Hello Digby,

By sampling problem, I meant aspects of the collection + preparation of the 
eight samples from the one ton sample.  From Kevin's description this all 
occurs at the laboratory. Thank you Isobel for your clear breakdown of the 
issues.   The geologist in me was trying to draw attention to consideration of 
the sampling issues as well as the statistical. 

Sorry to worry you with my statement, Isobel.  I was thinking that this would 
be the case if the bulk sample was truly homoginised. But as you rightly point 
out it is unlikey to be so in most crushed gold deposit samples.

David Reid


-----Original Message-----
From: Digby Millikan [mailto:[EMAIL PROTECTED]
Sent: Friday, 13 May 2005 7:34 PM
To: ai-geostats; Reid, David W
Subject: Re: [ai-geostats] Treatment of gold outliers from belt samples


David,

A few questions,
How would you determine the number of samples? 
When you say sampling problem, do you mean
problems in the laboratory?

btw Michel David's example of  the use of sichel
t-estimator is the use of five samples from Harmony
Mine. He also goes onto discuss pro's and con's
of having 5 samples 

  i.e.

  arithmetic mean of 5 samples       
              1195 in-dwt  (47.2 gram.metres)
  sichel mean of 5 samples
               894 in-dwt  (35.3 gram metres)
  mean derived from 5,170 samples    
               618 in-dwt  (24.4 gram metres)

Regards Digby 
 



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