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Introduction
Robert Wayne Samohyl is currently retired from the Departamento de Engenharia de Produção e Sistemas, Federal University of Santa Catarina however he continues doing research and lecturing. Robert does research in Econometrics, Macroeconomics and Quality Assurance Engineering. His current project is 'Acceptance Sampling'.
Additional affiliations
January 1994 - August 1994
August 1989 - December 1989
January 1989 - August 1989
Publications
Publications (58)
The procedure we propose uses polling data to construct a probability model that recreates numerical results from a large number of simulated elections. Probabilistic measures of candidate success have become increasingly common in some areas of election prognosis, moving away from traditional procedures based on confidence intervals. Here we show...
A utilização de objetos de aprendizagem com interfaces digitais, interativas e dinâmicas é uma alternativa que pode ser inovadora no ensino de conceitos de Estatística e na realização de suas análises, uma vez que possibilita tipos de visualização e interatividade que, em grande parte das vezes, não são alcançados no ambiente lápis e papel. Neste a...
This paper questions some aspects of attribute acceptance sampling in light of the original concepts of hypothesis testing from Neyman and Pearson (NP). Attribute acceptance sampling in industry, as developed by Dodge and Romig (DR), generally follows the international standards of ISO 2859, and similarly the Brazilian standards NBR 5425 to NBR 542...
The standards and procedures for Lot Quality Assurance Sampling (LQAS), usually based on simple random sampling (SRS) plans, can be improved by taking into account the correct usage of hypothesis testing and when necessary the application of the hypergeometric distribution instead of the binomial and Poisson approximations. For the area of public h...
This paper aims to develop and implement a method to identify the causes of the choice of a course and the reasons for evasion in higher education. This way, we sought to identify the factors that influence student choice to opt for Higher Education Institution parsed, as well as the factors influencing its evasion. The methodology employed was the...
The aim of this study is to analyze the use of a binomial cumulative sum chart (CUSUM) to monitor the presence of total coliforms, biological indicators of quality of water supplies in water treatment processes. The sample series were monthly taken from a water treatment plant and were analyzed from 2007 to 2009. The statistical treatment of the da...
O abastecimento de agua em termos de quantidade e qualidade e uma preocupacao crescente. A qualidade da agua tem sido comprometida desde o manancial, pelo lancamento de efluentes e residuos, o que exige investimento nas estacoes de tratamento para garantir a qualidade da agua fornecida. A agua que sai das estacoes de tratamento para a rede de distr...
The effective simultaneous monitoring of the many quality characteristics of a production process often depends on statistical tools that are becoming more and more specific. The goal of this paper is to investigate, via an industrial application, if there are significant differences in sensitivity between the use of Multivariate Cumulative Sum (MC...
Governmental agencies, the back office of private firms and nongovernmental organizations experience bureaucratic processes that are often repetitive and out-of-date. These imperfections cause resource misuse and support activities that diminish to the value of the process. An important element of these bureaucratic processes is checking whether ce...
The objective of this study is to statistically analyze and control an industrial process in which the Shewhart style control chart is used. Through an axiomatic quantitative research, several options of application are evaluated, such as the use of the CUSUM control chart individually or a combined Shewhart-CUSUM chart probabilistically combined....
Continual improvement in the quality of products, processes, and services has been facilitated by applying statistical methods. The statistical process control technique (SPC) provides enhanced results, as it utilizes statistical methods throughout all the developmental stages of a project and/or production. One of these techniques is control chart...
Os tradicionais graficos do tipo Shewhart sao recomendados na deteccao de grandes alteracoes namedia de um processo e, os graficos de soma cumulativa (CUSUM) na sinalizacao de pequenas emoderadas alteracoes. Todavia, se a magnitude da mudanca for desconhecida ou se modifica aolongo do tempo, nenhum dos graficos mencionados ira ter um bom desempenho...
The purpose of this study is to investigate the performance of a combined CUSUM-Shewhart chart for binomial data, when compared to individual Shewhart and CUSUM control charts for large shifts in the process mean. The comparison is performed by analyzing several ARL (Average Run Length) measures. The ARL of the combined control charts is identified...
