[ai-geostats] Re: Geostats Scam?

[Isobel Clark]

And don't forget the 27 page article by Philip & Watson "Matheronian geostatistics - Quo Vadis?" in Mathematical Geology, vol 18, pp 93-117. 24 pages on what a confidence trick geostatistics is.

 

There are response letters in that volume and later volumes from members of the geostatistical community. A wonderful example of neither side listening. Bear in mind when you read this article that it was not refereed before publication.

 

In fact, this is a very good paper to illustrate the enormous difference which can occur when you approach a problem from a completely different direction.

 

What baffled me for a long time is that their argument is that where you have more data, you have more variability and therefore less confidence in your estimates. This seemed to me, set in my ways as a classical statistician as counter-intuitive. Some years later I was discussing a possible geostatistics study with a colleague who was a land surveyor when the penny dropped! P&W are geographers. They can SEE the surface they are trying to map. So they MAKE more observations where the land surface is more variable. Completely logical. Where they have fewer observations, it is because the surface is flat and they are confident in their estimates. And vice versa.

 

Matheron developed geostatistics, just as econometricians and statisticians developed time series analysis -- for surfaces and series which cannot be seen. More data does not mean less confidence in local variability, it just means more data.

 

As you said, Steve, if geostatistics does not make sense for your application or the results don't make sense in the context of you data, there are lots of other things you can do. And, if you are happy with using geostatistics, keep it simple!

 

Isobel

http://www.kriging.com/courses

Stephen Henley <[EMAIL PROTECTED]> wrote:

Hi Mach -

Jan Merks isn't the only one who has questioned the fundamentals of
geostatistics. You might also like to look at the work of Robert F. Shurtz.
Perhaps the most interesting is a slim volume published by the Mining &
Metallurgical Society of America, "A Geostatistical Monograph" (in 1997, I
believe, though the book isn't dated). This is in the form of a debate
between Robert Shurtz (criticising geostats) and Harry Parker (defending
geostats).

If you want alternatives to geostats, there are plenty on offer. Problem is,
of course, that after thirty-something years geostatistics has become the
'accepted wisdom' in the mining community, and you have an uphill struggle
to justify using any other method. Unfortunately, also, any geostatistical
practitioner who uses a fancy new nonlinear kriging method has much less of
a struggle even if that new method is little better than alchemy. Linear
kriging does actually have some nice mathematical properties if its
assumptions are satisfied and when used properly ('best linear unbiased
estimator' and all that) but what many users seem to forget is that, as soon
as they tweak the method, they lose some or all of these properties. In my
opinion many of the more exotic variants of kriging are worse than using
non-geostatistical methods because they encourage - wrongly - a belief that
they are in some ways superior simply because they are known as "xxxxx
kriging".

- Steve Henley

================================
Dr Stephen Henley
Resources Computing International Ltd
185 Starkholmes Road
Matlock, Derbyshire DE4 5JA, UK
+44(0)1629 581454
Skype: silicondale
[EMAIL PROTECTED]
================================


----- Original Message -----
From: "Mach Nife" <[EMAIL PROTECTED]>
To:
Sent: Tuesday, February 07, 2006 6:58 PM
Subject: [ai-geostats] Geostats Scam?


> Hi,
>
> This guy (Jan W Merks) seems to devote his life trying
> to prove that Geostatistics is a scam... If it's true
> I'm gonna start looking for alternatives.
>
> http://www.geostatscam.com
>
> Anyone has a point of vue on this?
>
> machnife
>
> __________________________________________________
> Do You Yahoo!?
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