>Hi > >I was investigating my data and it is possible to identifie areas of zeros on the outside limits of the distribution, so it can be possible to model the spatial behaviour in two steps. > >My guess is that I can simple reduce the kriging area to leave the zero area out. > >My doubt is how to model boundaries. I'm sure this is a common problem, so if you can give me some references I'll look forward to find them. > >Thanks and regards > >EJ
Intrinsic geostatistics, the theory based on random functions, does not allow for 'boundary effects'. There should be no interaction between the random variable and its field (in practice, no decrease of density near the borders). On the other hand, transitive geostatistics, the theory based on purposive randomization, does allow for border effects and estimation of boundaries, which may fall anywhere between zero and non-zero observations. The difference between intrinsic and transitive geostatistics is as basic as the difference between model-unbiased and design-unbiased statistical inference. See Petitgas. 1993. Geostatistics for fish stock assessmens: a review and an acoustic application. ICES J Mar Sci 50:285-298. Petitgas and Lafont. 1997. EVA2: estimation variance. Version 2. A geostatistical software on Windows 95 for the precision of fish stock assessment surveys. ICES CM 1997/Y:22. Rubén http://webmail.udec.cl -- * 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