O monitoramento e controle de epidemias permitem melhor atuação das autoridades sanitárias e a criação de políticas preventivas visando assegurar a saúde da população. A aplicação de gráficos de Controle Estatístico de Processos na saúde pública tem tido uma evolução crescente nos últimos anos. Este artigo tem por objetivo investigar e analisar a a...
In this study, pigment production by Monascus ruber in submerged fermentation using glycerol as substrate was optimized by employing factorial design and response surface techniques. The variables evaluated were the glycerol and monosodium glutamate concentrations, having as responses pigment and biomass productions. The monosodium glutamate concen...
O projeto de otimização de um gráfico de controle tem como referência o tamanho de mudança do processo que é considerado importante a ser detectado. O gráfico de controle de Soma Acumulada (CUSUM - Cumulative SUM) é uma das melhores alternativas disponíveis para detectar de forma eficiente, pequenas mudanças de um processo. Neste trabalho propõe-se...
RESUMO Para a análise de correlação entre 38 empresas de transporte e logística foi utilizado o coeficiente Spearman, analisando 46 critérios de desempenho incluindo ferramentas e boas práticas de produção (Anexo). O estudo partiu de uma revisão bibliográfica sobre a utilização do benchmarking na logística e no uso de dados categorizados para reali...
Normal 0 21 false false false MicrosoftInternetExplorer4 Normal 0 21 false false false MicrosoftInternetExplorer4 In this paper was verified the possibility of improving the monthly forecasts of the Value Added Tax on Merchandise and Services (ICMS) collected by the State of Santa Catarina, Brazil. Dynamic regression will be used based on the conce...
Gráficos de controle baseado nos resíduos de Poisson têm sido têm sido úteis para monitorar o número de não conformidade em um processo industrial. O modelo de regressão de Poisson é o mais popular dos modelos lineares generalizados, o qual é usado para modelar dados de contagem. O modelo de regressão de Poisson tem uma suposição de que a variância...
Nos métodos de previsão univariados, atualmente os modelos de suavização exponencial tem recebido muito interesse por parte dos pesquisadores e diversas melhorias estão sendo incorporadas a estes modelos. O objetivo deste artigo é apresentar um aplicativo para fazer previsões, desenvolvido no NNQ (núcleo de normalização e qualimetria) da Universida...
This paper aims to apply the zip code concept in real data of a casting industry in
Santa Catarina, in order to identify features and particularities of this process, as well
as improving useful qualities for employees who monitories the company procedure,
or even other people who work and deal with similar processes. The paper uses
basically the c...
Bob Samohyl analyzes a manufacturing company that forecasts orders without a statistical model, on the basis of executive judgment alone. He shows how the company can quickly determine how much potential there is for improving forecast accuracy using even simple statistical models, also noting that cost savings are a likely by-product. Copyright In...
Com a utilização cada vez maior do Sistema de Posicionamento Global (GPS), na determinação precisa de posições, torna-se de fundamental importância a consideração de alguns fatores que, ao serem negligenciados, podem prejudicar a qualidade dos resultados. No empíricos e testes estatísticos, a verificação da distribuição das observações, no que diz...
RESUMO: Com a utilização cada vez maior do Sistema de Posicionamento Global (GPS), na determinação precisa de posições, torna-se de fundamental importância a consideração de alguns fatores que, ao serem negligenciados, podem prejudicar a qualidade dos resultados. No processamento e ajustamento das observações GPS utilizando o método dos mínimos-qua...
The main purpose of this research is to implement a multivariate feedback adjustment proportional to the last deviation from the target, in the set of variables wandering around the target. To apply the controller equation it will be necessary to study the exponentially weighted moving average (EWMA) statistic, in order to determine the behavior of...
The main purpose of this research is to implement a multivariate feedback adjustment proportional to the last deviation in relation to the target of the variables that wandering around the target. In order to apply the controller equation it will be necessary to study the exponentially weighted moving average statistics, so that the target disturba...
Este artigo apresenta uma estratégia para identificar efeitos de locação e efeitos de dispersão em experimentos fatoriais não-replicados, fracionados ou não. A estratégia é adaptada para projetos experimentais com poucas replicações, sendo ilustrada em um exemplo prático. Além da estratégia proposta, outros métodos típicos de experimentos com repli...
