Dear Digby Millikan, > , and was curious as to weather other > values could be used or only the mean was appropriate.
We distinguish an empirical and a theoretical variogram: The theoretical variogram is the expected value of the squared difference. The empirical variogram is the mean of the actually observed squared differences. In principle the correct value would be the value of the theoretical variogram. However the theoretical value is not observable and thus we take the best approximation we have, e.g. a value from a variogram model fitted to the means of the observed values. Other estimators, e.g. more robust ones, have been proposed e.g. by Cressie, but the use of the mean is still state of the art, when robustness is not important. When you are so interested in the basics of geostatistics it might be a good idea to work through one the books focusing more on the theory. I personally found the book of Cressie very helpfull in this direction, but also the books of Wackernagel and Chiles/Delfiner might give a more complete view to the mathematical background. Best regards, Gerald Am Freitag, 15. September 2006 10:27 schrieb Digby Millikan: > , and was curious as to weather other > values could be used or only the mean was appropriate. -- ------------------------------------------------- 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/
