Combining models in supervised classification: New developments

Resumo da comunicação oral apresentada em XVIII Jornadas de Classificação e Análise de Dados (JOCLAD2011), Vila Real, de 7 a 9 de Abril de 2011In Discrete Discriminant Analysis dimensionality problems often occur. In this context, we propose a combining models approach, taking profit from several potential models. In the bi-class case, a single combination coefficient is considered and estimated using several strategies. In the multi-class case, the decomposition into several bi-class problems embedded in a binary tree is implemented. New developments of this approach are presented and their performances assessed on real or simulated data

Features selection in Discrete Discriminant Analysis

Resumo de comunicação em póster apresentada em 14th International Conference on Applied Stochastic Models and Data Analysis (ASMDA2011), Rome, June 7-10 2011In discrete discriminant analysis dimensionality problems occur, particularly when dealing with data from the social sciences, humanities and health. In these domains, one often has to classify entities with a high number of explanatory variables when compared to the number of observations available. In the present work we address the problem of features selection in classification, aiming to identify the variables that most discriminate between the a priori defined classes, reducing the number of parameters to estimate, turning the results easier to interpret and reducing the runtime of the methods used. We specially address classification using a recently methodological approach based on a linear combination of the First-order Independence Model (FOIM) and the Dependence Trees Model (DTM). Data of small and moderate size are considered

Classification and combining models

Trabalho apresentado em SMTDA 2010: Stochastic Modeling Techniques and Data Analysis International Conference, Chania, Crete, Greece, 8-11 june 2010In the context of Discrete Discriminant Analysis (DDA) the idea of combining models is present in a growing number of papers aiming to obtain more robust and more stable models. This seems to be a promising approach since it is known that different DDA models perform differently on different subjects. Furthermore, the idea of combining models is particularly relevant when the groups are not well separeted, which often occurs in practice. Recently, we proposed a new DDA approach which is based on a linear combination of the First-order Independence Model (FOIM) and the Dependence Trees Model (DTM). In the present work we apply this new approach to classify consumers of a Portuguese cultural institution. We specifically focus on the performance of alternative models' combinations assessing the error rate and the Huberty index in a test sample. We use the R software for the algorithms' implementation and evaluation

Combining models in discrete discriminant analysis in the multiclass case

Resumo de comunicação oral em póster apresentado em COMPSTAT2008 - 18th International Conference on Computational Statistics, Porto, Portugal, 24 a 29 de Agosto 2008The idea of combining models in Discrete Discriminant Analysis (DDA) is present in a growing number of papers which aim to obtain more robust and more stable models than any of the competing ones. This seems to be a promising approach since it is known that different DDA models perform differently on different subjects (Brito et al.(2006)). In particular, this will be a more relevant issue if the groups are not well separated, which often occurs in practice. In the present work a new methodological approach is suggested which is based on DDA models' combination. The multiclass problem is decomposed into several dichotomous problems that are nested in a hierarchical binary tree (Sousa Ferreira (2000), Brito et al. (2006)) and at each level of the binary tree a new combining model is proposed to derive the decision rule. This combining model is based on two well known models in the literature - the First-order Independence Model (FOIM) and the Dependence Trees Model (DTM) (Celeux and Nakache (1994)). The MATLAB software is used for the algorithms' implementation and the proposed approach is illustrated in a DDA application

Combining Models in Discrete Discriminant Analysis

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Combining models in discrete discriminant analysis

Resumo da comunicação em póster apresentada em International Conference on Trends and Perspectives in Linear Statistical Inference (LinStat'2010), Tomar, Portugal, 27-31 July, 2010Diverse Discrete Discriminant Analysis (DDA) models perform differently on different sample observations (Brito et al. (2006)). This fact has encouraged research in combined models for DDA. This research seems to be specially promising when the a priori classes are not well separated or when small or moderate sized samples are considered, which often occurs in practice. In this work we evaluate the performance of a linear combination of two DDA models (Marques et al. (2008)): the First-Order Independence Model (FOIM) and the Dependence Trees Model (DTM) (Celeux and Nakache (1994). The pro- posed methodology also uses a Hierarchical Coupling Model (HIERM) when addressing multiclass classification problems, decomposing the multiclass problems into several bi-class problems, using a binary tree structure (Sousa Ferreira (2000)). The analysis is based both on simulated and real datasets. Results include measures of precision regarding a training set, a test set and cross-validation. The R software is used for the algorithm's implementation

Raising inclusion through na online community

The inclusion of children with deafness may be enhanced by the use of social web tools. In this scenario, building collaborative relationships among the school community as a whole is a very important process, being crucial to better understand the role of families in potentiating learning in the different contexts beyond school.info:eu-repo/semantics/publishedVersio

Design de moldes para posturas de dança. Esculturas com movimento

Tese de Mestrado em Design de ModaEsta investigação consiste num estudo do corpo do bailarino, das posturas de trabalho que este possa adoptar e da reprodução destas em peças de roupa que o obriguem a adoptar as mesmas posturas quando as veste. Abordamos ainda o estudo anatómico do corpo, a evolução do corpo dançante e a relação entre o corpo e roupa, fazendo o paralelismo entre a peça de roupa e a escultura. Apropriámo-nos do corpo da bailarina Cinira Macedo como caso de estudo, pedindo-lhe para o experimentar relativamente às articulações e segmentações do mesmo, resultando esta experimentação na selecção de duas posições, diferentes daquela que conhecemos como anatómica, estas foram analisadas a nível anatómico e seguidamente reproduzidas através da modelagem convencional aliada a metodologias de adaptação da peça de roupa à postura de trabalho. A partir os resultados finais respondemos à questão: Será que a roupa feita a partir de um molde projectado para uma determinada postura de trabalho obriga o corpo a adoptar automaticamente essa postura no momento em que a veste? As peças que resultaram desta investigação reproduziram as posições analisadas não só em termos miméticos – se nos apropriarmos das mesmas como objectos escultóricos – mas também ao nível mecânico, obrigando o corpo a reproduzir as posições em questão aquando do fechamento da peça sobre o mesmo.This research consists in the study of the dancer’s body, the working postures that the dancer can adopt, and also in their reproduction in clothing forcing the dressed body to assume the same postures. We consider the anatomic study of the body, the evolution of the body of the dancer as an instrument, as well as the relation between body and clothing by making a parallel between clothing and sculpture. We took the body of the dancer Cinira Macedo as a case study and asked her to experience it in terms of its articulations and segments, which resulted in our selection of two body positions that are different from the one we know as anatomic. The chosen positions were analyzed regarding their anatomical structure and were then reproduced in drawings made according to conventional pattern design and to techniques devised for the adjustment of clothing patterns to a working posture. The final results allowed us to answer the following research question: Does clothing made from a pattern designed for a specific working position force the body to automatically adopt the same position the moment the body puts the garment on? The results were able to reproduce the studied positions not only presenting a similar figure – if we consider the results as sculptural pieces – but also in a mechanic level, imposing the body to reproduce the same positions when it puts on the garments

Análise de acidentes de trabalho : serviços de manutenção : estudo de caso

Tese de mestrado. Engenharia de Segurança e Higiene Ocupacionais. Faculdade de Engenharia. Universidade do Porto. 200