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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 leastsquares
regression or latinhypercube 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.
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Up to four nested structures, plus the nugget, can be modeled.
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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.
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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.
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