Testes de hipóteses em modelos de sobrevivência com Fração de cura

Survival models deals with the modeling of time to event data. However in some situations part of the population may be no longer subject to the event. Models that take this fact into account are called cure rate models. There are few studies about hypothesis tests in cure rate models. Recently a new test statistic, the gradient statistic, has been proposed. It shares the same asymptotic properties with the classic large sample tests, the likelihood ratio, score and Wald tests. Some simulation studies have been carried out to explore the behavior of the gradient statistic in fi nite samples and compare it with the classic statistics in diff erent models. The main objective of this work is to study and compare the performance of gradient test and likelihood ratio test in cure rate models. We first describe the models and present the main asymptotic properties of the tests. We perform a simulation study based on the promotion time model with Weibull distribution to assess the performance of the tests in finite samples. An application is presented to illustrate the studied concepts

Avaliação e correções de testes de hipóteses em modelos de sobrevivência com fração de cura

Survival models deals with the modelling of time to event data. In certain situations, a share of the population can no longer be subjected to the event occurrence. In this context, the cure fraction models emerged. Among the models that incorporate a fraction of cured one of the most known is the promotion time model. In the present study we discuss hypothesis testing in the promotion time model with Weibull distribution for the failure times of susceptible individuals. Hypothesis testing in this model may be performed based on likelihood ratio, gradient, score or Wald statistics. The critical values are obtained from asymptotic approximations, which may result in size distortions in nite sample sizes. This study proposes bootstrap corrections to the aforementioned tests and Bartlett bootstrap to the likelihood ratio statistic in Weibull promotion time model. Using Monte Carlo simulations we compared the nite sample performances of the proposed corrections in contrast with the usual tests. The numerical evidence favors the proposed corrected tests. At the end of the work an empirical application is presented.

Análise de desempenho de vendas em telecomunicações utilizando técnicas de mineração de dados

Nowadays, telecommunications is one of the most dynamic and strategic areas in the world. Organizations are always seeking to find new management practices within an ever increasing competitive environment where resources are getting scarce. In this scenario, data obtained from business and corporate processes have even greater importance, although this data is not yet adequately explored. Knowledge Discovery in Databases (KDD) appears then, as an option to allow the study of complex problems in different areas of management. This work proposes both a systematization of KDD activities using concepts from different methodologies, such as CRISP-DM, SEMMA and FAYYAD approaches and a study concerning the viability of multivariate regression analysis models to explain corporative telecommunications sales using performance indicators. Thus, statistical methods were outlined to analyze the effects of such indicators on the behavior of business productivity. According to business and standard statistical analysis, equations were defined and fit to their respective determination coefficients. Tests of hypotheses were also conducted on parameters with the purpose of validating the regression models. The results show that there is a relationship between these development indicators and the amount of sales

Contribuições da pesquisa operacional para gestão da produção e operações : uma análise exploratória da literatura

This research aims to investigate the evolution presented during three decades (1980, 1990 and 2000) of using the tools of Operations Research (OR) as a suport to decision making in Production Operation Management (POM). Hypothesis tests were made to verify the proportional growth of a given area over the decades to the detriment of the areas of facility layout, capacity planning, production scheduling and inventory management. Six journals were selected and from them more than 800 articles were used for classification and analysis in the grounds of review. It also discussed possible ways for future research and comparisons are made with other papers of literature review. As a result, it was found that areas of heuristics and simulation showed a greater quantity of contributions in all POM areas of this study

Modelo matemático para otimização dos custos de um sistema híbrido eólico-solar : aplicação no bombeamento de petróleo

