The Semivariogram

The semivariogram is the basic geostatistical tool for visualizing, modeling, and exploiting the spatial autocorrelation of a regionalized variable. As the name implies, a semivariogram is a measure of variance. Although procedures exist for modeling the semivariogram through iterative or least-squares methods, practitioners recommend actual inspection of the observed semivariogram and the fitted model. A properly fitted model then allows the computer program to calculate linear estimates that reflect the spatial extent and orientation of autocorrelation in the variable to be mapped.