Resumen de Interpretation of coal compositional data on whole-coal versus ash bases through the weighted symmetric pivot coordinates method
Na Xu, Ru Wang, Mark A. Engle, Wei Zhu, Qiang Li, Zhiwei Wang
In addition to approaches based on a number of physical and chemical analyses, statistical methods have been commonly used for determining the modes of occurrence of elements in coal. The Pearson correlation coeffcient of element concentrations vs. ash yields is the simplest method that has been widely used. Concentrations of elements in coal are usually reported on two bases: whole-coal and ash bases. Coal compositional data on whole-coal basis can be converted back to ash basis. However, in many cases, the correlation between corresponding pairs of elements in coal is inconsistent when reported on whole-coal versus ash bases. Therefore, traditional statistical methods, such as correlation analysis, based on whole-coal and ash bases can sometimes lead to misleading or confusing results. Previous investigations have suggested using logratio variance or related parameters (i.e., stability) to examine these data, as they provide consistent results regardless of the sample basis. How- ever, logratio variance based approaches are unable to distinguish the inverse relationships between parts. To provide more clarity on the relationships between parts, weighted symmetric pivot coordinates are used to analyze the correlation between elements in coal on whole-coal basis and ash basis. To illustrate this approach, 106 late Paleozoic coal samples from the Datanhao and Adaohai coal mines, Daqingshan Coalfeld, northern China, are used for perfor- mance evaluation. Experimental results show that the weight symmetric pivots method is more effective than the stability method in predicting the modes of occurrence of elements in coal for these samples, providing deeper insight than logratio variance based approaches.