The main purpose of this research is to implement a multivariate feedback adjustment proportional to the last deviation in relation to the target of the variables that wandering around the target. In order to apply the controller equation it will be necessary to study the exponentially weighted moving average statistics, so that the target disturba...
The reliability of a product is without doubt one of the most important aspects of a program of quality improvement. The main purpose of this research was to propose a multivariate methodology to determine reliability and mean time to failure the of a product, whose components have correlated life times. The methodology developed was able to reduce...
Starting in the 1970's, the Brazilian agricultural sector has experienced an important process of modernization, whose principal effects include advances in technological progress and gains in productivity. The primary objective of this paper is to analyze technological progress and total productivity growth in the Brazilian agricultural sector dur...
O artigo discute a dívida pública mobiliária federal e seus determinantes. Desde 1992, o débito cresceu cerca de 4.000%, para 45% do PIB, e continua crescendo, principalmente em função das elevadas taxas de juros. A política de esterilização da entrada de moeda estrangeira foi um importante fator de expansão até 1998, quando o regime cambial foi mo...
The behavior of the milk delivery to the industries from Santa Catarina State was analysed. The milk production in the State of Santa Catarina has been increasing in the last years, with an outstanding monthly seasonality. The use of exponential method of Holt-Winters to forecast the monthly milk deliveries was not satisfactory, because the additiv...
Variance models are highly important in developing robust products and processes. These models can be employed in process robustness studies through the use of response surface methodology. In most of the applications the models are constructed in terms of the logarithm of the sample variance or the logarithm of squared residuals. This paper presen...
It is recognized in the literature that stochastic control models whether discrete or continuous become unwieldy when equations and state variables are more than just a few. Needless to say, when the optimizing models are nonlinear, problems are compounded. This fact has made the use of stochastic control inadvisable as a tool in portfolio theory....
This paper proposes a modified version of an algorithm for nonlinear stochastic control. The application of the algorithm is with the classic cost data from Holt, Muth, Modigliani and Simon (1955, 1960). New equations are reestimated using more recent econometrics techniques without requiring linear or quadratic forms, and the algorithm is applied...
RESUMO Este artigo estuda o comportamento da base monetária e seus determinantes próximos no Brasil entre janeiro de 1992 e março de 1996. Para tanto, o artigo analisa as variações mensais da base, utilizando coeficientes de correlação e a participação relativa de cada determinante na variação total. A análise demonstra que existem várias diferença...
The maintenance of the accuracy (quality) of forecasts should be a constant worry for both forecasters and users of forecasts. Techniques for monitoring the underlying structure of forecasts should aim to diminish the high costs of inaccurate forecasts but also should diminish the need for unnecessary interventions in the forecasting process. This...
The energy crisis faced by Brazil in 2001 middle unchained a process of rationing of electric energy in the Southeastern region of the country and a called phenomenon "rationalization of consumption" in the South region. This phenomenon was responsible for the modification of habits and behaviors had, until then, as standards in that it said respec...
RESUMO: Este artigo verifica a existência de relacionamento de longo prazo entre os índices da Bolsa de Valores de São Paulo e das bolsas de valores de Santiago, Buenos Aires e Lima, durante o período de janeiro de 1990 a julho de 1998, a partir de cotações de fechamento semanais de sexta-feira. Utiliza-se neste trabalho um modelo de mecanismo de c...
Resumo O presente trabalho tem como objetivo determinar o nível de utilização das ferramentas de Tempos e Métodos nas médias e grandes empresas do Vale do Itajaí e do Norte do Estado de Santa Catarina. Isto se justifica pela inexistência de estudos anteriores sobre este tema na região. Através de questionários foi realizado um levantamento para obt...
This paper esteems a function demand of gasoline to Brazil, using techniques of cointegration and error correction model (ECM). The period to be esteems is from 1955 to 1995, the goals is the forecast of four possible scenarios. The results found suggest the good adaptation of the forecast and the coefficients of elasticity indicate that the gasoli...
The optimization of products and processes is an important issue for all companies. Concerning this theme, the construction of variability models is a key aspect for those who are searching for robust products and processes. So far, regression routines using the logarithm of the sample variance has been widely used. However, these procedures are no...
Abstract. Thesis (Ph. D.)--Rice University, 1979. Includes bibliographical references (leaves 136-139). Photocopy of typescript.
