This thesis has two parts, each with a different subject. Part 1 studies the macroeconomic implications of alternative health care reforms. Part 2 studies the computation and simulation of dynamic competitive equilibria in models with heterogeneous agents and market frictions. In 2007, 44.5 million non-elderly in the U.S did not have health insurance coverage. Empirical studies suggest that there are serious negative consequences associated with uninsurance. Consequently, there is wide agreement that reforming the current health care system is desirable and several proposals have been discussed among economists and in the political arena. However, little attention has been paid to quantify the macroeconomic consequences of reforming the health insurance system in the U.S. The objective of this section is to develop a theoretical framework to evaluate a broad set of health care reform plans. I build a model that is capable of reproducing a set of key facts of health expenditure and insurance demand patterns, as well as key macroeconomic conditions of the U.S. during the last decade. Then, I use this model to derive the macroeconomic implications of alternative reforms and alternative ways of funding these reforms. The second part of this thesis studies the computation and simulation of dynamic competitive equilibria in models with heterogeneous agents and market frictions. This type of models have been of considerable interest in macroeconomics and finance to analyze the effects of various macroeconomic policies, the evolution of wealth and income distribution, and the variability of asset prices. However, there is no reliable algorithm available to compute their equilibria. We develop a theoretical framework for the computation and simulation of dynamic competitive markets economies with heterogeneous agents and market frictions. We apply these methods to some macroeconomic models and find important improvements over traditional methods.

In this dissertation, I study the influence of monitoring by institutional investors on corporate behavior within the context of CEO compensation-based incentives. I find that institutional investors provide an executive with higher levels of compensation sensitivity with respect to a firm’s equity price (Delta). In contrast to prior literature, however, once I control the dynamic nature of the data, institutional investors do not affect compensation sensitivity with respect to a firm’s equity risk (Vega). Instead, I find that institutional investors appear to influence the risk profile of firm through the firm’s investment, financing and diversification policy choices even after I control for the CEO’s compensation structure. The results suggest that compensation-related incentives to increase risk (i.e. vega) and monitoring by institutional investors are substitutes of each other in that both can offset the managerial incentives to reduce risk that stem from greater levels of compensation delta. These results are robust to potential endogeneity problems that may arise due to the dynamic nature of panel data.

Multi-agent models are software models of real systems, which are compounded of a large amount of active autonomous units -- agents. The main theme of this study is the application of multi-agent models in economics. In the first part of this study I synthesized information from many sources and created a proposal of methodology of multi-agent modeling in social sciences. This methodology is illustrated by a detailed analysis of a well-known model of ethnocentric behavior. I focused on the issue of complexity a self-organization a observed the development of different kinds of structural complexity. Another important issue I'm dealing with is the relation between multi-agent models and analytical models used by the mainstream economy The second part contains three applications of multi-agent models in economy. All described models are research models -- the aim is to get insight into the fundamental laws controlling the dynamics of the system. Research models should be as simple as possible -- than we can understand how the behavior of the system is resulting from the interaction of agents. All models represent an alternative to some typical economic situation. The alternative consists mainly in abandoning of the assumption of full rationality of agents. I focused on models with reactive agents, which don't dispose any memory (or only an indirect form of memory) and have no ability of complex symbolical representation of the environment. Reactivity of agents doesn't necessarily mean an unwanted limitation. It could be properly used to model different kinds of bounded rationality. The model of transaction costs on financial markets is based on another model, which showed how the instability of the financial market could result from interactions of agents with bounded rationality. The instability of the financial markets contradicts the Effective Markets Hypothesis. I modified and extended this model with the mechanism of transaction cost. The model shows that higher transaction costs lead to greater stability of the market, they decrease the volume of trade and to some extent they can increase the efficiency of the modeled market. The model of evolution of aversion to risk and ambiguity is inspired by psychological and neurological experiments whose results contradict the Expected Utility Hypothesis. Model shows that there exists very simple mechanism which leads to evolution of risk and ambiguity aversion. This aversion evolves because of situations when the agent can repeatedly decide between two choices, one brings him low but risk free utility, second brings him higher utility which involves the risk that the agent will lose its ability to get any utility in the future (e.g. it will die). The model shows that sexual reproduction strengthens this mechanism. If this mechanism has also evolved in humans, it can influence their behavior and lead to "irrational" behavior contradicting the Expected utility hypothesis. The model of monopsony on the labor market analyses the situation in which the employer could cut the wages to the existential minimum of workers. In such a case are the workers paradoxically to increase the labor supply when the wages are decreasing. The model further analyses the influence of consumer loans on the profit of the employer, unemployment and welfare. The model shows that the increasing of the probability of consumer loans increases the profits, increases unemployment, decreases well-fare and in some situations it enables the employer to decrease the wages to the existential minimum. The model also suggests that for very low wages the decrease of minimum wage could lead to increase of unemployment. From the results recommendations could be obtained both for the profit maximizing employer and for the workers resisting the wage cuts.

