Moroccan Journal of pure and applied analysis, Sep 1, 2023
Initial conditions can have a substantial impact on the behavior of iterative root-finding techni... more Initial conditions can have a substantial impact on the behavior of iterative root-finding techniques for nonlinear equations. By allowing complex starting points and complex roots, it is possible to examine the basins of attraction in the complex plane in order to compare the performance of various iterative techniques. In this paper, a one-parameter family of third-order root-finding methods is studied by varying its parameter A within -2.0 and 2.4 and applying it to a polynomial equation of high degree (degree 25). This family includes the Euler-Chebyshev's (A = 0), Halley's (A = 1) and BSC (A = 2) techniques. According to the results, the one-parameter family provides the best performance for values near A = 1, which equals to the Halley's method.
Portugal's tourism sector is on permanent expansion and contributes significantly to the Portugue... more Portugal's tourism sector is on permanent expansion and contributes significantly to the Portuguese economy. However, it has been facing the problem of business failure. The main goal of this paper is to develop an econometric and a multivariate model for forecasting business failure in the hospitality industry using logit and discriminant analysis. The present paper does not explore the causes of business failure but rather aims to propose a model that may help anticipate failure, so that decision makers can minimize the negative effects of this phenomenon. The results confirm that the models for forecasting business failure contribute positively to setting macroeconomic policies and tourism development support programs and are relevant for investors, stockholders, and decision makers.
In order to make an informed, evidence-based decision, it is vital to recognize numbers, statisti... more In order to make an informed, evidence-based decision, it is vital to recognize numbers, statistics and concepts that are apparently transparent but are not always adequately accounted for. Health professionals, patients, and others frequently misinterpret numbers, statistics and concepts in healthcare. Among the many repercussions of health literacy, appropriate decision-making and the reduction in the number of interventions and treatments stand out, resulting in an improvement in people's health and a decrease in overtreatment and health expenses. This study intends to evaluate how properly health professionals and the public, in general, comprehend and interpret some health-related numbers. To accomplish this goal, the researchers shared a questionnaire made available online in Portugal from January 2, 2019, until April 12, 2019. The final sample comprised 485 respondents; 154 physicians, 142 nurses, and 189 people from other professions. The findings suggest that there is a...
Understanding concepts like confounding and effect modification is essential to biostatistics due... more Understanding concepts like confounding and effect modification is essential to biostatistics due to their potential influence on the interpretation of statistical results. The ability to appropriately identify and comprehend the links between research variables relies on having a firm grasp of these ideas. Statistical methods, such as stratification-related procedures and logistic regression, can be used to account for potential confounding factors. This helps to determine the real link between two variables of interest by controlling for the potentially skewing effects of the confounding variables. The ability to identify subsets of the population that may be more or less receptive to an intervention necessitates an understanding of effect modification. If, for instance, one learns that regular exercise is particularly useful in warding off heart disease in younger people, one could direct preventative efforts toward them. This paper aims to highlight the existence of associations between two binary variables that may be misleading or distorted due to the existence of confounding or effect modifier variables, that must be accounted for. The Mantel-Haenszel analysis and logistic regression are two techniques addressed in this study that help to statistically adjust the association between variables. Typically, only one of these methods is used in a study. This paper contrasts and illustrates the application of both techniques. To do this, four hypothetical situations are examined in order to provide the researcher with a comparative analysis of the two procedures and how to interpret the outcomes from each. Although the data may need to be adapted for each of the analyses, the outcomes are usually the same. The results indicate that both approaches are useful as long as they are used correctly. Nevertheless, depending on the situation, one or the other may be advisable.
Zenodo (CERN European Organization for Nuclear Research), Feb 27, 2023
The purpose of this study is to evaluate the very basic numerical skills of health professionals ... more The purpose of this study is to evaluate the very basic numerical skills of health professionals and the general public, to correctly understand the health information that comes to them routinely. The importance of mathematical and statistical literacy cannot be overstated so that informed consent can take place and adequate joint decision-making between doctor and patient can happen. The goal is todecrease the number of interventions and increase the quality of the services provided, reducing healthcare spending as a result. The competences measured in this study encompasses basic but fundamental concepts related to risk, such as the comparison of risks for its correct assessment, the estimation of the reduction of unwanted effects in a group from the r eduction in the number of unwanted effects in another group of a different size (absolute risk reduction), the recognition that the bases are necessary to be able to compare absolute frequencies between two groups, and the knowledge and perception that lowering all-cause mortality provides better evidence of benefit than lowering single-cause mortality. The results indicate a need to strengthen the numerical and statistical education of the general community, specifically physicians and nurses.
