Hi Niklas
You'll get better/more detailed
explanations than this, but kriging is what they call an 'exact interpolator' in
that the data values are honoured at their locations (ie: 0 error
variance). As the nugget increases, more distant samples receive a higher
weight and taken to the extreme (pure nugget) the samples receive the same
weight and the estimation approaches a simple averaging. See pp
305-307 of Isaaks & Srivastava's book "An Introduction to Applied
Geostatistics" for the full story...
Cheers
Senior Geologist
From: Törneman Niklas [mailto:[EMAIL PROTECTED]
Sent: Tuesday, 7 March 2006 6:15 AM
To: [email protected]
Subject: [ai-geostats] kriging without a nugget
Hi
All,
I am sort of a
beginner within this field and my question might seem a bit simple. Any help
would be appreciated however.
In commercial all
purpose software's such as SURFER there is an option to exclude the nugget
effect from the kriging interpolation.
The purpose is to
ensure that measured values are honoured at their locations. This seems
understandable to me since the absence of a nugget ensures that the variance is
zero at a distance of zero from the measured point, i.e. the measured
value=interpolated value.
However, in most
projects that I work with (soil pollution problems) there is a significant
nugget effect. My question is simply how the interpolation is affected if the
nugget effect is excluded when in reality there is a clear nugget present in the
data.
One reason for this
question (apart from a personal interest) is that I am trying to motivate the
use of other methods (i.e. SGS) and more specialized software such as SGeMS and
GS+. One good easily explainable motivation for this would be if the above
mentioned methodology of excluding the nugget is inappropriate, which is suspect
that it is.
cheers
Nicholas
* By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm )
* To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
