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Some compositional tecniques in Geochemistry

Josep-Antoni Martín-Fernández (University of Girona, Department of Computer Science, Applied Mathematics, and Statistics)


The aim for this seminar is to increase the awareness of the peculiarities of compositional data (CoDa) and help practitioners to avoid common pitfalls in the analysis of CoDa in Geochemistry.


CoDa are vectors whose components show the relative importance of some parts of a whole. Typical examples are data expressed as percentages, ppm, ppb, or the like. This type of data appears in many applications, and the interest and importance of a consistent statistical methodology for their analysis cannot be underestimated. The log-ratio approach to CoDa was introduced back in the eighties. Since then, steady progress has been made in understanding the geometry peculiar to the compositional sample space, the D-part simplex.


The seminar will provide an introduction to theoretical and practical aspects of the statistical analysis of CoDa. It will provide mathematical background and an informal discussion forum on more advanced modeling methods. The seminar will consist of theoretical concepts and examples. Examples are done with the freeware CoDaPack (http://ima.udg.edu/codapack/). Some datasets and their particular problems will be presented, analysed and discussed interactively. Visit http://www.compositionaldata.com for further information.


Josep-Antoni Martín-Fernández

Address:  University of Girona, Department of Computer Science, Applied Mathematics, and Statistics, Edifici Politècnica 4, Campus Montilivi, M. Aurèlia Campmany, 61, E-17003 Girona, Spain.

Phone-work:  +34 616917016

Email: josepantoni.martin@udg.edu


Josep-Antoni Martín-Fernández has a degree in Mathematics. He got his PhD from the Polytechnic University of Catalonia working on “Measurements of difference and non-parametric classification of Compositional Data (CoDa)”. Currently, he is titular professor at the Department of Computer Science, Applied Mathematics and Statistics of the University of Girona (UdG, Spain). His interests lie primarily in the statistical analysis of CoDa, with more than fifty publications related with the topic. He focuses his research on the topics “Cluster Analysis of Compositional Data” and “Rounded Zeros, Values Below Detection Limit, and Missing Data”. He is principal investigator of the CoDa Research Group (UdG). He has taught many CoDa courses and seminars in the past: the first-week-of-July CoDa course in Girona (since 2012); the one-day introductory courses taught at CoDa Workshops (2005, 2008 UdG; 2011 Sant Feliu Guíxols, Spain; 2013 Vorau, Austria); and the 4-day course at U.S. Geological Survey, Reston, USA. More information at http://ima.udg.edu/~jamf/.