Dear Dr. Rocchini: Well, my first reaction is that R squared is not an appropriate measure for correlated data. Secondly, such a large area may well have an underlying trend which should be removed before kriging is attempted and lastly the number of observations seems very small if that is the only data layer available.
Sincerely Russell Barbour Ph.D. Research Associate in Applied Mathematics Vector Ecology Laboratory Yale School of Medicine 60 College St. Rm 600 New Haven CT. 06520 TEL: 203 785 2394 FAX 203 785 3604 email: [EMAIL PROTECTED] Quoting [EMAIL PROTECTED]: > I've made an interpolation by IDW, Spline and ordinary kriging and > a cross-validation for all methods. > When I make a regression between predicted and measured values I reach an R2 > of 0.0109 (spline), 0.006 (kriging), 0.0006 (idw), namely very flat curves > (lines). > What could I do? I think I'm using a small number of input values (62) for > the area that I'm considering (4000 km2). > Thanks > Duccio Rocchini > > Dr. Duccio Rocchini > Dpt.of Env. Sci. > University of Siena > www.rocchini.net > > > > > > -- > * To post a message to the list, send it to [EMAIL PROTECTED] > * As a general service to the users, please remember to post a summary of any > useful responses to your questions. > * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and > "unsubscribe ai-geostats" followed by "end" on the next line in the message > body. DO NOT SEND Subscribe/Unsubscribe requests to the list > * Support to the list is provided at http://www.ai-geostats.org > -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org
