About your question
on heterogeneity in spatial data. Sorry for my very lazy answer but one
elegant way to deal with such heterogeneity is Denis Allard's class kriging.
Gregoire
PS: I just have
checked the ftp server of GIDA which is down at the moment, unfortunately. You
could download the whole file of SIC97 from http://www.ai-geostats.org/events/sic97.htm where his paper is also
published.
