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Examine the distribution of your data

Available with Geostatistical Analyst license.

Most of the interpolation methods provided by Geostatistical Analyst do not require the data to be normally distributed, although in this case the prediction map may not be optimal. However, certain kriging methods require the data to be approximately normally distributed (close to a bell-shaped curve). In particular, quantile and probability maps created using ordinary, simple, or universal kriging assume that the data comes from a multivariate normal distribution. In addition, simple kriging models, which are used as a basis for geostatistical simulation (see Gaussian Geostatistical Simulations for more information) should use data that is normally distributed or include a normal score transformation as part of the model to ensure this.

Normally distributed data has a probability density function that looks like the one shown in the following diagram:

Normal distribution example

The histogram chart is designed to help you explore the distribution of your data to determine if you should use a transformation. To learn more about the transformations that are available, see Box-Cox, arcsine, and log transformations and Normal score transformation.

All kriging methods rely on the assumption of stationarity. This assumption requires, in part, that all data values come from distributions that have the same variability. Data transformations can also be used to satisfy this assumption of equal variability. For more information on stationarity, see Random processes with dependence.

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