Browsing by Issue Date, starting with "2015-03-10"
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- Acquisition of competencies in mathematics through gamesPublication . Ferreira, Maria Cristina; Pereira, José António; Oliveira, AmilcarThe objective of this paper is to present the fundamentals of game theory and illustrate how the theory can be applied in education of Mathematics.Literature specific applications of game theory across all levels of instructor-led education. With a game theory model, we provide a mathematical description of a social situation in which two or more individuals or players interact. We strongly suggestthat traditional teaching techniques of mathematics should be complemented with games.
- Distribution function for the ratio of two normal random variablesPublication . Oliveira, Amilcar; Seijas-Macias, J. Antonio; Oliveira, Teresa A.The distribution of the ratio of two normal random variables X and Y was studied from [1] (the density function) and [2] (the distribution function). The shape of its density function can be unimodal, bimodal, symmetric, asymmetric, following several type of distributions, like Dirac Distribution, Normal Distribution, Cauchy Distribution or Recinormal Distribution. In this paper we study a different approximation for this distribution Z = X /Y , as a function of four parameters: ratio of the means of the two normal variables, ratio of the standard deviations of the two normal variables, the variation coefficient of the normal variable Y , and the correlation between the two variables. A formula for the Distribution function and the density function of Z is given. In addition, using graphical procedures we established singularity points for the parameters where the approximation given for Z has a non normal shape.
- Linear regression on the characterization of elements of natural origin and possible implications in the use of groundPublication . Oliveira, Amilcar; Caroço, Adolfo; Batista, Maria; Oliveira, Maria Manuela; Borges, José; Oliveira, Teresa A.The observation of certain higher chemical element concentration, such as uranium and radiometric values, in the Alegrete-Assumar region of Portugal, has shown that locally occurrence of radioactive quartzites is responsible for these high values. The geostatistical treatment of exploration data and the crossing of the database with other variables, such as land use, allows one to study how these may affect the human health.
- Stochastic response surface methodology: a study in the human health areaPublication . Leal, Maria da Conceição Dias; Oliveira, Amilcar; Oliveira, Teresa A.In this paper we review Stochastic Response Surface Methodology as a tool for modeling uncertainty in the context of Risk Analysis. An application in the survival analysis in the breast cancer context is implemented with R software.