## AI-GEOSTATS: Estimation of the cross semivariogram

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• Dear list I have a question regarding estimation of the cross semivariogram, given by: gamma(h)=1/2N(h)*sum((z_i-z_j)(y_i-y_j)) where y and z are the two
Message 1 of 2 , Feb 14, 2003
Dear list

I have a question regarding estimation of the cross semivariogram,
given by:

gamma(h)=1/2N(h)*sum((z_i-z_j)(y_i-y_j))

where y and z are the two variables. My question simply is: Do y and z
have to be measured at the same locations in order to estimate the cross
semivariogram ??

Best regards / Venlig hilsen

Søren Lophaven
******************************************************************************
Master of Science in Engineering | Ph.D. student
Informatics and Mathematical Modelling | Building 321, Room 011
Technical University of Denmark | 2800 kgs. Lyngby, Denmark
E-mail: snl@... | http://www.imm.dtu.dk/~snl
Telephone: +45 45253419 |
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• Soeren What you have here is sometimes known as a co-located cross semi-variogram and only pairs of samples with both variables can be included in its
Message 2 of 2 , Feb 14, 2003
Soeren

What you have here is sometimes known as a co-located
cross semi-variogram and only pairs of samples with
both variables can be included in its calculation.

There is a non-co-located semi-variogram (see
Cressie's book for example) which looks like

gamma(h)=1/2N(h)*sum((z_i-y_j^2)

This works best if the variables are standardised
(same mean, same standard deviation) and uses all of
the samples with either variable.

Isobel Clark
http://geoecosse.bizland.com/news.html

--- Soeren Nymand Lophaven <snl@...> wrote: >
Dear list
>
> I have a question regarding estimation of the cross
> semivariogram,
> given by:
>
> gamma(h)=1/2N(h)*sum((z_i-z_j)(y_i-y_j))
>
> where y and z are the two variables. My question
> simply is: Do y and z
> have to be measured at the same locations in order
> to estimate the cross
> semivariogram ??
>
> Best regards / Venlig hilsen
>
> Søren Lophaven
>
******************************************************************************
> Master of Science in Engineering | Ph.D.
> student
> Informatics and Mathematical Modelling | Building
> 321, Room 011
> Technical University of Denmark | 2800 kgs.
> Lyngby, Denmark
> E-mail: snl@... |
> http://www.imm.dtu.dk/~snl
> Telephone: +45 45253419 |
>
******************************************************************************
>
>
> --
> * To post a message to the list, send it to
> ai-geostats@...
> * As a general service to the users, please remember
> to post a summary of any useful responses to your
> questions.
> * To unsubscribe, send an email to majordomo@...
> with no subject and "unsubscribe ai-geostats"
> followed by "end" on the next line in the message
> body. DO NOT SEND Subscribe/Unsubscribe requests to
> the list
> * Support to the list is provided at
http://www.ai-geostats.org

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