The latter is extended to a spatial breakdown point, which depends on the construction of most unfavorable configurations of perturbation. Variogram estimates at different spatial lags are correlated, for the same observation is used for different lags. The correlation structure of variogram estimators is analyzed for Gaussian data, and then extended to elliptically contoured distributions. Its use for variogram fitting by generalized least squares is presented. Simulations are carried out with several types of underlying variograms, as well as with outliers in the data.
Results show that our techniques improve the estimation and the fit significantly.