This work purposes the application of a methodology to optimize the implantation cost of an wind-solar hybrid system for oil pumping. The developed model is estimated the implantation cost of system through Multiple Linear Regression technique, on the basis of the previous knowledge of variables: necessary capacity of storage, total daily energy demand, wind power, module power and module number. These variables are gotten by means of sizing. The considered model not only can be applied to the oil pumping, but also for any other purposes of electric energy generation for conversion of solar, wind or solar-wind energy, that demand short powers. Parametric statistical T-student tests had been used to detect the significant difference in the average of total cost to being considered the diameter of the wind, F by Snedecor in the variance analysis to test if the coefficients of the considered model are significantly different of zero and test not-parametric statistical by Friedman, toverify if there is difference in the system cost, by being considered the photovoltaic module powers. In decision of hypothesis tests was considered a 5%-significant level. The configurations module powers showed significant differences in total cost of investment by considering an electrical motor of 3 HP. The configurations module powers showed significant differences in total cost of investment by considering an electrical motor of 5 HP only to wind speed of 4m/s and 6 m/s in wind of 3 m, 4m and 5 m of diameter. There was not significant difference in costs to diameters of winds of 3 m and 4m. The mathematical model and the computational program may be used to others applications which require electrical between 2.250 W and 3.750 W. A computational program was developed to assist the study of several configurations that optimizes the implantation cost of an wind-solar system through considered mathematical model

Desempenho e background familiar: um estudo no acesso a uma instituição de ensino técnico federal no Brasil

This paper comprises an investigation on the influence of the variable family backgrounds (father school level, mother school level and family income) over the pupil s performance in admissions examination (entrance test or PROITEC) at Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte (IFRN). From that point of view, the main goal of this research is to analyze the influence of the family background as a determiner of the pupil´s performance in the access to Technical and Professional education at IFRN. Secondary data were used from two databases (entrance test and PROITEC) adding up to 19.226 observations to the vacancies offered in the year of 2013. Aiming at achieving the proposed goal, a conceptual model composed of three hypothesis was developed. The results were presented in four stages: stage I presentation of the descriptive statistical results of the two databases; stage II separation of the campi in clusters; stage III analysis of multiple regressions; stage IV analysis of the logistics regressions. Two statistical tests were used to validate the hypothesis: T-test and Wald test. Hypothesis 1 and 2 were confirmed and H3 was refused. The results presented favorable causal connections to the family income and the father school level variables (with bigger effect for fathers with a higher education degree). The mother school level variable did not provide statistical significance for this research. Based on this result, after this work, this institution is to develop a strategic plan to assist in the success rate of students preparing diagnoses in order to diminish the effects of the variables that impacted negatively

Testes em modelos weibull na forma estendida de Marshall-Olkin

In survival analysis, the response is usually the time until the occurrence of an event of interest, called failure time. The main characteristic of survival data is the presence of censoring which is a partial observation of response. Associated with this information, some models occupy an important position by properly fit several practical situations, among which we can mention the Weibull model. Marshall-Olkin extended form distributions other a basic generalization that enables greater exibility in adjusting lifetime data. This paper presents a simulation study that compares the gradient test and the likelihood ratio test using the Marshall-Olkin extended form Weibull distribution. As a result, there is only a small advantage for the likelihood ratio test

Desempenho e background familiar: um estudo no acesso a uma instituição de ensino técnico federal no Brasil

This paper comprises an investigation on the influence of the variable family backgrounds (father school level, mother school level and family income) over the pupil s performance in admissions examination (entrance test or PROITEC) at Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte (IFRN). From that point of view, the main goal of this research is to analyze the influence of the family background as a determiner of the pupil´s performance in the access to Technical and Professional education at IFRN. Secondary data were used from two databases (entrance test and PROITEC) adding up to 19.226 observations to the vacancies offered in the year of 2013. Aiming at achieving the proposed goal, a conceptual model composed of three hypothesis was developed. The results were presented in four stages: stage I presentation of the descriptive statistical results of the two databases; stage II separation of the campi in clusters; stage III analysis of multiple regressions; stage IV analysis of the logistics regressions. Two statistical tests were used to validate the hypothesis: T-test and Wald test. Hypothesis 1 and 2 were confirmed and H3 was refused. The results presented favorable causal connections to the family income and the father school level variables (with bigger effect for fathers with a higher education degree). The mother school level variable did not provide statistical significance for this research. Based on this result, after this work, this institution is to develop a strategic plan to assist in the success rate of students preparing diagnoses in order to diminish the effects of the variables that impacted negatively

