What is IDW (Inverse Distance Weighted) Interpolation ?
The Inverse Distance Weighted interpolator is a standard deterministic interpolator that is easy and fast. IDW can be used to compare the benefits of using more advanced functions like those proposed in INTAMAP. The exponent value of IDW, traditionally set to 2 (Inverse Squared Distances) is here selected automatically on the basis of a minimum Root Mean Square Error found from cross-validation (CV). This CV is by default 5-fold CV, i.e. that the data set is split in 5 folds, and the process at the observation locations of each fold are interpolated from the remaining 4 folds. This random splitting in data sets can cause that the best fitted value for the exponent can vary for the same data set.