abstract: Environmental agencies often want to accomplish additional objectives beyond their central environmental protection objective. This is laudable; however it begets a need for understanding the additional challenges and trade-offs involved in doing so. The goal of this thesis is to examine the trade-offs involved in two such cases that have received considerable attention recently. The two cases I examine are (1) the protection of multiple environmental goods (e.g., bundles of ecosystem services); and (2) the use of payments for ecosystem services as a poverty reduction mechanism. In the first case (chapter 2), I build a model based on the fact that efforts to protect one environmental good often increase or decrease the levels of other environmental goods, what I refer to as "cobenefits" and "disbenefits" respectively. There is often a desire to increase the cobenefits of environmental protection efforts in order to synergize across conservation efforts; and there is also a desire to decrease disbenefits because they are seen as negative externalities of protection efforts. I show that as a result of reciprocal externalities between environmental protection efforts, environmental agencies likely have a disincentive to create cobenefits, but may actually have an incentive to decrease disbenefits. In the second case (chapter 3), I model an environmental agency that wants to increase environmental protection, but would also like to reduce poverty. The model indicates that in theory, the trade-offs between these two goals may depend on relevant parameters of the system, particularly the ratio of the price of monitoring to participant's compliance cost. I show that when the ratio of monitoring costs to compliance cost is higher, trade-offs between environmental protection and poverty reduction are likely to be smaller. And when the ratio of monitoring costs to compliance costs is lower, trade-offs are likely to be larger. This thesis contributes to a deeper understanding of the trade-offs faced by environmental agencies that want to pursue secondary objectives of protecting additional environmental goods or reducing poverty. / Dissertation/Thesis / M.S. Biology 2012

Les logiques multivalentes sont définies comme une famille de logiques non classiques dont la caractéristique commune est de ne pas restreindre les valeurs de vérité aux seuls « vrai » et « faux ». À cet égard, Kleene (1938) a offert une logique se fondant sur l’intuition que tout énoncé est soit vrai, soit faux ; mais qu’il existe néanmoins des énoncés dont la valeur de vérité n’est pas connue. La formalisation d’une telle intuition amena Kleene à introduire une troisième attribution de valeur de vérité pour les énoncés : « inconnu ». Pour autant, une telle formalisation reste ambiguë : elle échoue à résoudre la dichotomie entre le fait que tout énoncé est soit vrai, soit faux et le fait qu’il existe des énoncés dont l’attribution de valeur de vérité n’est ni « vrai », ni « faux ». L’enjeu de la présente thèse sera l’introduction d’une nouvelle logique multivalente intitulée logique de l’agent rationnel se fondant sur les idées de Kleene tout en en éliminant l’ambiguïté décrite plus haut.La logique de l’agent rationnel permet de modéliser le raisonnement d’un agent en considérant la connaissance (ou l’ignorance) qu’il peut avoir de la valeur de vérité classique des énoncés. D’un point de vue technique, nous introduisons plusieurs définitions de la notion de conséquence logique dans ce cadre, et construisons sur cette base, des sémantiques complètes de notre logique. Nous montrons ensuite l’intérêt d’une telle formalisation en l’appliquant à l’étude d’un problème épistémologique connu sous le nom de « paradoxe de la connaissabilité ». D’un point de vue épistémologique, l’introduction de la logique de l’agent rationnel permet d’analyser la notion d’ignorance comme indépendante de celle de connaissance. Une telle formalisation ouvre ainsi la voie à une position inédite, selon laquelle la notion d’ignorance est primitive et non analysable. / Many-valued logics is a family of non-classical logics, which is characterized by the fundamental fact that they do not restrict the truth values to only truth and falsity. According to this line of inquiry, Kleene (1938) constructed a logic that is based on the idea that every proposition is either true, or false, but there exist propositions for which the truth value is unknown. The formalisation of this idea leads to the introduction of a third assignment of truth value to propositions, interpreted as “unknown”. However, this formalisation contains an ambiguity, because it does not permit the resolution of a contradiction between the fact that every proposition is either true or false, and the fact that there exist propositions for which the assignment of truth value is neither “true” nor “false”. The initial aim of the present thesis is to explore Kleene’s idea in order to introduce and analyse a new many-valued logic, to be called the logic of a rational agent, that is founded on Kleene’s ideas, but that eliminates the above-mentioned ambiguity.The logic of a rational agent models the reasoning of an agent, taking into account the knowledge (or ignorance) of the classical truth value of a proposition that the agent can have. On the technical level, we introduce diverse definitions of entailment relations and construct consistent and complete semantics on this base. We then show the interest inherent in such a formalisation, by proposing an application of this logic to a famous epistemological problem, known as the “knowability paradox”. On the epistemological level, the logic of a rational agent permits us to offer an analysis of the notion of ignorance, as understood independently from the notion of knowledge. Such a formalization.

