This dissertation examines the effect of various corporate governance mechanisms on firm risk taking. The first essay examines the effect on firm risk through the CEO ability channel, while the second essay examines the effect on firm risk through the institutional investor channel. This first essay investigates CEO risk management ability. Using CEO education as a proxy for ability I examine the relationship between CEO education and various types of risk: (1) market risk, (2) credit risk, and (3) operational risk. Propensity score methods are used as a way to deal with the endogenous matching problem which exists in the executive compensation literature. These methods are proposed as an alternative to the managerial fixed effects approaches such as ``spell fixed effects'' and the mover dummy variable method (MDV). While the managerial fixed effects methods would fail when the explanatory variables of interest are time-invariant, it is possible to capture this variation in managerial effects by using propensity score methods. I find that the effect on the various types of risks varies by the type of risk and by the type and quality of education. Firms with CEOs that have law degrees and actuarial credentials are associated with fewer operational risk events. While firms with CEOs that have MBA degrees are able to manage market risk better than their peers. Overall, the quality of CEO education matters, and in many cases it is associated with a simultaneous reduction in firm risk and increase in firm value. This second essay investigates the impact of institutional shareholder ownership on firm risk taking. I find a negative relationship between the aggregate institutional ownership percentage and firm risk taking. I also find that institutional ownership concentration induces risk taking. In addition, the effect on firm risk is stronger when institutional shareholders have majority control. The results provide support for both the prudent-man law and the large institutional shareholder hypotheses. Furthermore, the results are robust to quasi-experimental approaches including propensity score matching and doubly robust estimation. These findings provide additional evidence on the benefits and incentives of institutional shareholder monitoring. / Business Administration/Risk Management and Insurance

The Cooperative Alleghany Bear Study (CABS) was initiated in 1994 to address concerns over the lack of biological and ecological data for black bear (Ursus americanus) populations in the Alleghany Mountains of western Virginia. I examined home range dynamics of bears during 1994-2002 on 2 study areas that were approximately 160 km apart. I analyzed my data with 3 home range programs (AMA, HRE, and ABODE) and determined the HRE was the least biased and produced the most biologically reasonable home range estimates. I used HRE to generate annual home ranges (fixed-kernel) for 90 bears over 160 bear years; I also generated seasonal home ranges using MCP. Annual and seasonal home ranges of male and female adult bears in the southern study area were larger than that of male and female adult bears in the northern study area, respectively; southern females and northern males had annual home ranges similar in size at the 95% and 75% fixed-kernel contours. In both study areas, most bears did not shift their range when transitioning from spring to summer (North: 63.0%; South: 57.0%) or from summer to fall (North: 67.0%; South: 65.0%), while most bears shifted their seasonal range between spring and fall (North: 67.0%; South: 52.0%). Most female bears in both study areas maintained the same spring and summer home range throughout the duration of the study, while 63% of northern females changed their fall home range and 55% of southern females maintained their fall home range. I found no differences in annual and seasonal home range size among years or among age classes for adult females, but tests for intra-year seasonal difference indicated that fall range was larger than spring and summer in 1997, when western Virginia experienced a poor mast crop. Females with and without COY had similar annual home ranges in either study area. In the north, seasonal home range size did not differ between females with and without COY, while in the south, breeding females (i.e. without COY) had larger spring ranges and smaller fall ranges than females with COY. In both study areas, females with COY had larger fall home ranges than during spring, while seasonal ranges of breeding females did not vary in size during the year. / Master of Science

This study investigated the performance of the three estimators of surplus production model including process-observation-error-estimator with normal distribution (POE_N), observation-error-estimator with normal distribution (OE_N), and process-error-estimator with normal distribution (PE_N). The estimators with fat-tailed distributions including Student's t distribution and Cauchy distribution were also proposed and their performances were compared with the estimators with normal distribution. This study used Bayesian method, revised Metropolis Hastings within Gibbs sampling algorithm (MHGS) that was previously used to solve POE_N (Millar and Meyer, 2000), developed the MHGS for the other estimators, and developed the methodologies which enabled all the estimators to deal with data containing multiple indices based on catch-per-unit-effort (CPUE). Simulation study was conducted based on parameter estimation from two example fisheries: the Atlantic weakfish (Cynoscion regalis) and the black sea bass (Centropristis striata) southern stock. Our results indicated that POE_N is the estimator with best performance among all six estimators with regard to both accuracy and precision for most of the cases. POE_N is also the robust estimator to outliers, atypical values, and autocorrelated errors. OE_N is the second best estimator. PE_N is often imprecise. Estimators with fat-tailed distribution usually result in some estimates more biased than estimators with normal distribution. The performance of POE_N and OE_N can be improved by fitting multiple indices. Our study suggested that POE_N be used for population dynamic models in future stock assessment. Multiple indices from valid surveys should be incorporated into stock assessment models. OE_N can be considered when multiple indices are available. / Master of Science

