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- Gregory B Gloor, Jia Rong Wu, Vera Pawlowsky-Glahn, Juan José Egozcue
- Annals of epidemiology
- 2016

PURPOSE
The ability to properly analyze and interpret large microbiome data sets has lagged behind our ability to acquire such data sets from environmental or clinical samples. Sequencing instruments impose a structure on these data: the natural sample space of a 16S rRNA gene sequencing data set is a simplex, which is a part of real space that is… (More)

- David Lovell, Vera Pawlowsky-Glahn, Juan José Egozcue, Samuel Marguerat, Jürg Bähler
- PLoS Computational Biology
- 2015

In the life sciences, many measurement methods yield only the relative abundances of different components in a sample. With such relative-or compositional-data, differential expression needs careful interpretation, and correlation-a statistical workhorse for analyzing pairwise relationships-is an inappropriate measure of association. Using yeast gene… (More)

- N Otero, R Tolosana-Delgado, A Soler, V Pawlowsky-Glahn, A Canals
- Water research
- 2005

Most hydrogeological research includes some sort of statistical study, which is generally conducted on the raw measures of chemical variables, though there are several theoretical and practical studies warning against this practice. Arguments refer mainly to the positive character of this type of data, and to the fact that they carry only information about… (More)

Abstract: Within the special geometry of the simplex, the sample space of compositional data, compositional orthonormal coordinates allow the application of any multivariate statistical approach. The search for meaningful coordinates has suggested balances (between two groups of parts)—based on a sequential binary partition of a D-part composition—and a… (More)

- Russell Bonduriansky, Martin A Mallet, Devin Arbuthnott, Vera Pawlowsky-Glahn, Juan José Egozcue, Howard D Rundle
- Ecology letters
- 2015

Condition is a central concept in evolutionary ecology, but the roles of genetic and environmental quality in condition-dependent trait expression remain poorly understood. Theory suggests that condition integrates genetic, epigenetic and somatic factors, and therefore predicts alignment between the phenotypic effects of genetic and environmental quality.… (More)

Phenomena with a constrained sample space appear frequently in practice. This is the case, for example, with strictly positive data, or with compositional data, such as percentages or proportions. If the natural measure of difference is not the absolute one, simple algebraic properties show that it is more convenient to work with a geometry different from… (More)

- J. A. Martín-Fernández, C. Barceló-Vidal, V. Pawlowsky-Glahn, Lluis Santaló
- 2001

Abstract: The application of hierarchic methods of classification needs to establish in advance some or all of the following measures: difference, central tendency and dispersion, in accordance with the nature of the data. In this work, we present the requirements for these measures when the data set to classify is a compositional data set. Specific… (More)

- Santiago Thió-Henestrosa, Juan José Egozcue, Vera Pawlowsky-Glahn, L. Ó. Kovács, G. P. Kovács
- Computers & Geosciences
- 2008

- J. J. Egozcue, J. L. Dı́az-Barrero, V. Pawlowsky-Glahn
- 2008

A joint distribution of two discrete random variables with finite support can be displayed as a two way table of probabilities adding to one. Assume that this table has n rows and m columns and all probabilities are non-null. This kind of table can be seen as an element in the simplex of n · m parts. In this context, the marginals are identified as… (More)