A dinâmica de crescimento populacional de uma espécie é permeada pela relação entre as desvantagens da competição intraespecífica e os benefícios da presença de conspecíficos. Para muitas espécies, os benefícios da cooperação podem superar as desvantagens da competição. A correlação positiva entre tamanho populacional e adaptabilidade em populações muito pequenas é conhecida como efeito Allee demográfico. Apesar de haver modelos matemáticos isolados para os diferentes tipos de efeitos Allee, não há um modelo simples que os abranja e os conecte a modelos de crescimento mais gerais (como o de Richards). Propomos unificar modelos de efeitos Allee e o de crescimento de Richards em um modelo que permita um novo ponto de vista sobre o efeito Allee demográfico. Um exemplo do aumento das possibilidades descritivas de tal generalização é a emergência de mais de uma transição cooperação-competição quando considerado um caso particular desse novo modelo (Allee-Gompertz). Apesar da importância do crescimento populacional, a maioria dos modelos básicos de transmissão de doenças infecciosas considera o tamanho populacional constante ou adota simplificações pouco plausíveis. Nesta tese, mostramos as deficiências de um modelo compartimental dinâmico de tuberculose já consagrado e propomos um novo modelo com crescimento populacional logístico. Quando comparados, nosso modelo apresenta previsões mais pessimistas para a erradicação da doença a longo prazo quando testado com parâmetros que definem políticas de controle pouco eficientes. Realizamos tais predições adotando estratégias de controle de países desenvolvidos e subdesenvolvidos. Visto que esses modelos compartimentais desprezam aspectos espaciais, desenvolvemos uma modelagem computacional de agentes, baseada no modelo proposto, com duas estruturas subjacentes: redes aleatórias e redes reais. A súbita emergência de tuberculose resistente a drogas como consequência de tratamentos ineficazes é também um resultado das implementações desses modelos em dois cenários distintos. Esses resultados são comparados com os do modelo compartimental e com os de um modelo de estrutura subjacente mais simples e, como novo resultado, surge nos dois modelos a possibilidade de erradicação da doença em menos de uma década após o início do tratamento. Esse resultado é possível desde que sejam adotadas estratégias eficientes de controle. / The one-species population growth dynamics is permeated by the relationship between the harms from the intraspecific competition and the benefits from the presence of conspecifics. For many species, the benefits from conspecific cooperation may outweigh the harms from competition. The positive correlation between population size and total fitness in very small population known as demographic Allee effect. Although there are isolated mathematical models for different types of Allee effects, there is not a simple model that covers and connects them to more general growth models (like Richards). We propose to unify models of Allee effects and the Richards growth one in a model that allows a new perspective on the demographic Allee effect. An example of the increased descriptive possibilities of such generalization is the emergence of more than one transition cooperation-competition when considering a particular case of this new model (Gompertz-Allee). Despite the importance of population growth, most basic models of infectious diseases transmission considers population size constant or adopts implausible simplifications. In this thesis, we show the shortcomings of a dynamic compartmental model of tuberculosis already established and we propose a new model with population logistic growth. When compared, our model provides more pessimistic forecasts for the eradication of the disease in the long term if it is tested with parameters that define inefficient control policies. We perform such predictions adopting control strategies from developed and underdeveloped countries. Since these compartmental model disregards spatial aspects, we developed a computational agent model, based on the proposed model, with two underlying structures: random networks and real networks. The sudden emergence of drug-resistant tuberculosis as a result of ineffective treatments is also a result from the implementations of these models in two distinct scenarios. These results are compared with the ones from a compartimental model and with the ones from a model with simpler underlying structure and, as a new result, the possibility of eradicating the disease in less than a decade after beginning the treatment appears on the two models. This result is possible adopting effective control strategies.

