Ernst Glatzer and Werner G. Müller
An Interactive Tool for Residual Diagnostics for Fitting Spatial
Dependencies (with Implementation in R)
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There exists a growing number of spatial statistics software
packages covering a broad range of methods including the classical
technique of kriging following variogram fitting (for a review see
e.g. Bivand and Gebhardt, 2000). However, most of these programs
do not contain tools for assessing the fit of particular models of
the spatial dependencies. Based upon a variogram cloud estimation
method proposed in Müller, 1999 we present various techniques
for that purpose and their implementations in an R-package called
vardiag. The paper concentrates on the interactive aspect of
the problem worked out in the dissertation of Glatzer, 2002. For
the interactive exploration of the fit several plots (a map view,
the square-root-differences cloud and two types of residual plots)
are linked. The proposed tool allows brushing of single points or
sets of points in these plots. The selection of points in one plot
is reflected by an automatic selection of the corresponding parts
in the other plots. The program is exemplified on a data set of
chlorid concentrations in the Südliche Tullnerfeld.