Dear list,
I would like to discuss with you about the case study
given in Journel`s book of Mining Geostatistics,
related to the Chapter V.C.4.: Global estimation on a
domain of unknown geometry. The case study is
regarding Ity deposit (p. 439 to 443) where the
estimated block has different size: b1 (N-S direction)
is 20 m and b2 (W-E direction) is 30 m.
When we calculate the variance of global estimation,
in p. 441 mentioned that in this case, the global
estimation variance is calculated as the sum of a line
term and section term. The line term (corresponding to
the N-S lines which have the greatest data density,
b1<b2) measures the extension error of the 58 central
accumulations to their segments (b1=20 m) of
influence.
My question is: what to do if we have the same data
density, for example b1=b2...? which lines direction
we should use to calculate the extension variance of
points in lines term?
The second case is still related to p. 441, mentioned
that when we measure the extension variance of lines
in rectangles term...the nugget effect has no
influence, this is due to the fact that the nugget
constant, regularized over the length L1 (for
example), can be considered as zero because L1 is much
greater than the diameter of the sampling pit, which
is the support on which the constant C0 was defined.
My question is: for which case (the rasio or
comparison of the length of line and diameter of
sampling pit) we should consider that the nugget is
not zero? is there a rule of thumb for this case?
I am waiting for any comments. Thank you.
Regards,
---------------
M. Nur Heriawan
Earth Resources Exploration Research Group
Faculty of Mining and Petroleum Engineering
Institut Teknologi Bandung (ITB)
Jl. Ganesha 10 Bandung 40132 INDONESIA
http://www.mining.itb.ac.id/heriawan
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