1,720,954 research outputs found
Um novo resíduo para classes do modelo de regressão beta - linear e não linear.
No full textEm situações em que o objetivo é analisar o comportamento de uma variável em função
de outras, os modelos de regressão são muito utilizados. A classe de modelos de regressão
beta é utilizada quando se deseja fazer esse tipo de análise e a variável resposta assume
valores no intervalo p0, 1q, como é o caso de taxas e proporções. Ferrari e Cribari-Neto
(2004) propuseram o modelo de regressão beta que utiliza uma parametrização diferente
para a distribuição beta, que é indexada pela média e pelo parâmetro de precisão. Foram
desenvolvidas duas extensões para este modelo, uma destas extensões foi proposta por
Smithson e Verkulien (2006) e considera a precisão variável, neste caso a média e a
precisão são modeladas simultaneamente. Outra extensão, proposta por Simas et al.
(2010), considera que a média e/ou a precisão podem ser relacionadas a preditores não
lineares. No processo de escolha do modelo que melhor se adequa aos dados há várias
etapas envolvidas, uma delas é a análise de resíduos. Entre os objetivos desta etapa estão:
detectar a presença de pontos aberrantes, que poderão ser influentes ou não, e por isso
devem ser investigados; verificar se a distribuição proposta para a variável resposta e se a
função de ligação estão adequadas. O objetivo desta dissertação é propor e avaliar um
novo resíduo para o modelo de regressão beta e suas extensões.CapesWhen the interest lies in analyzing the behavior of a given variable as a function of
other variables regression models are widely used. The class of beta regression models is
used when the response variable assumes values in the interval p0, 1q, such as rates and
proportions. Ferrari e Cribari-Neto (2004) proposed the beta regression model that uses
a different parametrization for the beta distribution, which is indexed by the mean and
by a precision parameter. Two extensions have been developed for this model. One of
them was proposed by Smithson e Verkulien (2006). In this extension, the mean and
precision are modeled simultaneously. Another extension, proposed by Simas et al. (2010),
considers that the mean and/or the precision may be related to nonlinear predictors. There
are several steps involved in the process of choice of the model that best fits the data,
one of them being residuals analysis. Among the objectives of this stage are: to detect
the presence of atypical points, which may or may not be influential, and thus should
be investigated; to verify if the proposed distribution for the variable response and to
determine whether the link functions are appropriate. The aim of this thesis is to propose
and to evaluate a new residual which was developed for the beta regression model and its
extensions
Análise espacial e temporal da tuberculose no Estado do Rio de Janeiro entre os anos de 2001 e 2010
No full textA tuberculose é uma doença infectocontagiosa e a probabilidade de que sua infecção evolua para a doença está associada às condições de vida da população. Segundo estimativas da OMS, um terço da população mundial está infectada. Atualmente, o Brasil ocupa o décimo nono lugar entre os 22 países responsáveis por 80% do total de casos de tuberculose no mundo. O Estado do Rio de Janeiro está entre os que possuem maior número de casos e maior taxa de incidência no país, sendo o estudo de sua difusão muito útil na tomada de decisões da administração pública voltadas para a área de saúde. Este trabalho teve como objetivo verificar o comportamento da tuberculose no Estado do Rio de Janeiro durante os anos de 2001 e 2010, através de sua dinâmica espacial e temporal. Para isso, foram realizadas uma análise espacial da taxa de incidência de tuberculose dos municípios, utilizando dois estimadores pontuais (clássico e bayesiano), e uma análise de séries temporais para encontrar um modelo adequado aos dados e que fornecesse boas previsões para o número de casos novos da doença no Estado e em dois de seus municípios mais atingido
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
