Displaying similar documents to “Profile analysis of mothers susceptible to contaminant exposure in the Algarve region: Application of the HJ-BIPLOT method”

Correspondence analysis and two-way clustering.

Antonio Ciampi, Ana González Marcos, Manuel Castejón Limas (2005)

SORT

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Correspondence analysis followed by clustering of both rows and columns of a data matrix is proposed as an approach to two-way clustering. The novelty of this contribution consists of: i) proposing a simple method for the selecting of the number of axes; ii) visualizing the data matrix as is done in micro-array analysis; iii) enhancing this representation by emphasizing those variables and those individuals which are 'well represented' in the subspace of the chosen axes. The approach...

Comparison of Multivariate Analysis Methodologies in a Palliative Care Setting

Isabel Pinto Doria, Ana Sousa Ferreira, Otília Dias, Helena Bacelar-Nicolau, Georges Le Calvé (2012)

Biometrical Letters

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This study is focused on measuring the quality and the satisfaction with the palliative care provided to oncology patients in domicile. The SERVQUAL methodology adapted for the Portuguese context was used to evaluate the quality of palliative care and patient satisfaction. The Portuguese SERVQUAL questionnaire is composed of five perception scales and two questionnaires, one about the patient and another about the caregiver. The data analysis presented is the analysis of the answers...

Notes on the bias of dissimilarity indices for incomplete data sets: the case of archaelogical classification.

Angela Montanari, Stefania Mignani (1994)

Qüestiió

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The problem of missing data is particularly present in archaeological research where, because of the fragmentariness of the finds, only a part of the characteristics of the whole object can be observed. The performance of various dissimilarity indices differently weighting missing values is studied on archaeological data via a simulation. An alternative solution consisting in randomly substituting missing values with character sets is also examined. Gower's dissimilarity coefficient...

A review of canonical coordinates and an alternative to correspondence analysis using Hellinger distance.

C. Radhakrishna Rao (1995)

Qüestiió

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In this paper a general theory of canonical coordinates is developed for reduction of dimensionality in multivariate data, assessing the loss of information and plotting higher dimensional data in two or three dimensions for visual displays. The theory is applied to data in two way tables with variables in one category and samples (individual or populations) in the other. Two types of data are considered, one with continuous measurements on the variables and another with frequencies...

The post randomisation method for protecting microdata.

José Gouweleeuw, Peter Kooiman, Leon Willenborg, Peter-Paul De Wolf (1998)

Qüestiió

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This paper describes the Post Randomisation Method (PRAM) for disclosure protection of microdata. Applying PRAM means that for each record in the data file according to a specified probability mechanism the score on a number of variables is changed. Since this probability mechanism is known, the characteristics of the latent true data can unbiasedly be estimated from the observed data moments in the perturbed file. PRAM is applied to categorical variables. It is shown that...

An alternative methodology for imputing missing data in trials with genotype-by-environment interaction: some new aspects

Sergio Arciniegas-Alarcón, Marisol García-Peña, Wojtek Janusz Krzanowski, Carlos Tadeu dos Santos Dias (2014)

Biometrical Letters

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A common problem in multi-environment trials arises when some genotypeby- environment combinations are missing. In Arciniegas-Alarcón et al. (2010) we outlined a method of data imputation to estimate the missing values, the computational algorithm for which was a mixture of regression and lower-rank approximation of a matrix based on its singular value decomposition (SVD). In the present paper we provide two extensions to this methodology, by including weights chosen by cross-validation...

Distance-based regression in prediction of solar flare activity.

Anna Bartkowiak, Maria Jakimiec (1994)

Qüestiió

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Short-term prediction of solar flare activity using multiple regression methods was considered. The variables describing active regions the given day were used to predict the flare activity on the next day. Two groups of observational data covering the years 1988 and 1989 were dealt with. Some variants of the distance-based regression as proposed by Cuadras and Arenas (1990) appeared to be superior to the ordinary least squares method by describing more accurately the data sets under...