Fatores críticos de sucesso como antecedentes da aceitação de um sistema de informação em uma universidade federal

In recent decades the public sector comes under pressure in order to improve its performance. The use of Information Technology (IT) has been a tool increasingly used in reaching that goal. Thus, it has become an important issue in public organizations, particularly in institutions of higher education, determine which factors influence the acceptance and use of technology, impacting on the success of its implementation and the desired organizational results. The Technology Acceptance Model - TAM was used as the basis for this study and is based on the constructs perceived usefulness and perceived ease of use. However, when it comes to integrated management systems due to the complexity of its implementation,organizational factors were added to thus seek further explanation of the acceptance of such systems. Thus, added to the model five TAM constructs related to critical success factors in implementing ERP systems, they are: support of top management, communication, training, cooperation, and technological complexity (BUENO and SALMERON, 2008). Based on the foregoing, launches the following research problem: What factors influence the acceptance and use of SIE / module academic at the Federal University of Para, from the users' perception of teachers and technicians? The purpose of this study was to identify the influence of organizational factors, and behavioral antecedents of behavioral intention to use the SIE / module academic UFPA in the perspective of teachers and technical users. This is applied research, exploratory and descriptive, quantitative with the implementation of a survey, and data collection occurred through a structured questionnaire applied to a sample of 229 teachers and 30 technical and administrative staff. Data analysis was carried out through descriptive statistics and structural equation modeling with the technique of partial least squares (PLS). Effected primarily to assess the measurement model, which were verified reliability, convergent and discriminant validity for all indicators and constructs. Then the structural model was analyzed using the bootstrap resampling technique like. In assessing statistical significance, all hypotheses were supported. The coefficient of determination (R ²) was high or average in five of the six endogenous variables, so the model explains 47.3% of the variation in behavioral intention. It is noteworthy that among the antecedents of behavioral intention (BI) analyzed in this study, perceived usefulness is the variable that has a greater effect on behavioral intention, followed by ease of use (PEU) and attitude (AT). Among the organizational aspects (critical success factors) studied technological complexity (TC) and training (ERT) were those with greatest effect on behavioral intention to use, although these effects were lower than those produced by behavioral factors (originating from TAM). It is pointed out further that the support of senior management (TMS) showed, among all variables, the least effect on the intention to use (BI) and was followed by communications (COM) and cooperation (CO), which exert a low effect on behavioral intention (BI). Therefore, as other studies on the TAM constructs were adequate for the present research. Thus, the study contributed towards proving evidence that the Technology Acceptance Model can be applied to predict the acceptance of integrated management systems, even in public. Keywords: Technology

Projeto em Áreas Consolidadas de Patrimônio Cultural: Propostas para a Construção de uma Metodologia de Ensino

