The authoritative contributions gathered in this volume reflect the state of the art in
compositional data analysis (CoDa). The respective chapters cover all aspects of CoDa ranging
from mathematical theory statistical methods and techniques to its broad range of applications
in geochemistry the life sciences and other disciplines. The selected and peer-reviewed papers
were originally presented at the 6th International Workshop on Compositional Data Analysis
CoDaWork 2015 held in L'Escala (Girona) Spain. Compositional data is defined as vectors of
positive components and constant sum and more generally all those vectors representing parts
of a whole which only carry relative information. Examples of compositional data can be found
in many different fields such as geology chemistry economics medicine ecology and
sociology. As most of the classical statistical techniques are incoherent on compositions in
the 1980s John Aitchison proposed the log-ratio approach to CoDa. This became the foundation of
modern CoDa which is now based on a specific geometric structure for the simplex an
appropriate representation of the sample space of compositional data. The International
Workshops on Compositional Data Analysis offer a vital discussion forum for researchers and
practitioners concerned with the statistical treatment and modelling of compositional data or
other constrained data sets and the interpretation of models and their applications. The goal
of the workshops is to summarize and share recent developments and to identify important lines
of future research.