A dinâmica de crescimento populacional de uma espécie é permeada pela relação entre as desvantagens da competição intraespecífica e os benefícios da presença de conspecíficos. Para muitas espécies, os benefícios da cooperação podem superar as desvantagens da competição. A correlação positiva entre tamanho populacional e adaptabilidade em populações muito pequenas é conhecida como efeito Allee demográfico. Apesar de haver modelos matemáticos isolados para os diferentes tipos de efeitos Allee, não há um modelo simples que os abranja e os conecte a modelos de crescimento mais gerais (como o de Richards). Propomos unificar modelos de efeitos Allee e o de crescimento de Richards em um modelo que permita um novo ponto de vista sobre o efeito Allee demográfico. Um exemplo do aumento das possibilidades descritivas de tal generalização é a emergência de mais de uma transição cooperação-competição quando considerado um caso particular desse novo modelo (Allee-Gompertz). Apesar da importância do crescimento populacional, a maioria dos modelos básicos de transmissão de doenças infecciosas considera o tamanho populacional constante ou adota simplificações pouco plausíveis. Nesta tese, mostramos as deficiências de um modelo compartimental dinâmico de tuberculose já consagrado e propomos um novo modelo com crescimento populacional logístico. Quando comparados, nosso modelo apresenta previsões mais pessimistas para a erradicação da doença a longo prazo quando testado com parâmetros que definem políticas de controle pouco eficientes. Realizamos tais predições adotando estratégias de controle de países desenvolvidos e subdesenvolvidos. Visto que esses modelos compartimentais desprezam aspectos espaciais, desenvolvemos uma modelagem computacional de agentes, baseada no modelo proposto, com duas estruturas subjacentes: redes aleatórias e redes reais. A súbita emergência de tuberculose resistente a drogas como consequência de tratamentos ineficazes é também um resultado das implementações desses modelos em dois cenários distintos. Esses resultados são comparados com os do modelo compartimental e com os de um modelo de estrutura subjacente mais simples e, como novo resultado, surge nos dois modelos a possibilidade de erradicação da doença em menos de uma década após o início do tratamento. Esse resultado é possível desde que sejam adotadas estratégias eficientes de controle. / The one-species population growth dynamics is permeated by the relationship between the harms from the intraspecific competition and the benefits from the presence of conspecifics. For many species, the benefits from conspecific cooperation may outweigh the harms from competition. The positive correlation between population size and total fitness in very small population known as demographic Allee effect. Although there are isolated mathematical models for different types of Allee effects, there is not a simple model that covers and connects them to more general growth models (like Richards). We propose to unify models of Allee effects and the Richards growth one in a model that allows a new perspective on the demographic Allee effect. An example of the increased descriptive possibilities of such generalization is the emergence of more than one transition cooperation-competition when considering a particular case of this new model (Gompertz-Allee). Despite the importance of population growth, most basic models of infectious diseases transmission considers population size constant or adopts implausible simplifications. In this thesis, we show the shortcomings of a dynamic compartmental model of tuberculosis already established and we propose a new model with population logistic growth. When compared, our model provides more pessimistic forecasts for the eradication of the disease in the long term if it is tested with parameters that define inefficient control policies. We perform such predictions adopting control strategies from developed and underdeveloped countries. Since these compartmental model disregards spatial aspects, we developed a computational agent model, based on the proposed model, with two underlying structures: random networks and real networks. The sudden emergence of drug-resistant tuberculosis as a result of ineffective treatments is also a result from the implementations of these models in two distinct scenarios. These results are compared with the ones from a compartimental model and with the ones from a model with simpler underlying structure and, as a new result, the possibility of eradicating the disease in less than a decade after beginning the treatment appears on the two models. This result is possible adopting effective control strategies.