Le thème du patrimoine culturel architectural et urbain continue d avoir une place importante dans le milieu technique et scientifique. Le concept s est élargi et aujourd hui comprend différentes procédures de projets d intervention. L importance accordée au thème amène à l inclusion de la matière de techniques rétrospectives et aux contenus qui en sont liés: conservation, restauration, restructuration et reconstruction d édifices et ensembles urbains, dans les parcours des cours d architecture et d urbanisme au Brésil établies par le Ministère de l Education Nationale (MEC) dans les années quatre-vingt-dix, postérieurement incorporés dans les directrices disciplinaires nationales. Nous partons des discussions théoriques et conceptuelles du Domaine du Patrimoine Culturel, ainsi que des principales théories pédagogiques d enseignements et d apprentissage articulées au projet. Dans ce contexte les objectifs principaux de cette thèse consistent à systématiser et à analyser les principales procédures méthodologiques contribuant pour la construction de méthodes d enseignement tournée vers des activités pratiques dans ce domaine. Pour cela, la recherche a été systématisée dans une approche à deux niveaux. En ce qui concerne le premier, basé sur des données secondaires, neuf cours d architecture et urbanisme ont étés identifiés entre institutions publiques d enseignement supérieur dont huit brésiliennes et une française, considérées représentatives en ce qui concerne les pratiques d enseignement de projet et de patrimoine culturel. Trente disciplines dédiées à la matière ont été également reconnues initialement, et postérieurement, cinq disciplines qui possèdent un emploi du temps dédié à la pratique de projet ont aussi été reconnues. Dans le deuxième cas, basée sur des données primaires, ont étés analysées les méthodologies et les stratégies d enseignement de projet basées sur les définitions des matières et des autres éléments des plans de travail avec des observations, des entrevues et des questionnaires en trois ateliers. Par rapport aux résultats nous avons constaté que toutes les écoles possèdent les contenus de la matière, mais peu d entre elles privilégient la relation du projet appliqué au patrimoine culturel. Nous avons constaté que les questions des projets dans ce contexte, même s elles sont considérées complexes, ont privilégié le listage et l analyse du site. L atelier qui intègre les fondements des théories de préservation, l histoire de l architecture et urbanisme et techniques anciennes et actuelles, est mis en valeur comme un modèle cohérent avec les propositions d intégration des connaissances théoriques et pratiques du projet appliqué à la discipline. Basé sur ces constatations il est possible de démontrer quatre étapes du projet appliqué au patrimoine culturel: 1ª) les fondements généraux qui concernent les bases théoriques sur la préservation, histoire et technique rétrospective, par exemple, l appropriation de lois et normes et la sensibilisation de l élève sur les questions de patrimoine culturel; 2ª) le contacte avec la réalité qui inclut l appropriation du problème à partir de ces acteurs, de ces échelles, de cette lecture de site et l analyse de l objet d étude; 3ª) le développement de la proposition qui inclut programmes (fonctions existantes et propositions), définitions du partit (types d intervention), conception (hypothèse et discussion) et définition de proposition; 4ª) la finalisation du projet qui consiste à développer la proposition avec sa représentation graphique et sa présentation finale. Nous concluons que le projet en Domaine du Patrimoine Culturel demande une attention spéciale et doit être présent dans les cursus considérant les principes généraux nécessaires à la formation de l élève. Le binôme projet / patrimoine signifie avoir dans le cursus universitaire les contenus et questions nécessaires les connaissances, les variables et possibilités existantes dans le projet appliqué au patrimoine culturel de façon à ce que ces connaissances soient incorporées dans l exercice de projet et n apparaissent pas comme un simple contenu théorique sans articulation avec la pratique. Naturellement ces conclusions n épuisent pas la réflexion sur la question. Nous espérons que les analyses faites contribuent à définir des méthodologies d enseignements capables d êtres vérifiées et testées dans la pratique en salle de cours, et puisse collaborer avec les nouvelles recherches surtout celles qui ont pour but des nouvelles théories pédagogiques d enseignement apprentissage du projet en Domaine du Patrimoine Culturel

