Every step on the path from the mine to the smelter invites a comparison between material inputs on one side and outputs plus accumulation on the other. Or put simply, between what you think you have produced with what you find you have at hand._x000D_
The discrepancy between these sets of comparisons is the error. Following that error in a systematic and objective manner is a way to improve the mine's measurement systems, that in turn leads to more accurate accounting for ores, metals and concentrates._x000D_
Because the control of production is so tightly coupled with the accounting of materials, any lasting improvements in materials accounting will benefit the predictions of materials movements and quality. This translates to more reliable planning and scheduling in stockpile management, logistics, shipping and marketing._x000D_
The statistical tools described are direct adaptations from the long-standing methods used to maintain the quality of manufactured product in the discrete parts industries. Their use in the process industries, of which mining is one, requires some care owing to the continuous nature of ore extraction and its variable properties._x000D_
The tools can be used for problem diagnostics and as early warning systems._x000D_
In common practice many professional staff, in attempting to get a perfect reconciliation between expected and observed results, try to explain away the error or bury it completely. The methodology advocated here requires a different mindset because the error must be given pre-eminence for lasting improvement to be realised.