O turismo é um setor em forte expansão em Portugal e com um importante contributo na economia por... more O turismo é um setor em forte expansão em Portugal e com um importante contributo na economia portuguesa. Por isso, o equilíbrio financeiro das empresas neste setor reveste-se da maior relevância, quer para os agentes económicos, quer para os decisores políticos. Apesar disso, não existem em Portugal trabalhos de investigação que analisem o fracasso empresarial no setor da hotelaria. O objetivo principal deste estudo é propor um modelo de antecipação do fracasso empresarial, especificamente desenvolvido para o setor hoteleiro português. Para esse efeito, utilizamos uma amostra de empresas do sector à qual aplicamos a análise discriminante e a técnica logit. Os resultados obtidos mostram um elevado grau de ajustamento do modelo aos dados e indicam que o modelo utilizado constitui um importante contributo na definição de políticas macroeconómicas e programas de apoio ao desenvolvimento do turismo, sendo igualmente relevantes para as decisões de investidores e credores.ABSTRACT: In hos...
Higher Education Institutions are recognized as important actors in regional development. The Por... more Higher Education Institutions are recognized as important actors in regional development. The Portuguese higher education system comprises both Universities and Polytechnic Institutes, which face an increasing pressure to demonstrate that their presence has an impact on the surrounding communities contributing to their economic development. This paper presents the estimation of the economic impact of twelve Polytechnic Institutes, located in quite diverse regions, based on a shared model so that comparisons have a collective framework of analysis. The main results obtained show that the economic impact ranged from 1.8% to 10.6% of the local GDP and that these Institutes are major local employers.
Page 1. Chapter 14 Dynamics on Spectral Solutions of Forced Burgers Equation Mário Basto, Viriato... more Page 1. Chapter 14 Dynamics on Spectral Solutions of Forced Burgers Equation Mário Basto, Viriato Semiao, and Francisco Lage Calheiros Abstract Burgers equation @u @t Cu @u @x D ı @2u @x2 Cf .x/ is one of the simplest ...
Page 1. _____ REMark - Revista Brasileira de Marketing, São Paulo, v. 10, n. 2, p 106-125, mai./a... more Page 1. _____ REMark - Revista Brasileira de Marketing, São Paulo, v. 10, n. 2, p 106-125, mai./ago. 2011. 106 REMark – Revista ...
A numerical comparison is performed between three methods of third order with the same structure,... more A numerical comparison is performed between three methods of third order with the same structure, namely BSC, Halley's and Euler-Chebyshev's methods. As the behavior of an iterative method applied to a nonlinear equation can be highly sensitive to the starting points, the numerical comparison is carried out, allowing for complex starting points and for complex roots, on the basins of attraction in the complex plane. Several examples of algebraic and transcendental equations are presented.
The aim of this paper is to construct a new efficient iterative method to solve nonlinear equatio... more The aim of this paper is to construct a new efficient iterative method to solve nonlinear equations. The new method is based on the proposals of Abbasbandy on improving the order of accuracy of Newton-Raphson method [S. Abbasbandy, Improving Newton-Raphson method for nonlinear equations by modified Adomian decomposition method, Applied Mathematics and Computation 145 (2003) 887-893] and on the proposals of Babolian and Biazar on improving the order of accuracy of AdomianÕs decomposition method [E. Babolian, J. Biazar, On the order of convergence of Adomian method, Applied Mathematics and Computation 130 (2002) 383-387]. The convergence of the new scheme is proved and at least the cubic order of convergence is established. Several examples are presented and compared to other methods, showing the accuracy and fast convergence of this new method. Also, it is shown in this paper, that the modified AdomianÕs method developed by Babolian and Biazar to solve nonlinear equations [E. Babolian, J. Biazar, Solution of nonlinear equations by modified Adomian decomposition method, Applied Mathematics and Computation 132 (2002) 167-172] should be slightly modified, due to the fact that convergence of AdomianÕs method does not ensure convergence of the modified method. An example illustrates
Journal of Computational and Applied Mathematics, 2007
The application of Adomian's decomposition method to partial differential equations, when the exa... more The application of Adomian's decomposition method to partial differential equations, when the exact solution is not reached, demands the use of truncated series. But the solution's series may have small convergence radius and the truncated series may be inaccurate in many regions. In order to enlarge the convergence domain of the truncated series, Padé approximants (PAs) to the Adomian's series solution have been tested and applied to partial and ordinary differential equations, with good results. In this paper, PAs, both in x and t directions, applied to the truncated series solution given by Adomian's decomposition technique for Burgers equation, are tested. Numerical and graphical illustrations show that this technique can improve the accuracy and enlarge the domain of convergence of the solution. It is also shown in this paper, that the application of Adomian's method to the ordinary differential equations set arising from the discretization of the spatial derivatives by finite differences, the so-called method of lines, may reduce the convergence domain of the solution's series.
