Unscrambling the French sampling school

Dr Pierre M Gy (1932- ) threaded together the theory and practice of sampling particulate materials. Gy’s gift to mankind ended on my desk about Christmas 1979. I had never ordered it! Yet, Gy’s invoice had come along with his work. Elsevier Scientific Publishing Company had printed it as Sampling of Particulate Materials, Theory and Practice. It had done so as Developments in Geomathematics 4.

Elsevier has ranked Dr F P Agterberg’s Geomathematics as Volume 1 in this series. Dr M David’s Geostatistical Ore Reserve Estimation was ranked as Volume 2. I kept track of what Elsevier Scientific Publishing Company had deemed fit to print before 1979. I am keeping my favorite textbooks close together. William Volk’s Applied Statistics for Engineers is my favorite. Of course, Volk’s work ought to be studied in detail. Degrees of freedom should be counted whenever unbiased confidence intervals and ranges for contents and grades ought to be reported!

Dr Gy never got into partitioning sets of primary increments into pairs of interleaved primary samples. A single degree of freedom is awarded when a pair of interleaved primary increments is selected but one is still better than none. Degrees of freedom abound in Gy’s work but fail to show up in his Index. Gy refers to “degenerate splitting processes” and “degree of representiveness” but neither is defined in his very own textbook. Professor George Matheron stripped the variance off the distance-weighted average AKA kriged estimate.Functions without variances? Good grief!

Dr Gy postulated ad verbatim under Introduction on the first page:

“The failure of mining or metallurgical undertakings can nearly always be traced back to the confusion between “specimens” on the basis of which no sane financial decision should ever be made and “samples” known to be representative of the object to be valued (ore body, shipments of ores or concentrates, etc..) within the limits of a certain confidence interval that can be estimated and relied upon. In other word, the failure of what is aptly called a mining or metallurgical “venture” can nearly always be attributed to unaccountable sampling errors”.

Dr Pierre M Gy does refer to Geostatistical Ore Reserve Estimation. It was Dr Michel David who had put it on paper. All it took was to strip the variance off the distance-weighted average and call what was left a kriged estimate. Elsevier Scientific Publishing Company deemed it fit to print and had done so in 1977.


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