If I understand well, "residuals from KED" is different from "residuals 
from the trend"!

The KED prediction is conditional to the observations, therefore 
includes the trend *plus* the predicted deviation for that specific 
realization. It is in the latter component which anisotropy plays its role.
Once it has been taken into account, the residuals should not show 
anisotropy.

Please, correct me if I am wrong.
Bests
       facu.-


Edzer Pebesma escribió:
> In general, the hope (and expectation) is that detrended residuals carry
> less information in the sense of less structure than the raw data. The
> rate with which this happens varies. I don't see any reasons why
> detrending would "typically" lead to isotropic residuals; it could be
> that the author has experienced this effect a number of times. You might
> want to contact him; I believe he listens on the ai-geostats mailing list.
>
> Tobin Cara wrote:
>   
>> Hello,
>>
>> I was reading in Goovaerts book on Geostatistics for Natural Resources Evaluation that the residuals from KED are typically isotropic. In other words, any anisotropy must be accounted for in the trend model not in the residual semivariogram.
>>
>> Is it the case in practice that anisotropy is never detected when finding the semivariogram with residuals or is it ignored (hopefully not)?
>>
>> Thank you,
>>
>> Cara
>>
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