Strategies to combat academic failure in higher education rely on the identification and on the k... more Strategies to combat academic failure in higher education rely on the identification and on the knowledge of the causes associated with it. To identify these causes, a questionnaire survey was implemented in a Higher School of Technologies and Engineering. Student-related aspects were those that exhibited the greatest impact on academic success/failure. Teachers and institution/curriculum exhibited an indirect impact through mediation by student-related aspects. Other variables were identified with a negative residual impact on academic success, such as: be displaced from the habitual residence, dislike to study and be a male. With a slightly more relevant impact, emerged the sleep time on the eve of the tests.
This paper assesses the validity and reliability of two instruments measuring quality of service,... more This paper assesses the validity and reliability of two instruments measuring quality of service, the SERVPERF and SERVQUAL scales, replicated in a novel cultural settings, a Portuguese energy company. To provide insights and strategies for managerial intervention, a relation between customers' satisfaction and quality of service is established. The empirical study suggests a superior convergent and predictive validity of SERVPERF scale to measure quality of service in this settings when comparing to SERVQUAL. The main differences of this study with previous ones, are that this one resorts on a confirmatory factor analysis, the validation of the instruments is performed by using the same measures suggested by their creators and extends the line of research to a novel cultural settings, a Portuguese energy company. Concerning the relationship between service quality and customers' satisfaction, all of the quality of service attributes correlate almost equally to the satisfaction ones, with a lower weight concerning tangibles.
Moroccan Journal of pure and applied analysis, Sep 1, 2023
Initial conditions can have a substantial impact on the behavior of iterative root-finding techni... more Initial conditions can have a substantial impact on the behavior of iterative root-finding techniques for nonlinear equations. By allowing complex starting points and complex roots, it is possible to examine the basins of attraction in the complex plane in order to compare the performance of various iterative techniques. In this paper, a one-parameter family of third-order root-finding methods is studied by varying its parameter A within -2.0 and 2.4 and applying it to a polynomial equation of high degree (degree 25). This family includes the Euler-Chebyshev's (A = 0), Halley's (A = 1) and BSC (A = 2) techniques. According to the results, the one-parameter family provides the best performance for values near A = 1, which equals to the Halley's method.
Portugal's tourism sector is on permanent expansion and contributes significantly to the Portugue... more Portugal's tourism sector is on permanent expansion and contributes significantly to the Portuguese economy. However, it has been facing the problem of business failure. The main goal of this paper is to develop an econometric and a multivariate model for forecasting business failure in the hospitality industry using logit and discriminant analysis. The present paper does not explore the causes of business failure but rather aims to propose a model that may help anticipate failure, so that decision makers can minimize the negative effects of this phenomenon. The results confirm that the models for forecasting business failure contribute positively to setting macroeconomic policies and tourism development support programs and are relevant for investors, stockholders, and decision makers.
In order to make an informed, evidence-based decision, it is vital to recognize numbers, statisti... more In order to make an informed, evidence-based decision, it is vital to recognize numbers, statistics and concepts that are apparently transparent but are not always adequately accounted for. Health professionals, patients, and others frequently misinterpret numbers, statistics and concepts in healthcare. Among the many repercussions of health literacy, appropriate decision-making and the reduction in the number of interventions and treatments stand out, resulting in an improvement in people's health and a decrease in overtreatment and health expenses. This study intends to evaluate how properly health professionals and the public, in general, comprehend and interpret some health-related numbers. To accomplish this goal, the researchers shared a questionnaire made available online in Portugal from January 2, 2019, until April 12, 2019. The final sample comprised 485 respondents; 154 physicians, 142 nurses, and 189 people from other professions. The findings suggest that there is a...
