Guest Editorial: Special Issue: Compositional Data Modelling

Abstract

Compositional data refer to data where the relevant information is contained in the ratios between the values of the variables, called compositional parts. Typical examples are data consisting of chemical concentrations in some sample medium or export figures from trade of various commodity groups. In the first example, an increase of the concentration of one element necessarily leads to a decrease in other elements, because the concentration is expressed in a relative unit (e.g., mg/kg). In the second example, the raw export numbers of countries with different size and GDP are not directly comparable. For both examples, the ratios between the variables contain the meaningful information to be analyzed, which is done in compositional data analysis. This special issue on 'Compositional Data Modelling' outlines the ongoing research in some topics of compositional data analysis. It can be considered as an outcome of the Fifth International Workshop on Compositional Data Analysis (CoDaWork), which was held from 3-7 June, 2013, in Vorau, a wonderful small village in the Austrian mountains, where the Guest Editors were among the main organizers. This workshop series intends to bring together specialists in the field as well as practitioners that are confronted with this kind of data. This issue includes five articles which we have organized alphabetically according to the first author's name.