This International Standard specifies experimental methods for checking the bias of sampling of iron ores, when sampling is carried out in accordance with the methods specified in ISO 3082, having as reference a stopped-belt sampling method. It is recommended that an inspection of the mechanical sampling system be carried out before conducting bias testing. Sampling systems not completely in accordance with ISO 3082 are not always expected to be biased. Therefore, bias checking may be done when there is some disagreement about the importance of some departure from the conditions of ISO 3082. If one party argues that the bias is likely to be substantial under some particular set of conditions then bias testing should mostly be done when those conditions apply. NOTE The method for analysis of experimental data described here may also be applied: a) for checking the bias of sample preparation of iron ores, having as reference the methods for sampling preparation according to ISO 3082; b) for checking the bias of size distribution of iron ores by sieving, having as reference the hand sieving methods according to ISO 4701; c) for checking a possibly significant difference in the results obtained from the samples of one lot collected at different places, for example, a loading point and unloading point.