Disertacijoje nagrinėjamos papildomos informacijos panaudojimo galimybės konstruojant baigtinės populiacijos sumos, dispersijos ir kovariacijos įvertinius, bei sluoksniuojant baigtines populiacijas. Pirmiausia darbe sprendžiamas populiacijų sluoksniavimo uždavinys, kai tyrimo kintamojo skirstinys yra asimetrinis. Pasiūlomas naujas - pataisytasis geometrinis - sluoksniavimo metodas. Šis metodas modeliuojant lyginamas su trimis kitais žinomais metodais: kvadratinės šaknies iš skirstinio dažnio, geometriniu ir laipsninio sluoksniavimo metodu. Modeliavimo rezultatai rodo, kad vidutiniškai asimetrinėms populiacijoms geriausiai tinka laipsninio sluoksniavimo metodas, o ypač asimetrinėms populiacijoms geriausias yra pataisytasis geometrinis sluoksniavimas. Toliau nagrinėjami baigtinės populiacijos sumos kalibruotieji įvertiniai, sukonstruoti taikant skirtingas atstumo funkcijas. Modeliuojant tiriama šių įvertinių kokybė. Sukonstruoti nauji populiacijos kovariacijos kalibruotieji įvertiniai, naudojantys vieną, dvi ir tris svorių sistemas. Šie įvertiniai konstruojami pasirenkant skirtingas kalibravimo lygtis. Remiantis modeliais pagrįstų įvertinių teorija, čia taip pat sukonstruojamas pataisytasis tiesiniu regresiniu modeliu pagrįstas kalibruotasis populiacijos kovariacijos įvertinys. Modeliuojant įvertiniai lyginami tarpusavyje ir su standartiniais atitinkamų parametrų įvertiniais. Kalibruotieji įvertiniai yra kur kas tikslesni, jei tyrimo ir papildomų kintamųjų koreliacija yra... [toliau žr. visą tekstą] / The dissertation analyzes how to incorporate auxiliary information into the estimation of the finite population total, variance, covariance, and how to use it for the stratification of finite populations. First of all, the problem of efficient stratification in the case of skewed population is considered. A new adjusted geometric stratification method is introduced. This method is compared by simulation with the cumulative root frequency method, the geometric method, and the power method. The simulation results show that in most cases considered the power method is the most efficient one, but the adjusted geometric stratification method outperforms all the methods in the case of highly skewed populations. The calibrated estimators of finite population total, constructed using different distance functions, are considered. The quality of such estimators is analyzed by simulation. The new calibrated estimators of the finite population covariance (variance) are derived, using one or more weighting systems. Applying the model calibration theory, we construct here an adjusted linear regression model-assisted and calibrated estimator of the population covariance. The estimators derived are compared by simulation with the standard estimators of the respective parameters. The calibrated estimators of the population covariance are more efficient compared to the straight estimators provided the auxiliary variables are well correlated with the study variables. The problem of estimation... [to full text]

