Este trabalho generaliza a partição da distribuição de Bernoulli multivariada em distribuições de Bernoulli e como esta partição leva a um modelo de regressão e a um classificador para dados politômicos. Como ponto de partida, desejamos explicitar a função de ligação para os modelos de regressão multinomial e escrevê-la a partir de funções de distribuição, como feito no caso binomial, a fim de flexibilizá-la para além da logito usual. Para isso, estudamos as fatorações da Bernoulli multivariada em Bernoullis, bem como a multinomial em binomiais, a fim de explicitar como as funções de distribuição podem desempenhar um papel na ligação entre o espaço das covariáveis e o vetor de probabilidades. Basu & Pereira (1982) exploram tais fatorações em um problema de não resposta e Pereira & Stern (2008) as generalizam para uma classe de fatorações. Este trabalho propõe uma simplificação tanto da regressão multinomial - agregando a flexibilidade do caso binomial -, quanto da classificação politômica, no sentido de decompor o problema politômico em dicotômicos através da generalização da classe de fatorações. Um problema computacional surge pois tal classe pode ter um número muito grande de elementos distintos de acordo com o número de categorias e, assim, duas propostas são feitas para buscar uma que minimiza os riscos de classificação binomial envolvidos, passo-a-passo. A motivação para este trabalho é apresentada a fim de se estudar as performances de tais modelos de regressão e classificadores. Partimos de um problema da área médica, mais especificamente em transtorno obsessivo-compulsivo, em que desejamos classificar um indivíduo a fim de obter um fenótipo mais puro de tal transtorno e de modelá-lo a fim de buscar as covariáveis que estão relacionadas com tal fenótipo, a partir de um conjunto de dados reais. / This work explores a partition of the multivariate Bernoulli distribution in Bernoulli distributions and how this partition leads to a regression model and to a classifier for polytomous data. As starting point, we want to make explicit the link function for multinomial regression models and write it from distribution functions, as in the binomial case, in order to flexibilize it beyond the usual logit. For that, we study the factorizations of the multivariate Bernoulli in Bernoullis, as well as the multinomial in binomials, in order to make explicit as the distribution functions may play a role in the linkage between the space of covariates and the vector of probabilities. Basu and Pereira (1982) explore these factorizations in a nonresponse problem and Pereira and Stern (2008) generalize them to a class of factorizations. Thus, this work proposes a simplification of the multinomial regression - adding the flexibility from the binomial case -, and of the polytomous classification, decomposing de polytomous problem in dichotomous through the generalization of the class of factorizations. At this point, a computational problem arises because the amount of factorizations may be very large according to the number of categories and then we propose two approaches to seek a factorization that minimize the involved binomial classification risks, step-by-step. The motivation for this work is presented in order to study the performance of such regression models and classifiers. We start from a medical problem, more precisely in obsessive-compulsive disorder, in which we want to classify a patient in order to get a more pure phenotype of such disorder and model it in order to seek the related covariates, from a real dataset.

Neste trabalho, apresentamos algumas metodologias para analisar dados que possuem variável resposta categórica ordinal. Descrevemos os principais Modelos de Regressão conhecidos atualmente que consideram a ordenação das categorias de resposta, entre eles: Modelos Cumulativos e Modelos Sequenciais. Discutimos também o problema de discriminação e classificação de elementos em grupos ordinais, comentando sobre os preditores mais comuns para dados desse tipo. Apresentamos ainda a técnica de Análise Discriminante Ótima e sua versão aprimorada, baseada na utilização de métodos bootstrap. Por fim, aplicamos algumas das técnicas descritas a dados reais da área financeira, com o intuito de classificar possíveis clientes, no momento da aquisição de um cartão de crédito, como futuros bons, médios ou maus pagadores. Para essa aplicação, discutimos as vantagens e desvantagens dos modelos utilizados em termos de qualidade da classificação. / In this work, some methods to analyse data with ordinal categorical response are presented. We describe the most important and widely used Regression Models which consider the ordering of response categories like: Cumulative Models and Sequential Models. We also discuss the problem of how to discriminate and classify elements in ordinal groups, commenting on the most common predictors to this kind of data. Also we present the technique known as optimal discriminant analysis and its improved version, based on the use of bootstrap methods. Finally, we apply some of the described techniques to real financial data, intending to classify possible consumers, on acquistion of a credit card, as high, medium and low risk customers. With this application, we discuss the advantages and disadvantages of the models used in terms of quality of classification.