Understanding concepts like confounding and effect modification is essential to biostatistics due... more Understanding concepts like confounding and effect modification is essential to biostatistics due to their potential influence on the interpretation of statistical results. The ability to appropriately identify and comprehend the links between research variables relies on having a firm grasp of these ideas. Statistical methods, such as stratification-related procedures and logistic regression, can be used to account for potential confounding factors. This helps to determine the real link between two variables of interest by controlling for the potentially skewing effects of the confounding variables. The ability to identify subsets of the population that may be more or less receptive to an intervention necessitates an understanding of effect modification. If, for instance, one learns that regular exercise is particularly useful in warding off heart disease in younger people, one could direct preventative efforts toward them. This paper aims to highlight the existence of associations between two binary variables that may be misleading or distorted due to the existence of confounding or effect modifier variables, that must be accounted for. The Mantel-Haenszel analysis and logistic regression are two techniques addressed in this study that help to statistically adjust the association between variables. Typically, only one of these methods is used in a study. This paper contrasts and illustrates the application of both techniques. To do this, four hypothetical situations are examined in order to provide the researcher with a comparative analysis of the two procedures and how to interpret the outcomes from each. Although the data may need to be adapted for each of the analyses, the outcomes are usually the same. The results indicate that both approaches are useful as long as they are used correctly. Nevertheless, depending on the situation, one or the other may be advisable.
Zenodo (CERN European Organization for Nuclear Research), Feb 27, 2023
The purpose of this study is to evaluate the very basic numerical skills of health professionals ... more The purpose of this study is to evaluate the very basic numerical skills of health professionals and the general public, to correctly understand the health information that comes to them routinely. The importance of mathematical and statistical literacy cannot be overstated so that informed consent can take place and adequate joint decision-making between doctor and patient can happen. The goal is todecrease the number of interventions and increase the quality of the services provided, reducing healthcare spending as a result. The competences measured in this study encompasses basic but fundamental concepts related to risk, such as the comparison of risks for its correct assessment, the estimation of the reduction of unwanted effects in a group from the r eduction in the number of unwanted effects in another group of a different size (absolute risk reduction), the recognition that the bases are necessary to be able to compare absolute frequencies between two groups, and the knowledge and perception that lowering all-cause mortality provides better evidence of benefit than lowering single-cause mortality. The results indicate a need to strengthen the numerical and statistical education of the general community, specifically physicians and nurses.
O turismo é um setor em forte expansão em Portugal e com um importante contributo na economia por... more O turismo é um setor em forte expansão em Portugal e com um importante contributo na economia portuguesa. Por isso, o equilíbrio financeiro das empresas neste setor reveste-se da maior relevância, quer para os agentes económicos, quer para os decisores políticos. Apesar disso, não existem em Portugal trabalhos de investigação que analisem o fracasso empresarial no setor da hotelaria. O objetivo principal deste estudo é propor um modelo de antecipação do fracasso empresarial, especificamente desenvolvido para o setor hoteleiro português. Para esse efeito, utilizamos uma amostra de empresas do sector à qual aplicamos a análise discriminante e a técnica logit. Os resultados obtidos mostram um elevado grau de ajustamento do modelo aos dados e indicam que o modelo utilizado constitui um importante contributo na definição de políticas macroeconómicas e programas de apoio ao desenvolvimento do turismo, sendo igualmente relevantes para as decisões de investidores e credores.ABSTRACT: In hos...
Higher Education Institutions are recognized as important actors in regional development. The Por... more Higher Education Institutions are recognized as important actors in regional development. The Portuguese higher education system comprises both Universities and Polytechnic Institutes, which face an increasing pressure to demonstrate that their presence has an impact on the surrounding communities contributing to their economic development. This paper presents the estimation of the economic impact of twelve Polytechnic Institutes, located in quite diverse regions, based on a shared model so that comparisons have a collective framework of analysis. The main results obtained show that the economic impact ranged from 1.8% to 10.6% of the local GDP and that these Institutes are major local employers.
Page 1. Chapter 14 Dynamics on Spectral Solutions of Forced Burgers Equation Mário Basto, Viriato... more Page 1. Chapter 14 Dynamics on Spectral Solutions of Forced Burgers Equation Mário Basto, Viriato Semiao, and Francisco Lage Calheiros Abstract Burgers equation @u @t Cu @u @x D ı @2u @x2 Cf .x/ is one of the simplest ...