Worldwide income taxation in the country of residence is a legal dogma of international taxation. We question this dogma from the perspective of relations between developed and developing countries from a legal and economic perspective, and make a modern and fair proposal for tax treaties. We will show under which conditions a developing and a developed country will voluntarily sign a tax treaty where information is exchanged truthfully and whether they should share revenues. Moreover, we will demonstrate how the conclusion of a tax treaty can assist in the implementation of a tax audit system. / Series: WU International Taxation Research Paper Series

In this thesis, I apply the sophisticated tools made available by the econometrics of panel data and treatment models to a range of different issues. In the first Chapter, an ECM model is used to test on the existence of financing constraints in firms’ investment and R&D, taken a proxy for the efficiency of market institutions and governance rules in different countries. In the second chapter we test an agency model linking pay-performance contracts of CEOS to the financial situation of a firm by using a UK panel data. In the third chapter I use a sophisticated treatment model to evaluate the effectiveness of Italian public subsidies to R&D. Finally, in the fourth chapter I try to evaluate the efficiency of Italian regional systems of public healthcare by controlling for socio-economic factors and quality of healthcare in a composite model using panel data estimation and efficient frontier techniques.<p>The first Chapter analyzes the investment behavior of a sample of R&D intensive firms which are quoted on the stock market from USA, UK and Japan for the period 1990-1998. By using an error correction model we test the elasticity of investment and R&D to cash flow in these countries to see by which measure different market institutions and corporate governance rules affects the cost of external financing. Contrary to previous studies, we find significant differences in the sensitivity to cash flow of the two types of investment, with R&D expenditure being much less sensitive than ordinary investment. This is not surprising given the more long-term nature of R&D expenditures. For what concerns the comparison between the different systems/countries, the USA stock markets confirms as the most efficient market providing outside financing at a much lower cost compared to other markets, especially for young, smaller firms.<p>The second Chapter is a joint work with Biagio Speciale. It uses the data on a panel of quoted UK firms over the period 1995–2002 to study the effects of financial leverage on managerial compensation. The change in the investors’ expectations that caused the recent collapse of the stock market tech bubble is a perfect example of natural experiment that has been used as a source of plausibly exogenous variation in the firm’s debt. The estimates show that pay-for-performance sensitivity is increasing in financial leverage, with the exception of the 10% most levered firms, giving rise at the end to a non-linear (inverted U-shape) relationship between the two variables. The chapter includes also a theoretical model accounting for this relationship where an higher leverage increases both the expected returns and the expected variance of investment returns: the first effect (determining increased pay-performance sensitivity) prevails for low leverage values and the second effect (determining decreased pay-performance sensitivity) prevails for high leverage values.<p>The third Chapter undertakes an empirical estimation of the additionality of public funding on both the propensity to initiate R&D activity and the intensity of R&D spending of Italian enterprises for the period 1998-2000, using data from the Third Community Innovation Survey and from firms' financial accounts. The chosen methodology (Endogenous Switching Type II-Tobit) takes into account the possibility that decisions about both starting an R&D activity (sample selection effect) and applying for/obtaining public funding (essential heterogeneity) are influenced by private knowledge of enterprises' idiosyncratic propensities in R&D spending. The present analysis shows that both these effects are indeed important and that they contribute to explain most of the additionality found with less sophisticated models.<p>The fourth Chapter investigates the underlying causes of variability of public health expenditure per capita (SSPC henceforth) between Italian regions. A fixed-effect panel data estimate on the SSPC (for the period 1997-2006) is used in the first part of the paper to account for regional differences in terms of physical, demographic, socio-economic characteristics and in terms of other variables that affect demand and supply of health services. In the second part, we take the ‘adjusted’ SSPC and proceed to estimate an "efficient production function" of the quality of health services through Data Envelopment Analysis. This procedure allows us to separate the share of expenditure used for the improvement of the quality from the one that can be traced only to an inefficient use of financial resources. A comparison of regional SSPC after factoring out the socio-economic factors and the quality of healthcare shows that big differences still remain and are even exacerbated, signalling big pockets of inefficiency and correspondingly a huge potential for cost savings. Finally, a preliminary analysis shows a positive correlation between the efficiency of regional public spending in healthcare and the level of social capital. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished