Table 3.

Brief definition of terms used in spatial statistics and geostatistics [see for example (Mulla and McBratney, 1991) for more detailed information].

Term	Definition
Spatial autocorrelation	Property of a spatially structured variable such that observations collected close to each other are more similar (or less similar, for negative autocorrelation) than observations from more distant samples
Range	In geostatistics, this is the distance within which observations show significant autocorrelation and beyond which observations can be deemed truly independent
Nugget effect	In geostatistics, this indicates the existence of variability at scales smaller than the minimum inter-sample distance. This variability can originate from measurement or sampling error, or from the existence of small-scale spatial variability in the measured variable