The dissertation analyzes how to incorporate auxiliary information into the estimation of the finite population total, variance, covariance, and how to use it for the stratification of finite populations. First of all, the problem of efficient stratification in the case of skewed population is considered. A new adjusted geometric stratification method is introduced. This method is compared by simulation with the cumulative root frequency method, the geometric method, and the power method. The simulation results show that in most cases considered the power method is the most efficient one, but the adjusted geometric stratification method outperforms all the methods in the case of highly skewed populations. The calibrated estimators of finite population total, constructed using different distance functions, are considered. The quality of such estimators is analyzed by simulation. The new calibrated estimators of the finite population covariance (variance) are derived, using one or more weighting systems. Applying the model calibration theory, we construct here an adjusted linear regression model-assisted and calibrated estimator of the population covariance. The estimators derived are compared by simulation with the standard estimators of the respective parameters. The calibrated estimators of the population covariance are more efficient compared to the straight estimators provided the auxiliary variables are well correlated with the study variables. The problem of estimation... [to full text] / Disertacijoje nagrinėjamos papildomos informacijos panaudojimo galimybės konstruojant baigtinės populiacijos sumos, dispersijos ir kovariacijos įvertinius, bei sluoksniuojant baigtines populiacijas. Pirmiausia darbe sprendžiamas populiacijų sluoksniavimo uždavinys, kai tyrimo kintamojo skirstinys yra asimetrinis. Pasiūlomas naujas - pataisytasis geometrinis - sluoksniavimo metodas. Šis metodas modeliuojant lyginamas su trimis kitais žinomais metodais: kvadratinės šaknies iš skirstinio dažnio, geometriniu ir laipsninio sluoksniavimo metodu. Modeliavimo rezultatai rodo, kad vidutiniškai asimetrinėms populiacijoms geriausiai tinka laipsninio sluoksniavimo metodas, o ypač asimetrinėms populiacijoms geriausias yra pataisytasis geometrinis sluoksniavimas. Toliau nagrinėjami baigtinės populiacijos sumos kalibruotieji įvertiniai, sukonstruoti taikant skirtingas atstumo funkcijas. Modeliuojant tiriama šių įvertinių kokybė. Sukonstruoti nauji populiacijos kovariacijos kalibruotieji įvertiniai, naudojantys vieną, dvi ir tris svorių sistemas. Šie įvertiniai konstruojami pasirenkant skirtingas kalibravimo lygtis. Remiantis modeliais pagrįstų įvertinių teorija, čia taip pat sukonstruojamas pataisytasis tiesiniu regresiniu modeliu pagrįstas kalibruotasis populiacijos kovariacijos įvertinys. Modeliuojant įvertiniai lyginami tarpusavyje ir su standartiniais atitinkamų parametrų įvertiniais. Kalibruotieji įvertiniai yra kur kas tikslesni, jei tyrimo ir papildomų kintamųjų koreliacija yra... [toliau žr. visą tekstą]

L'objectif de cette thèse est d'étudier le comportement local d'une mesure de probabilité, notamment à l'aide d'un indice de régularité locale. Dans la première partie, nous établissons la normalité asymptotique de l'estimateur des kn plus proches voisins de la densité. Dans la deuxième, nous définissons un estimateur du mode sous des hypothèses affaiblies. Nous montrons que l'indice de régularité intervient dans ces deux problèmes. Enfin, nous construisons dans une troisième partie différents estimateurs pour l'indice de régularité à partir d'estimateurs de la fonction de répartition, dont nous réalisons une revue bibliographique. / The goal of this thesis is to study the local behavior of a probability measure, using a local regularity index. In the first part, we establish the asymptotic normality of the nearest neighbor density estimate. In the second, we define a mode estimator under weakened hypothesis. We show that the regularity index interferes in this two problems. Finally, we construct in a third part various estimators of the regularity index from estimators of the distribution function, which we achieve a review.

