PRISCILLA RAMOS CARVALHO
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Artigo IPEN-doc 25845 Validity studies among hierarchical methods of cluster analysis using cophenetic correlation coefficient2019 - CARVALHO, P.R.; MUNITA, C.S.; LAPOLLI, A.L.The literature presents many methods to produce data set clusters and the better method choice becomes hardest because the various combinations between them based on different dissimilarity measures can lead to different cluster patterns and false interpretations. Nevertheless, little effort has been expended in evaluating these methods empirically using an archeological data set. In this way, this work has the objective to develop a comparative study of the cluster analysis methods and to identify what is the most appropriate for an archeological data set. For this, 45 ceramic fragments samples data set was analyzed by instrumental neutron activation analysis (INAA). And, five hierarchical methods of cluster were used to this data set: Single linkage, Complete linkage, Average linkage, Centroid and Ward. The validation was done calculating cophenetic correlation coefficient values by a statistical program R and the comparison between them showed the average linkage method was more accurate for the 45 ceramic fragments samples data set. With this, the statistical program R showed be an tool option for other scientists to calculate their cophenetic correlation coefficient and to identify the more accurate methods for their archeological data set.Dissertação IPEN-doc 25232 Estudo comparativo dos algoritmos hierárquicos de análise de agrupamentos em resultados experimentais2018 - CARVALHO, PRISCILLA R.Objetivou-se, com este trabalho, estudar os métodos hierárquicos de análise de agrupamentos (ligação simples, ligação completa, ligação média, centróide e de Ward com base nas distâncias Euclidiana, Euclidiana ao quadrado, Manhattan e Mahalanobis), de modo a identificar qual é o mais adequado para uma base de dados arqueológicos. Utilizou-se uma base de dados fornecida pelo Grupo de Estudos Arqueométricos do IPEN CNEN/SP, na qual foram analisadas 146 amostras de fragmentos cerâmicos de três sítios arqueológicos por análise por ativação com nêutrons instrumental, sendo determinadas as frações de massa de 24 elementos químicos: As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb e Zn. Para a determinação do melhor método, foram avaliados os dendrogramas conjuntamente com o valor dos coeficientes de correlação cofenética (CCC), obtidos para cada método. O método da ligação média mostrou-se mais coerente na formação dos agrupamentos, apresentando também os maiores valores do CCC. Por último, um script com funções do programa estatístico R foi desenvolvido para calcular o CCC, com o intuito de auxiliar os pesquisadores a encontrar o método de agrupamento mais apropriado para sua base de dados.Resumo IPEN-doc 24572 Comparative study of hierarchical clustering2017 - CARVALHO, P.R.; MUNITA, C.S.; LAPOLLI, A.L.In archaeological studies several analytical techniques are used to study the chemical and mineralogical composition of many materials of archaeological origin, generating a large data set. Thus, the multivariate statistical methods become indispensable for the interpretation of the results. These multivariate techniques, unsupervised and supervised, are accompanied by modern computational programs, which provide visualization and interpretation. Several methods have been used, such as cluster analysis, discriminant analysis, principal component analysis, among others. However, the most used is cluster analysis. The purpose of cluster analysis is to group the samples based on similarity or dissimilarity. The groups are determined in order to obtain homogeneity within the groups and heterogeneity between them. The literature presents many methods for partitioning of data set, and is difficult choose which is the most suitable, since the various combinations of methods based on different measures of dissimilarity can lead to different patterns of grouping and false interpretations. Nevertheless, little effort has been expended in evaluating these methods empirically using an archaeological data set. In this way, the objective of this work is make a comparative study of the different cluster analysis methods and to identify which is the most appropriate. For this, the study was carried out using a data set of the Archaeometric Studies Group from IPEN-CNEN/SP, in which 45 samples of ceramic fragments from three archaeological sites were analyzed by instrumental neutron activation analysis (INAA) which were determinated the mass fraction of 13 elements (As, Ce, Cr, Eu, Fe, Hf, La, Na, Nd, Sc, Sm, Th, U). The methods used for this study were: single linkage, complete linkage, average linkage, centroid and Ward. The comparison was done using the cophenetic correlation coefficient and according these values the average linkage method obtained better results. A script of the statistical program R was created to obtain the cophenetic correlation coefficient. The purpose of this script is to facilitate the statistical study of researchers who do not have much familiarity with statistical programs.Therefore, the researcher can easily check which method is most appropriate for your data set.Artigo IPEN-doc 24038 Validity studies among hierarchical methods of cluster analysis using cophenetic correlation coefficient2017 - CARVALHO, PRISCILLA R.; MUNITA, CASIMIRO S.; LAPOLLI, ANDRE L.The literature presents many methods for partitioning of data base, and is difficult choose which is the most suitable, since the various combinations of methods based on different measures of dissimilarity can lead to different patterns of grouping and false interpretations. Nevertheless, little effort has been expended in evaluating these methods empirically using an archaeological data base. In this way, the objective of this work is make a comparative study of the different cluster analysis methods and identify which is the most appropriate. For this, the study was carried out using a data base of the Archaeometric Studies Group from IPEN-CNEN/SP, in which 45 samples of ceramic fragments from three archaeological sites were analyzed by instrumental neutron activation analysis (INAA) which were determinated the mass fraction of 13 elements (As, Ce, Cr, Eu, Fe, Hf, La, Na, Nd, Sc, Sm, Th, U). The methods used for this study were: single linkage, complete linkage, average linkage, centroid and Ward. The validation was done using the cophenetic correlation coefficient and comparing these values the average linkage method obtained better results. A script of the statistical program R with some functions was created to obtain the cophenetic correlation. By means of these values was possible to choose the most appropriate method to be used in the data base.Artigo IPEN-doc 23836 Avaliação de análise de agrupamentos pelo coeficiente de correlação cofenética: estudo preliminar2016 - CARVALHO, PRISCILLA R.; MUNITA, CASIMIRO S.