Geology is among the many branches of science in which compositional data (CoDa) arise naturally. In branches such as geochemistry, compositional data seem to occur typically, when one normalizes raw data or when one obtains the output from a constrained estimation procedure, such as percentages, ppm, ppb, molar concentrations, etc.
Compositional or constrained data have proved difficult to handle statistically because of the awkward constraint that the components of each vector must sum to unity. The special property of compositional data (the fact that the determinations on each specimen sum to a constant) means that the variables involved in the study occur in constrained space defined by the simplex, a restricted part of real space.
It is important for geochemists and geologists in general to be aware of the fact that the usual multivariate statistical techniques are not applicable to compositional data. They need to have access to appropriate techniques as they emerge and become available.
Pearson was the first to point out dangers that may befall the analyst who attempts to interpret correlations between Ratios whose numerators and denominators contain common parts. More recently, Aitchison, Pawlowsky-Glahn, S. Thio, and other statisticians have developed the concept of Compositional Data Analysis, pointing out the dangers of misinterpretation of closed data when treated with “normal” statistical methods.
Learning about all elements of CoDa
A webinar from Compliance4All, a leading provider of professional trainings for all the areas of regulatory compliance, will throw light on all the important aspects of CoDa. At this session, Ricardo Valls, a professional geologist with thirty years in the mining industry, and who has extensive geological, geochemical, and mining experience, managerial skills, and a solid background in research techniques; will be the speaker.
At this session, Ricardo will present several real case studies he has developed, to demonstrate the advantages of applying various aspects of the CoDa analysis in the search for and evaluation of ore bodies by comparing them with regular statistical modelling of geochemical data.
At this webinar, which will be of high value to personnel involved in mining, such as Geologists, Geochemists, Exploration Personnel, Graduate Students, and Post-Graduate Students; Ricardo will cover the following areas:
o History of the Problem
o The Current Situation
o The Model
o Normal Statistical Processing of the Data
o Compositional Data Analysis
o Factor and Principal Component Analysis
o Dealing with zero and b.d.l. Values
Conclusions and Recommendations.
For more click the advantages of applying different aspects