Análise de DFA e de agrupamento do perfil de densidade de poços de petróleo

In recent years, the DFA introduced by Peng, was established as an important tool capable of detecting long-range autocorrelation in time series with non-stationary. This technique has been successfully applied to various areas such as: Econophysics, Biophysics, Medicine, Physics and Climatology. In this study, we used the DFA technique to obtain the Hurst exponent (H) of the profile of electric density profile (RHOB) of 53 wells resulting from the Field School of Namorados. In this work we want to know if we can or not use H to spatially characterize the spatial data field. Two cases arise: In the first a set of H reflects the local geology, with wells that are geographically closer showing similar H, and then one can use H in geostatistical procedures. In the second case each well has its proper H and the information of the well are uncorrelated, the profiles show only random fluctuations in H that do not show any spatial structure. Cluster analysis is a method widely used in carrying out statistical analysis. In this work we use the non-hierarchy method of k-means. In order to verify whether a set of data generated by the k-means method shows spatial patterns, we create the parameter Ω (index of neighborhood). High Ω shows more aggregated data, low Ω indicates dispersed or data without spatial correlation. With help of this index and the method of Monte Carlo. Using Ω index we verify that random cluster data shows a distribution of Ω that is lower than actual cluster Ω. Thus we conclude that the data of H obtained in 53 wells are grouped and can be used to characterize space patterns. The analysis of curves level confirmed the results of the k-means

Metodologias estatísticas aplicadas a dados de análises químicas da água produzida em um campo maduro de petróleo

Produced water is characterized as one of the most common wastes generated during exploration and production of oil. This work aims to develop methodologies based on comparative statistical processes of hydrogeochemical analysis of production zones in order to minimize types of high-cost interventions to perform identification test fluids - TIF. For the study, 27 samples were collected from five different production zones were measured a total of 50 chemical species. After the chemical analysis was applied the statistical data, using the R Statistical Software, version 2.11.1. Statistical analysis was performed in three steps. In the first stage, the objective was to investigate the behavior of chemical species under study in each area of production through the descriptive graphical analysis. The second step was to identify a function that classify production zones from each sample, using discriminant analysis. In the training stage, the rate of correct classification function of discriminant analysis was 85.19%. The next stage of processing of the data used for Principal Component Analysis, by reducing the number of variables obtained from the linear combination of chemical species, try to improve the discriminant function obtained in the second stage and increase the discrimination power of the data, but the result was not satisfactory. In Profile Analysis curves were obtained for each production area, based on the characteristics of the chemical species present in each zone. With this study it was possible to develop a method using hydrochemistry and statistical analysis that can be used to distinguish the water produced in mature fields of oil, so that it is possible to identify the zone of production that is contributing to the excessive elevation of the water volume.

Modelagem do desempenho ambiental dos projetos de exploração e produção aplicando equações estruturais

A legislação ambiental e os principais agentes que se relacionam com a empresa se constituem em fatores exógenos que não podem ser negligenciados ao formular-se e avaliar-se a política ambiental corporativa. As influências exógenas e seus efeitos sobre a gestão ambiental e o gerenciamento de projetos de exploração e produção (E&P) e, por essa via, sobre o desempenho ambiental, foram objetos de estudo desta tese. Embora o desempenho ambiental seja um assunto relevante, a pesquisa sobre esse tema ainda é escassa. Tal carência desponta ainda mais acentuada quando se aborda o desempenho ambiental de projetos na indústria de petróleo e gás. O principal objetivo deste estudo foi avaliar a relação entre a legislação ambiental vigente, as ações de órgãos reguladores, fornecedores, empresas terceirizadas e comunidades locais e o desempenho ambiental dos projetos de E&P na indústria de petróleo e gás e, também, analisar os efeitos do sistema de gestão ambiental e o gerenciamento dos projetos sobre tal desempenho. Na fase abdutiva, foi conduzido um estudo de caso com abordagem qualitativa em uma grande empresa brasileira do setor de petróleo e gás, na fase dedutiva, foi realizada uma pesquisa survey explanatória de corte transversal com abordagem quantitativa, incluindo 113 projetos de E&P de cinco unidades executoras da empresa. Foi formulado um modelo conceitual, com cinco construtos e sete hipóteses de pesquisa, representativo dos efeitos de fatores externos sobre o desempenho ambiental dos projetos de E&P. Os dados foram tratados aplicando a Análise Fatorial Exploratória e a Modelagem de Equações Estruturais com aplicação dos softwares IBM® SPSS® Statistics 20.0 e IBM® SPSS® Amos 18.0. O modelo de equações estruturais foi reespecificado e estimado utilizando o método de Máxima Verossimilhança e o procedimento bootstrap com 2000 reamostragens, até alcançar adequados valores dos índices de ajustamento. O modelo mostrou boa aderência às evidências empíricas, representando uma teoria explicativa dos fatores que influenciam o desempenho ambiental dos projetos de E&P na empresa estudada. As estatísticas descritivas apontaram adequado desempenho dos projetos de E&P com relação aos efluentes descartados, volume de água reutilizada, redução de resíduos e práticas de reciclagem. Identificou-se que projetos de maior porte alcançam melhor desempenho ambiental em relação aos de menor tamanho. Não foram achadas diferenças significativas entre os desempenhos de projetos executados por unidades operacionais distintas. Os resultados da modelagem indicaram que nem a legislação ambiental, nem os agentes externos exercem influência significativa sobre a sistemática da gestão dos projetos de E&P. Os agentes externos atuam sobre a gestão ambiental da empresa exercitando capacidades colaborativas, obstrutivas e propositivas. A legislação ambiental é percebida como entrave ao desenvolvimento dos projetos ao longo de seu ciclo de vida, principalmente, pelas deficiências dos órgãos ambientais. Identificou-se que o sistema de gestão ambiental influencia diretamente o Programa de Desenvolvimento e Execução de Projetos de E&P, que, por sua vez, provoca efeitos diretos e indiretos sobre o desempenho ambiental. Finalmente, comprovou-se que o Sistema de Gestão Ambiental da empresa é determinante para o desempenho ambiental dos projetos de E&P, tanto pelos seus efeitos diretos, como pelos indiretos, estes últimos mediados pela sistemática de gestão dos projetos de E&P

