Hi Stefano, First, I am not sure that stochastic simulation is necessary in your case since you seem to be only interested in what I would call a measure of local (or location-specific) uncertainty. MultiGaussian kriging would in theory give you exactly the same results at less computational cost...of course these days kriging doesn't look as "sexy" as simulation... To validate the results, I would use the concept of accuracy plot introduced by Clayton Deutch. This concept and others are explained in the paper: Goovaerts, P. 2001. Geostatistical modelling of uncertainty in soil science. Geoderma, 103: 3-26. <http://www.terraseer.com/training/geostats/geoder01.pdf> that you can download from my webpage. Of course, you might also want to check the reproduction of target statistics, such as histogram and variogram, but again it seems that in your case your focus is on these probabilities of exceeding a particular threshold. I discuss these issues in another publication: "Goovaerts, P. 2006. Geostatistical modeling of the spaces of local, spatial and response uncertainty for continuous petrophysical properties. Chapter in book Stochastic Modeling II published by the American Association of Petroleum Geologists"... and I could send you a copy if you are interested... An executable to compute the accuracy plot can be downloaded from: http://ekofisk.stanford.edu/SCRFweb/GSLIB/added.html Cheers, Pierre Pierre Goovaerts Chief Scientist at BioMedware Inc. Courtesy Associate Professor, University of Florida President of PGeostat LLC Office address: 516 North State Street Ann Arbor, MI 48104 Voice: (734) 913-1098 (ext. 8) Fax: (734) 913-2201 http://home.comcast.net/~goovaerts/
________________________________ From: [EMAIL PROTECTED] on behalf of Stefano Pegoretti Sent: Tue 7/25/2006 10:38 AM To: [email protected] Subject: AI-GEOSTATS: validation of Simulation Hallo! I'm a Ph.D. students who works with Indoor Radon Data, and it's the first time I join this list. I've a question for you: after post-processing several Sequential Gaussian Simulation to obtain a probability map of exceeding a given threshold, can someone suggests me a "clever" way to "validate" the results? (of course, I've a "second" dataset of measurements to use in this part of the work ; variography and sgs "do not know" this data...) Thanks a lot and best regards, stefano + + 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/ + + 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/
