Results 271 to 280 of about 24,840,318 (307)
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Compositional data analysis in epidemiology
Statistical Methods in Medical Research, 2016Compositional data analysis refers to analyzing relative information, based on ratios between the variables in a data set. Data from epidemiology are usually treated as absolute information in an analysis. We outline the differences in both approaches for univariate and multivariate statistical analyses, using illustrative data sets from Austrian ...
Mehmet C, Mert +3 more
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Food Composition Data and Food Composition Data Bases
1992Early food composition studies were carried out to identify and determine the chemical nature of the principles in foods that affect human health. These studies, which were also concerned with the mechanisms whereby chemical constituents exert their influence, provided the basis for the early development of the science of nutrition (McCollum, 1957) and
H. Greenfield, D. A. T. Southgate
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“compositions”: A unified R package to analyze compositional data
Computers & Geosciences, 2008This contribution presents a new R package, called ''compositions''. It provides tools to analyze amount or compositional data sets in four different geometries, each one associated with an R class: rplus (for amounts, or open compositions, in a real, classical geometry), aplus (for amounts in a logarithmic geometry), rcomp (for closed compositions in ...
K. Gerald van den Boogaart +1 more
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Robust Methods for Compositional Data
2010Many practical data sets in environmental sciences, official statistics and various other disciplines are in fact compositional data because only the ratios between the variables are informative. Compositional data are represented in the Aitchison geometry on the simplex, and for applying statistical methods designed for the Euclidean geometry they ...
Peter Filzmoser, Karel Hron
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A Composite Stabilizing Data Structure
2001A data structure is stabilizing if, for any arbitrary (and possibly illegitimate) initial state, any sequence of sufficiently many operations brings the data structure to a legitimate state. A data structure is available if, for any arbitrary state, the effect of any operation on the structure is consistent with the operation's response.
Ted Herman, Imran A. Pirwani
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2011
This book present the history and development of compositional data analysis along with Aitchison's log-ratio approach. It deswcribe the state of the art both in theoretical fields as well as applications in the different fields of science.
V. Pawlowsky Glahn, BUCCIANTI, ANTONELLA
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This book present the history and development of compositional data analysis along with Aitchison's log-ratio approach. It deswcribe the state of the art both in theoretical fields as well as applications in the different fields of science.
V. Pawlowsky Glahn, BUCCIANTI, ANTONELLA
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Ranking Methods for Compositional Data
Applied Statistics, 1992Summary: In the analysis of compositional data, zero components or a non-normal distribution of the log-ratios severely limits the analysis that can be done. Ranking across both cases and components, before scaling, is suggested as a possible new approach.
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Compositional generative mapping of structured data
The 2010 International Joint Conference on Neural Networks (IJCNN), 2010We introduce a compositional generative model for topographic mapping of tree-structured data. It exploits a scalable bottom-up hidden tree Markov model to achieve a recursive topographic mapping of hierarchical information. The model allows for an efficient exploitation of contextual information from shared substructures by recursive upward ...
Davide Bacciu +2 more
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Advances in Principal Balances for Compositional Data
Mathematical Geosciences, 2017Compositional data analysis requires selecting an orthonormal basis with which to work on coordinates. In most cases this selection is based on a data driven criterion. Principal component analysis provides bases that are, in general, functions of all the original parts, each with a different weight hindering their interpretation.
J. A. Martín-Fernández +3 more
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Graphics Composition of Fundus Data
American Journal of Ophthalmology, 1984I developed a simple, inexpensive method of combining and recording clinical fundus data from a variety of sources in an instant color print or color transparency format. The system is useful for sequential observation, for planning laser treatment, for reference during photocoagulation, and for follow-up in many diseases including macular degeneration.
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