The dissertation analyzes how to incorporate auxiliary information into the estimation of the finite population total, distribution function and quantile in the case of sample rotation. First of all estimation of the finite population total in the case of sample rotation are considered. We focus on construction of the total estimator for rotated sampling design. Successive sampling procedure using multi-phase sampling design have been developed. The composite ratio type estimator of the total using auxiliary information and its approximate variance is constructed. A simulation study, based on the real population data, is performed and the proposed estimators are compared by a traditional estima-tor for a total. The composite estimators of finite population distribution function, constructed under sampling on two occasions, are considered. Composite regression and ratio type estimators are constructed, using values of the study variable as auxiliary information obtained on the first occasion. The optimal estimators, in the sense of minimal variance, is also obtained. A simulation study, based on the real population data, is performed and the proposed estimators are compared by a traditional estimator for a distribution function. Several quantile estimators by deriving the distribution function estimators with the use of auxiliary information are proposed. Some procedures that may be used to obtain estimates of confidence intervals for quantiles in a finite population (most of... [to full text] / Disertacijoje sudaromi baigtinės populiacijos tyrimo kintamojo sumos, pasiskirstymo funkcijos, kvantilio įvertiniai esant imties rotacijai. Pirmiausia darbe nagrinėjamas baigtinės populiacijos tyrimo kintamojo sumos vertinimas esant imties rotacijai. Sudarytas sudėtinis santykinis sumos įvertinys naudojantis papildomą informaciją žinomą iš ankstesnių imties rinkimų. Modeliavimo rezultatai rodo, kad papildomos informacijos panaudojimas iš jau išrinktos imties gali pagerinti įvertinių tikslumą. Kelių ėmimų schema gali būti taikoma siekiant pagerinti baigtinės populiacijos nepaslinktojo imties planu pagristo sumos įvertinio tikslumą. Taip pat nagrinėjami baigtinės populiacijos tyrimo kintamojo pasiskirstymo funkcijos įvertiniai esant imties rotacijai. Sudaryti keli tyrimo kintamojo baigtinėje populiacijoje pasiskirstymo funkcijos sudėtiniai įvertiniai (regresinis ir santykinis) naudojant dviejų ėmimų schemą. Pasiūlyti optimalūs sudėtiniai pasiskirstymo funkcijos įvertiniai su mažiausia dispersija. Įvertiniai lyginami tarpusavyje atliekant modeliavimą su realiais duomenimis. Baigtinės populiacijos kvantilio ivertiniai sudaromi imant sudėtiniu pasiskirstymo funkcijų įvertinių atvirkštinių funkcijų įvertinius. Taip pat sudaromi pasikliautinojo intervalo įvertiniai kvantiliams, taikant kartotinių imčių metodus. Modeliuojant duomenis lyginamas jų tikslumas, daromos išvados apie pasikliautinojo intervalo įvertinių, sudarytų skirtingais būdais, kvantiliui efektyvumą.

Computed tomography is a very useful technic which allow non-invasive diagnosis in many applications for example is used with success in industry and medicine. However, manual analysis of the interesting structures can be tedious and extremely time consuming, or even impossible due its complexity. Therefore in this thesis we study and develop discrete geometry and topology algorithms suitable for use in many practical applications, especially, in the problem of automatic quantitative analysis of the human airway trees based on computed tomography images. In the first part, we define basic notions used in discrete topology and geometry then we showed that several class of discrete methods like skeletonisation algorithms, medial axes, tunnels closing algorithms and tangent estimators, are widely used in several different practical application. The second part consist of a proposition and theory of a new methods for solving particular problems. We introduced two new medial axis filtering method. The hierarchical scale medial axis which is based on previously proposed scale axis transform, however, is free of drawbacks introduced in the previously proposed method and the discrete adaptive medial axis where the filtering parameter is dynamically adapted to the local size of the object. In this part we also introduced an efficient and parameter less new tangent estimators along three-dimensional discrete curves, called 3D maximal segment tangent direction. Finally, we showed that discrete geometry and topology algorithms can be useful in the problem of quantitative analysis of the human airway trees based on computed tomography images. According to proposed in the literature design of such system we applied discrete topology and geometry algorithms to solve particular problems at each step of the quantitative analysis process. First, we propose a robust method for segmenting airway tree from CT datasets. The method is based on the tunnel closing algorithm and is used as a tool to repair, damaged by acquisition errors, CT images. We also proposed an algorithm for creation of an artificial model of the bronchial tree and we used such model to validate algorithms presented in this work. Then, we compare the quality of different algorithms using set of experiments conducted on computer phantoms and real CT dataset. We show that recently proposed methods which works in cubical complex framework, together with methods introduced in this work can overcome problems reported in the literature and can be a good basis for the further implementation of the system for automatic quantification of bronchial tree properties

