ON A CONTROVERSIAL METHOD FOR MODELING A COREGIONALIZATION

This paper reviews two alternative approaches for modeling the (cross) variograms in a coregionalization: (1) fitting the traditional linear model of coregionalization, or (2) deducing the cross-variogram model as a linear combination of prior direct (auto) variogram models while checking the Cauchy-Schwarz inequalities. We show that the second approach has no practical advantage over the traditional one and may not be valid if more than two variables are involved. In such case, Cauchy-Schwarz inequalities are necessary but not sufficient conditions for validity of a coregionalization model.