Dear AI-list, in which context KED is mostly used? I have found examples of this methodology in the context of soil science and climatology:
Bourennane, H., King, D. and Couturier, A., 2000. Comparison of kriging with external drift and simple linear regression for predicting soil horizon thickness with different sample densities: Geoderma, v. 97, p. 255-271. Bourennane, H. and King, D., 2003. Using multiple external drifts to estimate a soil variable: Geoderma, v. 114, p. 1-18. Goovaerts, P., 1999. Using elevation to aid the geostatistical mapping of rainfall erosivity: Catena, v. 34, p. 227-242. Hudson, G. and Wackernagel, H., 1994. Mapping temperature using kriging with external drift: theory and an example from Scotland: International Journal of Climatology, v. 14, p. 77-91. Martinez-Cob, A. and Cuenca, R.H., 1992. Influence of elevation on regional evapotranspiration using multivariate geostatistics for various climatic regimes in Oregon. Journal of Hydrology 136, 353–380. Are there other interesting references for this methodology in the same or other application fields? Best wishes, ___________________________________________________ Els Verfaillie, PhD student Renard Centre of Marine Geology - Ghent University Krijgslaan 281-S8 B-9000 Gent - Belgium tel: +32-9-2644573 fax: +32-9-2644967 e-mail: [EMAIL PROTECTED] http://www.rcmg.ugent.be/ ___________________________________________________ -----Original Message----- From: Pierre Goovaerts [mailto:[EMAIL PROTECTED] Sent: donderdag 30 juni 2005 16:54 To: Recep kantarci; ai-geostats@unil.ch Subject: RE: [ai-geostats] modelling trend and kriging type To add to the excellent comments by Edzer and Gregoire, 1. Universal kriging = kriging with a trend. The second terminology has been proposed by Andre Journel who felt that the term "universal" was vague and misleadingly "ambitious". 2. Kriging with an external drift (KED) is mathematically the same as universal kriging (UK). Secondary variables are simply replacing the spatial coordinates used in UK. 3. Regression kriging denotes all the techniques where the trend is modeled outside the kriging algorithm. There are various methods that can be used to model that trend, ranging from linear regression to neural networks. Kriging is used to interpolate the residuals. In practice these techniques have more flexibility than universal kriging in term of modeling the trend: multiple variables either categorical or continuous can be incorporated easily and many sofwtare are available for this trend modeling. The only limitation is that the trend is modeled globally (i.e. the regression coefficients are constant in space) while in KED the coefficients are reestimated within each search window. Cheers, Pierre Pierre Goovaerts Chief Scientist at Biomedware 516 North State Street Ann Arbor, MI 48104 Voice: (734) 913-1098 Fax: (734) 913-2201 http://home.comcast.net/~goovaerts/ -----Original Message----- From: Recep kantarci [mailto:[EMAIL PROTECTED] Sent: Thu 6/30/2005 9:38 AM To: ai-geostats@unil.ch Cc: Subject: [ai-geostats] modelling trend and kriging type Dear ai-geostats members When the data used has a trend, it is needed to model trend and in this case there exists various types of kriging to apply (universal kriging, kriging with a trend, regression kriging etc). If this is the case, does one should use the same type of kriging or different depending on modeling the trend using coordinates of target variable or using other (namely, secondary or auxillary) variables such as elevation or topography ? That is , are there a dinstinction depending on the type of variables to model the trend while kriging? Best regards Recep _____ Yahoo! kullaniyor musunuz? Istenmeyen postadan biktiniz mi? Istenmeyen postadan en iyi korunma Yahoo! Postada http://tr.mail.yahoo.com <http://tr.mail.yahoo.com/> -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.322 / Virus Database: 267.8.2/29 - Release Date: 27/06/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.322 / Virus Database: 267.8.2/29 - Release Date: 27/06/2005
* By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