Os mercados financeiros são de extrema relevância para as diversas economias do mundo. Sua efetividade na atração de capitais e investimentos é notória. Atualmente, o fluxo financeiro entre os diversos países é muito intenso, devido ao fenômeno da globalização. Tal situação provoca transmissão de crises financeiras entre diferentes países. Neste contexto, a avaliação de contágio financeiro torna-se um tema bastante relevante. A presente dissertação almejou verificar se houve contágio financeiro da crise americana de 2008 sobre os países do BRIC (Brasil, Rússia, Índia e China). Para tanto, foram utilizadas duas metodologias distintas. Uma delas, devido a Fermanian et al. (2002), foi empregada para estimação não paramétrica das cópulas via kernel. Assim, pode-se averiguar se houve aumento significativo nas medidas de dependência. A outra, desenvolvida por Remillard e Scaillet (2009), é um teste de comparação entre duas cópulas empíricas que investiga se houve mudança na estrutura de dependência no período de crise. Os dois procedimentos metodológicos indicaram a ocorrência de contágio da crise americana de 2008 sobre todos os países do BRIC. / Financial markets are extremely relevant to the world's diverse economies. Its effectiveness in attracting capital and investments is notorious. Currently, the financial flow between the various countries is very intense, due to the phenomenon of globalization. This situation leads to the transmission of financial crises between different countries. In this context, the evaluation of financial contagion becomes a very relevant issue. The present dissertation aimed to verify if there was financial contagion of the 2008 US crisis on the BRIC countries (Brazil, Russia, India and China). For that, two different methodologies were used. One of them, due to Fermanian et al. (2002), was used for non-parametric estimation of copula via kernel. Thus, it can be verified if there was a significant increase in the measures of dependence. The other, developed by Remillard and Scaillet (2009), is a test of comparison between two empirical copulas that investigates if there was a change in the dependency structure in the crisis period. The two methodological procedures indicated the occurrence of contagion of the American crisis of 2008 on all BRIC countries.

Objetivo. Comparar, teórica e empiricamente, dois estimadores do coeficiente de correlação intraclasse momento-produto de Pearson para pares repetidos Pi. O primeiro é o estimador \"natural\", obtido mediante a correlação momento-produto de Pearson para membros de uma mesma classe (rI) e o segundo, obtido como função de componentes de variância (icc). Métodos. Comparação teórica e empírica dos parâmetros e estimadores. A comparação teórica envolve duas definições do coeficiente de correlação intraclasse PI como medida de confiabilidade (*), para o caso de duas réplicas, assim como uma apresentação da técnica de análise de variância e a definição e interpretação dos estimadores ri e icc. A comparação empírica é realizada mediante um estudo de simulação Monte Carlo com a geração de pares de valores correlacionados segundo o coeficiente de correlação intraclasse, momento-produto de Pearson para pares repetidos. Os pares de valores são distribuídos segundo uma distribuição Normal bivariada, com valores do tamanho da amostra e da correlação intraclasse previamente fixados em: n= 15, 30 e 45 e pI = {O; 0,15; 0,30; 0,45; 0,60; 0,75; 0,9}. Resultados. Comparando-se o vício e o erro quadrático médio dos estimadores, bem como as amplitudes dos intervalos de confiança, tem-se como resultado que o vício de icc foi sempre menor que o vício de rI, mesmo ocorrendo com o erro quadrático médio. Conclusões. O icc é um estimador melhor, principalmente para n pequeno (por exemplo 15). Para valores maiores de n (30 ou mais), os estimadores produzem resultados iguais até a segunda casa decimal. / Objective. This thesis presents and compares, theoretically and empirically, two estimators of the intraclass correlation coefficient pI, defined as Pearson\'s pairwise intraclass correlation coefficient. The first is the \"natural\" estimator, obtained by Pearson\'s moment-product correlation for members of one class (rI) while the second was obtained as a function of components of variance (icc). Methods. Theoretical and empirical comparison of the parameters and estimators are performed. The theoretical comparison involves two definitions of the intrac1ass correlation coefficient pI as a measure of reliability (*) for two repeated measurements in the same class and the presentation of the technique of analysis of variance, as well as for the definition and interpretation of the estimators ri and icc. The empirical comparison was carried out by means of a Monte Carlo simulation study of pairs of correlated values according Pearson\'s pairwise correlation. The pairs of values follow a normal bivariate distribution, with correlation values and sample size previously fixed: n= 15, 30 e 45 and Pl = . Results. Bias and mean square error for the estimators were compared as well as the range of the intervals of confidence. The comparison shows that the bias of icc is always smaller than of rI This also applies to the mean square error. Conclusions. The icc is a better estimator, especially for n less than or equal to 15. For larger samples sízes (n 30 or more), the estimators produce results that are equal to the second decimal place. (*) Fórmula