ISO 11726:2017 describes procedures for validating alternative methods of analysis for coal and coke either directly by comparison with the relevant International Standard method or indirectly by comparison with reference materials that have been exhaustively analysed using the relevant International Standard method.
The statistical analysis methods used are parametric, i.e. their use is possible only when the characteristic is expressed as a simple number on an approximately linear scale. The results from some methods, for example the Gray-King coke type, are not so expressed and the methods given here need to be used only if the data are converted to a parametric scale.