Page 1. _____ REMark - Revista Brasileira de Marketing, São Paulo, v. 10, n. 2, p 106-125, mai./a... more Page 1. _____ REMark - Revista Brasileira de Marketing, São Paulo, v. 10, n. 2, p 106-125, mai./ago. 2011. 106 REMark – Revista ...
A numerical comparison is performed between three methods of third order with the same structure,... more A numerical comparison is performed between three methods of third order with the same structure, namely BSC, Halley's and Euler-Chebyshev's methods. As the behavior of an iterative method applied to a nonlinear equation can be highly sensitive to the starting points, the numerical comparison is carried out, allowing for complex starting points and for complex roots, on the basins of attraction in the complex plane. Several examples of algebraic and transcendental equations are presented.
The aim of this paper is to construct a new efficient iterative method to solve nonlinear equatio... more The aim of this paper is to construct a new efficient iterative method to solve nonlinear equations. The new method is based on the proposals of Abbasbandy on improving the order of accuracy of Newton-Raphson method [S. Abbasbandy, Improving Newton-Raphson method for nonlinear equations by modified Adomian decomposition method, Applied Mathematics and Computation 145 (2003) 887-893] and on the proposals of Babolian and Biazar on improving the order of accuracy of AdomianÕs decomposition method [E. Babolian, J. Biazar, On the order of convergence of Adomian method, Applied Mathematics and Computation 130 (2002) 383-387]. The convergence of the new scheme is proved and at least the cubic order of convergence is established. Several examples are presented and compared to other methods, showing the accuracy and fast convergence of this new method. Also, it is shown in this paper, that the modified AdomianÕs method developed by Babolian and Biazar to solve nonlinear equations [E. Babolian, J. Biazar, Solution of nonlinear equations by modified Adomian decomposition method, Applied Mathematics and Computation 132 (2002) 167-172] should be slightly modified, due to the fact that convergence of AdomianÕs method does not ensure convergence of the modified method. An example illustrates
Journal of Computational and Applied Mathematics, 2007
The application of Adomian's decomposition method to partial differential equations, when the exa... more The application of Adomian's decomposition method to partial differential equations, when the exact solution is not reached, demands the use of truncated series. But the solution's series may have small convergence radius and the truncated series may be inaccurate in many regions. In order to enlarge the convergence domain of the truncated series, Padé approximants (PAs) to the Adomian's series solution have been tested and applied to partial and ordinary differential equations, with good results. In this paper, PAs, both in x and t directions, applied to the truncated series solution given by Adomian's decomposition technique for Burgers equation, are tested. Numerical and graphical illustrations show that this technique can improve the accuracy and enlarge the domain of convergence of the solution. It is also shown in this paper, that the application of Adomian's method to the ordinary differential equations set arising from the discretization of the spatial derivatives by finite differences, the so-called method of lines, may reduce the convergence domain of the solution's series.
Strategies to combat academic failure in higher education rely on the identification and on the k... more Strategies to combat academic failure in higher education rely on the identification and on the knowledge of the causes associated with it. To identify these causes, a questionnaire survey was implemented in a Higher School of Technologies and Engineering. Student-related aspects were those that exhibited the greatest impact on academic success/failure. Teachers and institution/curriculum exhibited an indirect impact through mediation by student-related aspects. Other variables were identified with a negative residual impact on academic success, such as: be displaced from the habitual residence, dislike to study and be a male. With a slightly more relevant impact, emerged the sleep time on the eve of the tests.
This paper assesses the validity and reliability of two instruments measuring quality of service,... more This paper assesses the validity and reliability of two instruments measuring quality of service, the SERVPERF and SERVQUAL scales, replicated in a novel cultural settings, a Portuguese energy company. To provide insights and strategies for managerial intervention, a relation between customers' satisfaction and quality of service is established. The empirical study suggests a superior convergent and predictive validity of SERVPERF scale to measure quality of service in this settings when comparing to SERVQUAL. The main differences of this study with previous ones, are that this one resorts on a confirmatory factor analysis, the validation of the instruments is performed by using the same measures suggested by their creators and extends the line of research to a novel cultural settings, a Portuguese energy company. Concerning the relationship between service quality and customers' satisfaction, all of the quality of service attributes correlate almost equally to the satisfaction ones, with a lower weight concerning tangibles.
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