Análise da efetividade do transplante renal na qualidade de vida dos receptores no estado do Rio Grande do Norte

This study was developed with the aim of analyzing the effectiveness of renal transplantation on quality of life of kidney recipients in the Rio Grande do Norte State. This is a descriptive study with longitudinal design, panel type with quantitative approach to data analysis. The Quality of Life (QoL) of chronic disease kidney patients before and after kidney transplantation was assessed by the WHOQOL-bref, The population consisted of patients in pre and post-renal transplantation, the sample had 63 patients older than 18 years. The study was conducted after approval by the Research Ethics Committee of the Onofre Lopes University Hospital, Federal University of Rio Grande do Norte, No. CAAE 0008.0.294.000-10. Data collection was performed at a referral center for renal transplantation in Rio Grande do Norte, from May 2010 to May 2013. Data were analyzed using descriptive statistics and presented in tables and graphs. For statistical analyzes, Microsoft Excel XP and SPSS 15.0 software were used. The tests used were simple variance (ANOVA), t-test, Mann-Whitney and Wilcoxon test to compare means, and Spearman correlations. P values <0.05 were considered significant. The demographic data showed a predominance of people between 18 and 45 years (68.2%) with a mean age of 39.9 years (SD 12.2), male (63.5%), married (58.7%), with children (51.0%). Regarding the education level was observed that 49.2% of participants had completed primary school, and most did not engage in any work activity (90.4%) during the study period. Hemodialysis was the predominant renal replacement therapy (96.8%) and the average waiting time for execution of transplantation was 1.9 years (SD 1.9). Comparison of QoL before and after transplantation showed significant differences in all areas analyzed, demonstrating that kidney transplantation had a positive impact on QoL in chronic renal patients undergoing kidney transplantation. Sociodemographic factors did not influence the quality of life in this group of patients, indicating that transplantation was the main factor to explain the improvement in quality of life. Thus, the alternative hypothesis of the study was accept, that there is a significant difference in quality of life before and after kidney transplant. It is expected that the results of this study may contribute to the development of strategies to encourage organ donation and kidney transplantation process

Avaliação de concentrações do C-Telopeptideo de Colágeno (CTX) em mulheres no climatério

Fundação de Apoio à Pesquisa do Estado do Rio Grande do Norte