(149d) Methods for the Adjustment of an Experimental Psd to a Reference Model and Its Verification

The Committee Draft International Standard ISO 9276-3 explains methods for the adjustment of an experimental curve to a reference model with respect to the statistical background. Furthermore the evaluation of the residual deviations after the adjustment is described principally. These evaluation principles are also valid for the comparison of experimental values to a target particle size distribution, represented only by a table of sizes and related quantitative amounts. The well known plot of experimental values in functional papers with nonlinear coordinate networks the corresponding mathematical treatment agrees with a quasi-linear regression. Here the non-linear transformation of the Y-axis results in a non-linear transformation of the Y-deviations, e.g. an other consideration of percentage deviations at the tails of a distribution than at their centre. One possibility to compensate the non-linear transformation of the Y-differences in the result of the non-linear transformation of the Y-values is the introduction of weighting factors in the quasi-linear regression. The residual variance of the experimental points to the model in the no transformed space allows the quantification of the degree of alignment and the statistical comparison of experimental distributions.