[R-sig-Geo] Cokriging unbiasedness condition

[Edzer Pebesma]

With the usual ones I refered to (what I believe is) ordinary cokriging:
each variable has sum of weights for the variable itself is 1, sum of
the weights for all other variables is 0.

On 04/06/2011 01:59 PM, Piero Campalani wrote:
> Thank you.
> So that means that e.g. with ordinary cokriging, the one condition "sum of
> all coefficients equal 1" is used, and not e.g. the (n+1) nonbias conditions
> by which the coefficients of the target variable sum to 1, whereas the
> coefficients of the n secondary variables sum to 0 ?
> I'm sorry, I'm not aware of what the "usual ones" are unluckily. :)
> 
> Regards.
> 
> On 6 April 2011 13:02, Edzer Pebesma <edzer.pebesma at uni-muenster.de> wrote:
> 
>>
>>
>> On 04/06/2011 11:43 AM, piero campa wrote:
>>> Dear list and dear Edzer,
>>> I was wondering which unbiasedness condition(s) is/are used in the
>>> predict.gstat function when cokriging methods are called.
>>
>> The usual ones; if no trend function is specified (...~1), then an
>> unbiasedness condition for the mean value is used; if some trend
>> function is specified the conditions extend to the mean parameters.
>>
>> Function gstat() has a merge parameter that allows one to join the
>> unbiasedness condition for any two parameters to one.
>>>
>>> Thank you in advance.
>>> /Piero
>>>
>>> --
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>>
>> --
>> Edzer Pebesma
>> Institute for Geoinformatics (ifgi), University of Münster
>> Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
>> 8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
>> http://www.52north.org/geostatistics      e.pebesma at wwu.de
>>
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> 

-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de