Variofit: The variofit application is used to fit model semivariograms to experimental and jackknifed experimental semivariograms (Generated by vario). This can be done manually or automatically using least-squares regression or latin-hypercube sampling techniques. Ergodic variations of the model semivariogram from simulation series may also be evaluated.

Here a Gaussian model is fit to the experimantal semivariogram. Click for full size image
Up to four nested structures, plus the nugget, can be modeled. Click for full size image
After the model semivariogram has been used to grid the sample data, it is often a good idea to calculate a experimental semivariogram using the new grid data. Here, experimental semivariograms for ten conditional indicator simulations are display (red dots), the mean model (yellow dashed line), and the model semivariogram (blue line) used to calculate the grids. An exact match is not expected, but if there is a large deviation, the reason may be worth investigating. Click for full size image
If it is necessary to model a site using a jackknifed experimental semivariogram, it is best to use a range of model semivariogram, and calculate multiple grids. Variofit can calculate a range of models. This is a good idea, because 1) a sensitivity analysis can be preformed, and 2) any model passing through the earror bars is a valid model; attempting to grid the data using one model semivariogram would ingore the uncertainty know about data quality. Click for full size image

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