[R-sig-Geo] Back-transforming krigged variables

[Edzer Pebesma]

What happens in kigeTg doesn't look that hard. Have you tried?

Ebrahim Jahanshiri wrote:
> Thank you very much.
> However I found no couterpart for that in cokriging. Is there any way to do
> that manually? I mean to get "m" manually?
> 
> On Mon, Mar 1, 2010 at 8:26 PM, Edzer Pebesma <edzer.pebesma at uni-muenster.de
>> wrote:
> 
>> Ebrahim Jahanshiri wrote:
>>
>>> I am wondering if there is any function or option to back-transform the
>>> result of the lognormal kriging in gstat yet.
>>>
>>>
>> You can use krigeTg, which does trans-Gaussian kriging for all Box-Cox
>> transforms; passing it a lambda parameter with value 0, log-normal kriging
>> is used. Pls look at the examples, the back-transformed values have funny
>> names like var1TG.pred.
>>
>> The whole think has been implemented for ordinary kriging only; if someone
>> can point me out a source that describes how to do this for universal /
>> external drift kriging, I'd be happy to look into how to implement it.
>>
>>> Although for simple kriging it is fairly straight forward, that is, it is
>>>
>>> possible to do back-transform using the vector of predicted values and
>>> kriging variances, but for ordinary kriging, it might be difficult because
>>> we dont have lagrange multiplier (according to my web help search) to do
>>> the
>>> back-transformation. I am wondering if there has been any advancement in
>>> that matter?
>>>
>>> thank you
>>>
>>>        [[alternative HTML version deleted]]
>>>
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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
>>
>>
> 

-- 
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