No description available.

Given the rise in the application of neural networks to all sorts of interesting problems, it seems natural to apply them to statistical tests. This senior thesis studies whether neural networks built to classify discrete circular probability distributions can outperform a class of well-known statistical tests for uniformity for discrete circular data that includes the Rayleigh Test1, the Watson Test2, and the Ajne Test3. Each neural network used is relatively small with no more than 3 layers: an input layer taking in discrete data sets on a circle, a hidden layer, and an output layer outputting probability values between 0 and 1, with 0 mapping to uniform and 1 mapping to nonuniform. In evaluating performances, I compare the accuracy, type I error, and type II error of this class of statistical tests and of the neural networks built to compete with them. 1 Jammalamadaka, S. Rao(1-UCSB-PB); SenGupta, A.(6-ISI-ASU)Topics in circular statistics. (English summary) With 1 IBM-PC floppy disk (3.5 inch; HD). Series on Multivariate Analysis, 5. World Scientific Publishing Co., Inc., River Edge, NJ, 2001. xii+322 pp. ISBN: 981-02-3778-2 2 Watson, G. S.Goodness-of-fit tests on a circle. II. Biometrika 49 1962 57–63. 3 Ajne, B.A simple test for uniformity of a circular distribution. Biometrika 55 1968 343–354.

<p>Human reproductive cloning came to the public´s attention when Dolly the sheep was cloned in Scotland in 1997. This news quickly spread around the world causing both excitements at the possibilities of what cloning techniques could offer, as well as apprehension about the ethical, social and legal implications should human reproductive cloning become possible. Many international organisations and governments were concerned about the impact of human reproductive cloning on human health, dignity and human rights. To this day, many institutions have drafted resolutions, protocols and position statements outlining their concerns. This paper outlines some of the major ethical issues surrounding human reproductive cloning and the position towards this novel technique taken by three important international organisations - Council of Europe, World Health Organization, and United Nations Education, Scientific and Cultural Organization - expressed in different regulatory frameworks. Proponents of human cloning occasionally point out that cloned humans are already among us in the form of twins - people with identical sets of DNA - so what is the problem? Besides avoiding the fact that natural twins are always siblings, whereas a clone could be the twin of a parent or grandparent, this observation ignores a crucial moral difference: natural twins arrive as rare creations, not as specifically designed products. Instead of being an uncontrolled, self-regulated evolutionary process, creation of man through reproductive cloning are shifting from being natural to a state of instrumentality where parental interests constitutes what is important. This shift will inevitably lead to the child being a means for some other end (parental interests). However, this is not the same as being subdued into genetic determinism, but the point brought forward is the child´s lack of freedom caused by the interests of the parents. In this sense the clone´s genome constitutes a heavy backpack because of our pre-knowledge of its physical building blocks - or in other words its potentiality. Even though the argument of genetic determinism is a weak one, our subconscious"forces"us to create hopes upon the child because of its potentiality. No longer is the evolution the creator with the dices of randomness. A new gambler is in town and this time the dices are equilateral.</p>

