Tuesday, January 1, 2013

Abuse of Statistics

My take on Abuse of Statistics was put in print in March 1992. It didn’t end up in CIM Bulletin but in CIM Forum. That’s where “Articles of a controversial nature” tend to end up. Merks and Merks in 1991 had shown how to test for spatial dependence by applying Fisher’s F-test to gold grades of ordered rounds mined from a drift. What a pity that geostatisticians in the 1990s didn’t test for spatial dependence between measured values in ordered sets. It is imperative in mineral exploration, mining and mineral processing that degrees of freedom be counted. On-stream analyzers measure and monitor metal grades of mill feed and tailing! That’s why confidence intervals and ranges for metal contents and grades are easy to derive.

So it came about that CIM Bulletin had decided to print in CIM Forum a technical brief on Abuse of Statistics in 1992. But why then had Armstrong and Champigny’s “A study on kriging small blocks” seen the light in CIM Bulletin of March 1989. Why was Abuse of Statistics published in CIM Forum? Why was placing distance-weighted averages AKA kriged estimates between measured values deemed sound science in CIM Bulletin? Why do geostatisticians not test for spatial dependence between measured values in ordered sets? Why are degrees of freedom ignored? Simple questions but still no answers! 

Dr W D Sinclair, Editor CIM Bulletin, brought up CIM Forum in his letter of September 21, 1992. He was aware that I have served on various standard committees since 1974. Dr F P Agterberg was his Associate Editor in those days. Both were scholars with the Geological Survey of Canada. They agreed that CIM Forum was a fitting format but that my article should pass rigorous scrutiny. Dr Agterberg wanted to know when H G Wells had said: “Statistical thinking will one day be as necessary as the ability to read and write”. Surely, one cannot be rigorous enough when entrusted with peer review for CIM Forum. Was it Agterberg who had approved Armstrong and Champigny’s study in 1989? Or was it perhaps David himself?

It was in Darrell Huff’s 1954 How to Lie with Statistics where H G Wells’s quote was printed ad verbatim. Huff had also referred to Disraeli’s famous lament: “There are three kinds of lies: lies, damned lies, and statistics”. But where had Huff found so much praise for statistical thinking? I had been reading Sherborne’s Another Kind of Life. I tried to contact Dr Sherborne and was pleased he did respond. He attributed Wells’s quote to Samuel Wilks’s 1954 presidential address to the American Statistical Association. It does have an extensive website. Wilks had strung together a rather rambling train of thought whereas Wells was much more frugal with words.

Dr Michael Sherborne has tracked Wells’s train of thought to page 204 of Wells’s book Mankind in the Making: “The great body of physical science, a great deal of the essential fact of financial science, and endless social and political problems are only accessible and only thinkable to those who have had a sound training in mathematical analysis, and the time may not be very remote when it will be understood that for complete initiation as an efficient citizen of one of great new complex world-wide Stats that are now developing, it is necessary to be able to compute, to think in averages and maxima, as it is now to be able to read and write.”

H G Wells

At the same time a budding geologist in Algiers did not know how to derive length-weighted average lead and silver grades determined in core samples of variable length. In fact, he even thought he was working with applied statistics. In time Professor Dr Georges Matheron stripped the variance off the distance-weighted average, called what was left a kriged estimate to honor D G Krige. Next, he praised what he had cooked up and decided to call it the new science of geostatistics. It is a fact that Matheron’s new science is as doomed as the dodo once was!

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