A study on kriging small blocks


Written by Jan Merks

Topic: Sampling & Statistics

Date: June 16, 2013 19:28

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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Margaret Armstrong and Normand Champigny called on but a few facts to get their small block study going in the 1980s. Following are two (2) facts that underpin their study:

Mine planners often insist on kriging very small blocks
Kriged estimates of very small blocks are over-smoothed

These geostatistical scholars had found out that kriged block grade estimates and measured grades no longer display associative dependence when variogram ranges are less than half the spacing between samples. Good grief! I couldn’t have thought that up even if I were a crafty kriger or a cunning smoother! Surely, geologists and mining engineers didn’t expect kriging to create random numbers! Yet, CIM Bulletin put in print what the authors thought about the rise and fall of kriging variances. Who were the peers who reviewed Armstrong and Champigny’s study? Didn’t they know why the kriging variance rises up to a maximum and then drops off? Who was the Editor of CIM Bulletin in 1989? What did she or he think of the rise and fall of kriging variances? But why did P I Brooker think in 1986 that kriging variances are robust?

Applied Statistics for Engineers


Written by Jan Merks

Topic: Sampling & Statistics

Date: May 16, 2013 22:03

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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William Volk in his Preface pointed out that his take of applied statistics is traceable to a course he had taught in 1951. The McGraw-Hill Book Company published the first print in 1958. Its frontispiece reads: “for Dorothy whose confidence is without limits”. What a touching view on confidence without limits! I bought my first copy in the 1960s when I was working in the Port of Rotterdam. I have placed Jan Visman’s 1947 PhD thesis on coal sampling and William Volk’s Applied Statistics for Engineers side-by-side on the same bookshelf. I have tried to find out more about Volk after we had come to in 1969 but to no avail. I wanted to write a Wiki page about Volk, his textbook, and his grasp of variances as displayed in Section 7.1.4 Variance of a General Function and in Section 7.3 Confidence Range of Variances. I still wonder whether or not Volk was of Dutch decent.

Use and Misuse of Statistics


Written by Jan Merks

Topic: Sampling & Statistics

Date: April 20, 2013 17:52

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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“Statistical thinking will one day be as necessary for efficient citizenship as the ability to read and write.”
H G Wells (1866-1946)

Wells was a prolific writer with a keen sense of rights and wrongs in his life and time. What had inspired him to praise statistical thinking were the works of Karl Pearson (1857-1936), and of Sir Ronald Aylmer Fisher (1890-1962). Pearson worked with large data sets whereas Fisher worked with small data sets. That was what inspired Fisher to add degrees of freedom to Pearson’s chi-square distribution. Thus was born a feud between giants of statistics. Degrees of freedom converted probability theory into applied statistics, and sampling theory into sampling practice. Fisher and Pearson were both outstanding statisticians. They inspired H G Wells and scores of statisticians. Applied statistics shall stand the test of time until our sun bloats into a red giant and Van Gogh’s Sun Flowers are bound to burn to a crisp.

Brownian motion along straight lines?


Written by Jan Merks

Topic: Sampling & Statistics

Date: April 1, 2013 18:04

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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Professor G Matheron didn’t grasp in 1965 how to test for spatial dependence in sample spaces. What he did in 1970 is evoke Brownian motion along straight lines. He was scheduled to speak about it at the University of Kansas, Lawrence, Kentucky. He had taught A Marechal and J Serra all about kriging and smoothing at the Centre de Morphology Mathematique, Fontainebleau, France. Matheron has never explained why he stripped the variance off the distance-weighted average and called what was left a kriged estimate. Neither did The Founder of Spatial Statistics put in plain words why the distance-weighted average had metamorphosed into a kriged estimate. It was not D G Krige who called it a kriged estimate but Matheron! That’s in a nutshell why Professor Matheron could do so much with so little!!

Flunking his PhD thesis


Written by Jan Merks

Topic: Sampling & Statistics

Date: March 14, 2013 18:11

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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Put it on paper; call it a PhD thesis; get it approved! Simple comme bonjour, n’est-ce pas! But the PhD supervisors at Université de Paris Sorbonne did not approve Professor Georges Matheron’s PhD thesis. On the contrary, they wanted to know what I have wanted to know for a long time! The title of Matheron’s thesis was “Les variables régionalisées et leur estimation: une application de la theory des fonctions aléatoires aux sciences de la nature”. How about that? Thank goodness French was my very first foreign language!