<p>In drug development clinical trials are designed to investigate whether a new treatment is safe and has the desired effect on the disease in the target patient population. Categorical endpoints, for example different ranking scales or grading of adverse events, are commonly used to measure effects in the trials. </p><p>Pharmacokinetic/Pharmacodynamic (PK/PD) models are used to describe the plasma concentration of a drug over time and its relationship to the effect studied. The models are utilized both in drug development and in discussions with drug regulating authorities. Methods for incorporation of ordered categorical data in PK/PD models were studied using a non-linear mixed effects modelling approach as implemented in the software NONMEM. The traditionally used proportional odds model was used for analysis of a 6-grade sedation scale in acute stroke patients and for analysis of a T-cell receptor expression in patients with Multiple Sclerosis, where the results also were compared with an analysis of the data on a continuous scale. Modifications of the proportional odds model were developed to enable analysis of a spontaneously reported side-effect and to analyze situations where the scale used is heterogeneous or where the drug affects the different scores in the scale in a non-proportional way. The new models were compared with the proportional odds model and were shown to give better predictive performances in the analyzed situations. </p><p>The results in this thesis show that categorical data obtained in clinical trials with different design and different categorical endpoints successfully can be incorporated in PK/PD models. The models developed can also be applied to analyses of other ordered categorical scales than those presented.</p>

Effects of drugs are in clinical trials often measured on categorical scales. These measurements are increasingly being analyzed using mixed-effects logistic regression. However, the experience with such analyzes is limited and only a few models are used. The aim of this thesis was to investigate the performance and improve the use of models and methods for mixed-effects categorical data analysis. The Laplacian method was shown to produce biased parameter estimates if (i) the data variability is large or (ii) the distribution of the responses is skewed. Two solutions are suggested; the Gaussian quadrature method and the back-step method. Two assumptions made with the proportional odds model have also been investigated. The assumption with proportional odds for all categories was shown to be unsuitable for analysis of data arising from a ranking scale of effects with several underlying causes. An alternative model, the differential odds model, was developed and shown to be an improvement, in regard to statistical significance as well as predictive performance, over the proportional odds model for such data. The appropriateness of the likelihood ratio test was investigated for an analysis where dependence between observations is ignored, i.e. performing the analysis using the proportional odds model. The type I error was found to be affected; thus assessing the actual critical value is prudent in order to verify the statistical significance level. An alternative approach is to use a Markov model, in which dependence between observations is incorporated. In the case of polychotomous data such model may involve considerable complexity and thus, a strategy for the reduction of the time-consuming model building with the Markov model and sleep data is presented. This thesis will hopefully contribute to a more confident use of models for categorical data analysis within the area of pharmacokinetic and pharmacodynamic modelling in the future.

Human reproductive cloning came to the public´s attention when Dolly the sheep was cloned in Scotland in 1997. This news quickly spread around the world causing both excitements at the possibilities of what cloning techniques could offer, as well as apprehension about the ethical, social and legal implications should human reproductive cloning become possible. Many international organisations and governments were concerned about the impact of human reproductive cloning on human health, dignity and human rights. To this day, many institutions have drafted resolutions, protocols and position statements outlining their concerns. This paper outlines some of the major ethical issues surrounding human reproductive cloning and the position towards this novel technique taken by three important international organisations - Council of Europe, World Health Organization, and United Nations Education, Scientific and Cultural Organization - expressed in different regulatory frameworks. Proponents of human cloning occasionally point out that cloned humans are already among us in the form of twins - people with identical sets of DNA - so what is the problem? Besides avoiding the fact that natural twins are always siblings, whereas a clone could be the twin of a parent or grandparent, this observation ignores a crucial moral difference: natural twins arrive as rare creations, not as specifically designed products. Instead of being an uncontrolled, self-regulated evolutionary process, creation of man through reproductive cloning are shifting from being natural to a state of instrumentality where parental interests constitutes what is important. This shift will inevitably lead to the child being a means for some other end (parental interests). However, this is not the same as being subdued into genetic determinism, but the point brought forward is the child´s lack of freedom caused by the interests of the parents. In this sense the clone´s genome constitutes a heavy backpack because of our pre-knowledge of its physical building blocks - or in other words its potentiality. Even though the argument of genetic determinism is a weak one, our subconscious"forces"us to create hopes upon the child because of its potentiality. No longer is the evolution the creator with the dices of randomness. A new gambler is in town and this time the dices are equilateral.

