Most internationally traded iron ore resources are derived from multiple mine sites, transported to a port facility where they are blended and possibly further processed prior to shipping._x000D_
Provided the proportion of contributions varies over a number of shipments an estimate can be made of the bias introduced by mine site sampling, analysis and materials handling systems, using zero-intercept multiple linear regression._x000D_
Further regression applied to the residuals allows the error variances for the source mines to be estimated._x000D_
Various sampling strategies are used by the industry. All have shipment-loading sampling on which payment or at least provisional payment is based. In most cases sampling prestockpile is used at mine sites to verify estimated production grades._x000D_
Train grades are estimated from mine stockpile grades and in some cases train grades are verified by port input sampling._x000D_
The methodology used is presented in this paper. Simulated data have been used and do not reflect the actual performance of any operator._x000D_
The merits of the various systems and the implementation and potential limitations of our method are discussed more fully in a companion paper (Ziegelaar and Everett, 2010).