If the skewness of the fish data is causing havoc to your variograms try one of the more "robust" measures, i.e. the family of relative variograms (general/pairwise), or the non-ergodic covariance. Transformation would mask the extreme values which may or may not be very significant to your problem domain. Thereafter krige within a limited search neighborhood or try an indicator approach at various thresholds.
Syed ---- Original message ---- >Date: 02 Oct 2002 12:24:57 +0100 >From: Ernesto Jardim <[EMAIL PROTECTED]> >Subject: AI-GEOSTATS: Log transformation and zeros >To: Mailing List AI-Geostats <[EMAIL PROTECTED]> > >Hi > >I'm analysing fisheries data (number of fish caught per hour) and I have >some 0 values. When I log-trans I have to translate the values by hading >some value. > >My question is which value is the best ? is there any works about this ? > >I usually had 1 so that I get values between 0 and infinite (no negative >value) but I have doubts about it. > >Regards > >EJ > > > > >-- >* 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
