Dear Dave Miller, I have no reference but a thought:
I think that a crossvalidation is unbiased (for a very complex error to be defined, which is however the same for both approaches) if the interpolation is really done only based on the choosen subsample. However depending on how we perform the crossvalidation there could be a problem with ordinary kriging: If the variogramm is reestimated for each subsample, there should be no problem. But if we estimate the variogram once in the beginning and compare cross validation of an arbitrary preselected Radial Basis Function and a Ordinary kriging with an optimally fitted variogram to the complete dataset. I expect a small bias in favor of Ordinary kriging, because fitting a variogramm is already a kind of "finding the radial function, which will performs best with the given dataset". Best regards, Gerald v..d Boogaart Am Mittwoch, 1. November 2006 10:51 schrieb Dave Miller: > Dear Listers, > > When comparing cross-validated results between Ordinary Kriging and a > variety of Radial Basis Functions, is there a reason that the RBF > cross-validation statistics (e.g. ME, MAE, RMSE) may not be unbiased? > > Any references on this topic would be greatly appreciated. > > Regards, > > Dave > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Dave Miller > GIS Research Assistant > The Macaulay Institute > Craigiebuckler > Aberdeen > AB15 8QH > > tel: +44 (0) 1224 498200 (switchboard) ext. 2261 > tel: +44 (0) 1224 498245 (direct dial option) ext. 2261 > fax +44 (0) 1224 311556 > e-mail: [EMAIL PROTECTED] > websites: http://www.macaulay.ac.uk > http://www.macaulay.ac.uk/LADSS/ladss.shtml -- ------------------------------------------------- Prof. Dr. K. Gerald v.d. Boogaart Professor als Juniorprofessor fuer Statistik http://www.math-inf.uni-greifswald.de/statistik/ B�ro: Franz-Mehring-Str. 48, 1.Etage rechts e-mail: [EMAIL PROTECTED] phone: 00+49 (0)3834/86-4621 fax: 00+49 (0)3834/86-4615 (Institut) paper-mail: Ernst-Moritz-Arndt-Universitaet Greifswald Institut f�r Mathematik und Informatik Jahnstr. 15a 17487 Greifswald Germany -------------------------------------------------- + + To post a message to the list, send it to [email protected] + To unsubscribe, send email to majordomo@ jrc.it with no subject and "unsubscribe ai-geostats" in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list + As a general service to list users, please remember to post a summary of any useful responses to your questions. + Support to the forum can be found at http://www.ai-geostats.org/