What’s wrong with Matheron’s 1965 PhD Thesis


Written by Jan Merks

Topic: Sampling & Statistics

Date: February 20, 2013 19:34

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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Once upon a time a young geologist in Algiers derived the degree of associative dependence between lead and silver grades of drill core samples. What he didn’t derive were length-weighted average lead and silver grades. Neither did he test for spatial dependence between metal grades of ordered core samples. This geologist did do a bit of applied statistics so he called his article Note statistique No1! In time, one of his many dedicated disciples decided to change it to Note géostatistique No1. He did do so after the Internet was born! The same disciple is still the custodian of Matheron’s magnum opus. He may well want to play with Matheron’s new science of geostatistics from the 1950s to eternity. Good grief! That’s long time! And it’s a headache already! The more so since Note géostatistique No28 shows “krigeage” in its title. Did Matheron ever ask Krige whether he wanted his name to become a genuine eponym?

Six Things to Have Before You Call Your Recruiter – Help Them First and They Can Help You


Written by Ralf Weiser

Topic: General

Date: January 29, 2013 20:06

Technical Manager, Aerzen USA Corp.

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cup

Get this document as a PDF download here: “Six things to have” as PDF.

can work miracles for you. That is especially true when you have your stuff together. Unfortunately, more often than not are either called too late in the game, or they are given incomplete information about what they are really supposed to do for you. There are also some people that expect recruiter Superman to show up and just pick up where they left off.

What I call “stuff” can be narrowed down to six very basic criteria. These may be basic, but they are extremely important for you to have in tow before you reach out to a recruiter. In fact, it is so imperative that you should have this all checked off the hiring list before you search for new employees, regardless of which type of placement firm you are using.

Abuse of Statistics


Written by Jan Merks

Topic: Sampling & Statistics

Date: January 1, 2013 23:11

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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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” tended to end up. Merks and Merks in 1991 had shown how to test for spatial dependence by applying Fisher’s F-test to grades determined in ordered rounds mined from a drift. What a pity that geostatisticians in the 1990s didn’t bother to 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 tailings! That’s why unbiased  confidence intervals and ranges for metal contents and grades are easy to derive.

Who else wants a productive and effective meeting?


Written by Ralf Weiser

Topic: General

Date: October 16, 2012 13:42

Technical Manager, Aerzen USA Corp.

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Death by meeting. That may be the cause of death of many a business leader and a lot of corporate folks. Seriously, one important item that gets overlooked by the vast majority of meeting facilitators is the meeting room set up (Click to tweet this).

How a meeting is supposed to feel to the attendees should be on your mind. Seating arrangement, temperature, food, drinks, rest room access, etc impact how your attendees feel about the presentation / work shop you are trying to hold. Ever tried holding a speech in a stone cold room? Good luck with that one.

Effectiveness is largely driven by how people either face their members or the facilitator. A class room setting will not work well if you want the members to have a communication for interpretation or understanding. It just does not feel right.

Setting New Standards?


Written by Jan Merks

Topic: Sampling & Statistics

Date: October 14, 2012 01:06

Mineral sampling expert, consultant, lecturer, author, whistleblower, 'iconoclast', CIM Life Member

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The Bre-X fraud inspired the Toronto Stock Exchange (TSE) and the Ontario Securities Commission (OSC) to set up a task force. Its objective was to take a close look at National Instrument 43-101. The Members of the task force are given in this Interim Report. Mr Morley P Carscallen, OSC’s Vice Chair, and Mr John W Carson, TSE’s Senior Vice-President, took on this task in April 1997. It is a fact that Bre-X’s bogus grades and Busang’s barren rock were made to look by hook and by crook like a resource. But who were the crooks? And who set the hook for Bre-X’s shareholders? OSC’s own qualified persons have yet to grasp the fact that geostatistics is a scientific fraud! Perhaps ironically, it was geostatistical software that made Bre-X’s bogus grades and Busang’s barren rock to look like massive resource!



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