An analysis of the effect of passing vehicles’ characteristics and their impact on other drivers’ velocities was investigated. Three experimental studies were proposed and likely outcomes were discussed. Experiment 1 focused on the effect of passing vehicle type (SUV, sedan or truck) on driver speed. Drivers were hypothesized as going faster when the same vehicle type as they were driving passed them versus when no vehicle or a different vehicle passed them. Experiment 2 focused on the effect of passing SUV age on driver’s speed. Evidence suggests passing older SUVs will increase the driver’s speed more than new SUVs. Experiment 3 focused on the effect of passing SUV color on speed. Drivers were hypothesized to go faster when brighter colors (red and yellow) rather than cooler colors (grey and black) were painted on the vehicle.

En la tesi s'aborda el problema de l'homogeneïtat d'estil en el Tirant lo Blanc mitjançant l'ús de l'estilometria. Les hipòtesis al voltant de l'autoria del Tirant lo Blanc van des de l'autoria única de Joanot Martorell a la intervenció d'un segon autor, be a l'última part de la novel·la o be al llarg de tota ella, passant per altres teories més heterodoxes. A la primera part de la tesi es fa un breu repàs dels problemes que aborda l'estilometria i d'algunes eines estadístiques útils a l'hora de fer un estudi quantitatiu de l'estil literari, es resumeix la qüestió de l'autoria del Tirant lo Blanc, i es descriu la base de dades que s'ha construït per la quantificació de l'estil en el Tirant. Per atacar el problema, hem començat adaptant tècniques d'anàlisi descriptiva de dades, com els gràfics de control i l'anàlisi de correspondències. Per explotar la base de dades, proposem un mètode pràctic per estimar un o més d'un punt de canvi en seqüències de normals, de binomials i de multinomials. El mètode es basa en l'ajust de models i troba els estimadors màxim versemblants del(s) punt(s) de canvi. També hem utilitzat un mètode cluster basat en l'ajust de models per a dades politòmiques, per a agrupar les files d'una taula de contingència. Vam començar l'estudi fent un estudi comparatiu de 12 maneres diferents de mesurar la riquesa i diversitat de vocabulari. Pel que fa a les unitats lexicomètriques la llargada de paraula i l'ús de paraules freqüents i lliures del context ens han sigut molt útils per a l'estimació del punt de canvi i l'atribució d'estil als capítols. L'ús de lletres, tot i ser menys útil, serveix per a reforçar l'evidència del que trobem amb les unitats abans esmentades. La llargada de frase i la de capítol no ens ha sigut útils per a determinar una frontera d'estil en el Tirant.Per tot el que hem anat trobant estem convençuts que hi ha un canvi sobtat en l'estil entre els capítols 371 i 382, que difícilment pot ser atribuïble a l'argument. També hem trobat que després del punt de canvi conviuen capítols amb els dos estils, el que probablement reforça la teoria de que un segon autor va afegir capítols sobre un original pràcticament acabat. De totes maneres, no ens pertoca a nosaltres descobrir que el canvi d'estil no pugui ser degut a altres raons. / En la tesis se aborda el problema de la homogeneidad de estilo en el Tirant lo Blanc mediante el uso de la estilometría. Las hipótesis sobre la autoría del Tirant lo Blanc van desde la autoría única de Joanot Martorell a la intervención de un segundo autor, bien en la última parte de la novela o bien a lo largo de toda ella, pasando por otras teorías más heterodoxas. En la primera parte de la tesis se hace un breve repaso de los problemas que aborda la estilometría i de algunas herramienta estadísticas útiles para el estudio cuantitativo del estilo literario, se resume la cuestión de la autoría del Tirant lo Blanc, y se describe la base de datos que s ha construido para la ciantificación del estilo en el Tirant. Para atacar el problema, hemos empezado adaptando técnicas de análisis descriptivo de datos, como los gráficos de control y el análisis de correspondencias. Para explotar la base de datos, proponemos un método práctico para estimar uno o más de un punto de cambio en secuencias de normales, de binomiales y de multinomiales. El método se basa en el ajuste de modelos y halla los estimadores máximo verosímiles