Browsing by Issue Date, starting with "2020-11-24"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
- Application of BIBDR in health sciences using RPublication . Oliveira, Teresa; Oliveira, AmilcarThe role of Experimental Design is very well known, considering applications to a broad range of areas, such as Agriculture, Biology, Medicine, Industry, Education, Economy, Engineering and Food Consumption Sciences. Motivated by the variety of problems faced in the several areas and simultaneously taking advantage of the emerging technological developments, new theoretical results, as well as new designs and structures, have been developed by researchers and practitioners accordingly to the needs. Experimental Design got a place among the most important statistical methodologies and, mainly because of allowing to separate variation sources, since the last century it has been strongly recommended for Health Sciences studies. In this area, particular attention has been devoted to Randomized Complete Block Designs and to Balanced Incomplete Block Designs (BIBD) - which allow testing simultaneously a number of treatments bigger than the block size. Thus, after a brief review of some particular BIBD properties and of BIBDR - Balanced Incomplete Blocks with Block Repetition, an applications to Health Sciences simulated data is illustrated, by exploring R software
- Product of two normal variables: an historical reviewPublication . Seijas-Macias, J. Antonio; Oliveira, Amilcar; Oliveira, TeresaThis paper presents a study of the evolution the study of the product of two normally distributed variables. From first approaches in the middle of the 20th Century until the most recent ones from this decade. Nowadays, existence of an unique formula for the product was not proved. Partial results using di erent approaches: Bessel Functions, Numerical Integration, Pearson Type Function.
- An overview of the systemic risk measuresPublication . Basílio, Jorge; Oliveira, Amilcar; Mahmoudvand, RahimSystemic risk is a specific type of risk that refers to the risk of an complex system to be affect or even collapse due to individual action taken by the agents that compounds that complex system. The goals of this work is based on an axiomatic approach establish a critic description of the most relevant methods used in the determination of systemic risk and identify advantages and disadvantages associated to those methods.
- Statistics and big data: different perspectivesPublication . Nunes, Sandra; Oliveira, Teresa; Oliveira, AmilcarBig Data has become the new slang in the world of information collection and analysis. The researches we conduct and the data we collect continue to grow, due to rapidly expansion of technology. Disciplines such as Computer Science, Engineering, and Statistics play a key role in the analysis of big data, each with its specificity but all equally important, an opinion that is not shared by all, being the Statistic considered the weakest link. This work attempts to show that Statistics have a distinct and essential role in this new world of Big Data, showing that Statistics and Big Data denote a crucial union. We will start with a brief introduction to Big Data and the several existing definitions.
- Inference in nonorthogonal mixed modelsPublication . Ferreira, Dário; Ferreira, Sandra; Nunes, Célia; Oliveira, Teresa; Mexia, Joao
- Semi-parametric models: an application in medicinePublication . Pereira, J. A.; Pereira, A. L.; Oliveira, TeresaModeling of medical data often requires the inclusion of non-linear forms of the predictors and, the Generalized Additive Models (GAMs) can provide an excellent fit in the presence of non-linear relationships and significant noise in the predictor variables. The accurate assessment of QT interval is of paramount importance since its prolongation (LQTS) is a life threatening condition. The QT interval is affected by heart rate and gender and may be adjusted to improve the detection of patients at increased risk. Bazett's formula is the most commonly used QT correction formula, and takes into account only the heart rate assessed by the RR interval, and cut-of values of corrected QT are defined according to gender. In this work we analyzed relevance of QRS, together with gender and RR to explain QT length using GAMs. Results showed that QRS and gender are significant to non-pathological QT modelling.