Geochemical data are typically reported as compositions, in the form of some proportions
such as weight percents, parts per million, etc., subject to a constant sum (eg 100%,
1,000,000 ppm). This latter implies that such data are “closed”; that is, for a composition of D-
components, only D− 1 components are required. The statistical analysis of compositional
data has been a major issue for more than 100 years. The problem of spurious correlation,
introduced by Karl Pearson in 1897, affects all data measuring parts of some whole, which …