del (de los) punto(s) de cambio. También hemo utilizado un método cluster basado en el ajuste de modelos para a datos politómicos, para agrupar las filas de una tabla de contingencia. Empezamos el estudio realizando un estudio comparativo de 12 formas diferentes de medir la riqueza y diversidad de vocabulario. Las unidades lexicométricas como la longitud de palabra y el uso de palabras frecuentes y libres del contexto nos han sido muy útiles para la estimación del punto de cambio y la atribución de estilo a los capítulos. El uso de letras, a pesar de ser menos útil, sirve para reforzar la evidencia de lo que hallamos con las unidades antes citadas. La longitud de frase y la de capítulo no nos han sido útiles para a determinar una frontera de estilo en el Tirant.Por todos los resultados que hemos ido obteniendo, estamos convencidos que hay un cambio repentino en el estilo entre los capítulos 371 y 382, que difícilmente puede ser atribuible al argumento. También hemos observado que después del punto de cambio conviven capítulos con los dos estilos, lo que probablemente refuerza la teoría de que un segundo autor añadió capítulos sobre un original prácticamente acabado. De todas maneras, no es nuestra misión descubrir que el cambio de estilo no pueda ser debido a otras razones. / This Ph.D. Thesis tackles the problem of the homogeneity of style in Tirant lo Blanc, using the statistical analysis of stylistic features that are measurable but rarely consciously controlled by the author. The goal is to determine whether the style in the book is homogeneous and, if it is not, to find stylistic boundaries. Tirant lo Blanc is the main work in Catalan literature, a chivalry book hailed to be 'the best book of its kind in the world' by Cervantes in Don Quixote, and is considered to be the first modern novel in Europe. There has been an intense and long lasting debate around its authorship originating from conflicting information given in its first edition; while the dedicatory letter states that Joanot Martorell takes sole responsibility for writing the book, the colophon states that the last quarter of the book was written by Martí Joan de Galba, after the death of Martorell. Neither of the two candidate authors left any text comparable to the one under study, and therefore one can not use discriminant analysis to help classify the chapters in the book by author. The majority opinion among medievalists leans towards the single-authorship hypothesis, even though there is a rather strong dissenting minority. In the first part of the thesis we summarize some useful statistical techniques for the quantitative analysis of literary style, we describe the problems that stylometry deals with and we give the state-of-the-art of the authorship attribution problem in Tirant lo Blanc. The data base built by the quantification of style is described as well. The analysis is started by the use of graphical, Statistical Process Control and Correspondence Analysis techniques. In order to obtain maximum likelihood estimates of one or more than one change points in either normal, binomial or multinomial sequences, we propose a practical method based on the fitting of Generalized Linear Models. A cluster method for the rows of a contingency table, based on the fitting of models, is proposed too. We analyze the evolution of the diversity of the vocabulary used in the book through twelve different diversity indices. Following the lead of the extensive stylometry literature, we use word length, and the use of function words to estimate the change point and the attribution of style to the 489 chapters of the book. The use of letters, in spite of being less useful, reinforces the evidences found with the units previously cited. The sentence length and the chapter length weren't useful to determine a style boundary in Tirant The statistical analysis consistently detects a change in style somewhere between chapters 371 and 382, even though a few chapters at the end have a style similar to the ones before that boundary. It is important to remark that even though the statistical analysis supports the existence of two authors, it is not up to us to exclude the possibility that the stylistic boundary found could be explained otherwise.