras diferentes. Esas características comunes conducían a circunscribir la investigación a un determinado territorio. La elección recayó sobre un país "eternamente fascinante": Argentina.La conclusión principal es que el Sistema Monetario Internacional ha funcionado relativamente bien cuando todos los actores se atenían las mismas instituciones informales. Si se daba este requisito, las sucesivas crisis se superaban elaborando nuevas instituciones formales u organizaciones y el enforcement no era necesario. En el caso contrario, la creación de nuevas instituciones formales u organizaciones no tenían efecto alguno y toda la presión del mundo no frenaba la crisis, a lo sumo, la retardaba con los consecuentes efectos negativos sobre la economía real. Por tanto, las instituciones informales son un elemento fundamental en su influencia sobre los regimenes de tipo de cambio.

I evaluate four possible approaches the United States may take to address China's practice of undervaluing the renminbi: 1) a challenge under Article XV of the GATT and the associated IMF provisions; 2) countervailing duties; 3) antidumping measures; and 4) safeguard measures. I conclude that the first three approaches are unlikely to succeed; there are a number of legal and political obstacles to the pursuit of these remedies. While the current WTO safeguards regime is likely insufficient, a new safeguards regime can--and should--be developed. I review and critique Dani Rodrik's proposal for a new safeguards regime and set out my own basic blueprint for a significantly expanded safeguards regime, emphasizing that flexibility in the realm of international trade law would help to secure overall stability in international trade itself. In order to be effective shock absorbers, safeguards must become far more flexible.

I evaluate four possible approaches the United States may take to address China's practice of undervaluing the renminbi: 1) a challenge under Article XV of the GATT and the associated IMF provisions; 2) countervailing duties; 3) antidumping measures; and 4) safeguard measures. I conclude that the first three approaches are unlikely to succeed; there are a number of legal and political obstacles to the pursuit of these remedies. While the current WTO safeguards regime is likely insufficient, a new safeguards regime can--and should--be developed. I review and critique Dani Rodrik's proposal for a new safeguards regime and set out my own basic blueprint for a significantly expanded safeguards regime, emphasizing that flexibility in the realm of international trade law would help to secure overall stability in international trade itself. In order to be effective shock absorbers, safeguards must become far more flexible.

Diese Dissertation besteht aus einer Einleitung und drei empirischen Kapiteln, die sich mit verschiedenen Aspekten der Offenmarktgeschäfte der Bank of England in der Zwischenkriegszeit befassen. Offenmarktgeschäfte sind der Kauf und Verkauf von kurzfristigen Staatsanleihen. Die Einleitung definiert Instrumente und Ziele der Geldpolitik und beschreibt welche Folgen die veränderte Rolle Großbritanniens in der Welt nach dem 1. Weltkrieg für die Geldpolitik hatte. Das zweite Kapitel zeigt, wie Offenmarktgeschäfte die verfügbare Liquidität auf dem Londoner Geldmarkt erhöhen oder senken können. Dies erlaubt die kurzfristigen Marktzinsen relativ zum Leitzins zu steuern, was wiederum häufige Änderungen der Leitzinsen unnötig machte. Die empirische Analyse zeigt, dass Offenmarktgeschäfte die Wahrscheinlichkeit verändern können, dass Marktteilnehmer sich Geld bei der Diskontfazilität leihen müssen. Das dritte Kapitel zeigt, dass Offenmarktgeschäfte noch weitere Zwecke erfüllen. In der Finanzkrise von 1931 trugen Offenmarktgeschäfte dazu bei die größten Geschäftsbanken in London vor größerem Schaden zu bewahren. Der Verlust von Goldreserven wurde durch Offenmarktgeschäfte in großem Maße kompensiert und stabilisierte so die Liquidität der Geschäftsbanken. Das vierte Kapitel zeigt, dass Offenmarktgeschäfte zudem eine entscheidende Rolle bei der Stabilisierung der kurzfristigen Marktzinsen nach Kriegsausbruch 1939 spielten. Die empirische Analyse zeigt wie sorgfältig gewählte Laufzeiten von Offenmarktgeschäften dazu beigetragen haben, übermäßige Schwankungen der kurzfristigen Marktzinsen zu verhindern. Insgesamt deutet diese Dissertation darauf hin, dass die Bank of England in der Zwischenkriegszeit ähnlich einer modernen Zentralbank agierte. Kurzfristige Marktzinsen waren das operatives Ziel der Geldpolitik und nicht die Zentralbankgeldmenge. Im Jahr 1931 zog die Bank of England es vor die Geschäftsbanken zu stützen, auch wenn dies die Aufgabe des festen Wechselkurses bedeutete. / This dissertation consists of an introductory chapter and three empirical chapters which deal with various aspects of open-market operations by the Bank of England during the interwar period. Open-market operations are the purchase and sale of Treasury bills. The introduction defines monetary policy implementation and describes the economic circumstances after World War I and outlines what consequences the changing role of Britain in the world had for monetary policy. The second chapter shows how open-market operations could add or drain liquidity in the London money market and help steer short-term market rates relative to the Bank rate, which made frequent changes in the Bank Rate unnecessary. The empirical analysis shows that open-market operations could change the probability of market participants having to borrow at the discount facility. The third chapter argues that in time of crisis the purpose of open-market operations goes further. During the financial crisis of 1931 open-market operations most likely helped to protect the largest clearing banks in London from severe harm. The empirical analysis shows how open-market operations offset the effect of reserves losses at an unprecedented scale and stabilized the liquidity of the London clearing banks. Chapter four examines the role of open-market operation after the outbreak of war in 1939. Open-market operations played a crucial role in stabilizing short-term market rates and preserving the London money market in its original form, most notably the London discount houses and clearing banks. The descriptive evidence shown suggests how carefully chosen maturities of open-market operations helped offset any undue disturbances to short-term market rates after the outbreak of war. Overall, this dissertation suggests that the Bank of England, not unlike modern central banks, targeted short-term market rates, not some monetary quantity, and chose banking stability over a fixed exchange rate in 1931.

“The Purloined Letter,” Edgar Allan Poe's third and final tale featuring the detective Dupin, has evoked a long history of critical response. Criticism has tended to read the text for its role in the development of detective fiction and as illustrative of various theoretical positions. However, the implications of the “The Purloined Letter,” as a tale of ratiocination, has largely been left unexplored. “The Purloined Letter” explores logical processes of value and exchange, particularly economic exchange, in a manner very similar to what Charles Sanders Peirce will call pragmatism several decades later. Dupin's deductive methods and Peirce's abductive logic express the nature of objects in terms of social systems of preference and perception rather metaphysics. Peirce's classification of signs as icon, index, or symbol provides a framework of signification which can be read in conjunction with “The Purloined Letter” to flesh out the role of materiality and value in the theory of economic criticism. Reading value and exchange as part of a social system of signs, perceptions, and representations of value will serve to expose a penchant for material fetishism in economic criticism and provide a theory of currency, value, and exchange that contextualizes representational and material notions of value within the social and economic system that provides the processes and mechanisms of value determination. The way that the Prefect, the Minister D___, and Dupin each conceptualize the purloined letter as having a different representational relationship with value can be used to demonstrate Poe's abductive framework for economy.