Using Box-Cox, arcsine, and log transformations

Data transformations can be used to make the variances constant throughout your study area and make the data distribution closer to normal. Understanding transformations and trends provides a more detailed discussion of transformations in Geostatistical Analyst.

Use the Histogram Normal QQ plot and Voronoi Map in Exploratory Spatial Data Analysis to try different transformations assess their effects on the distribution of the data. Box-Cox, arcsine, and log transformations discusses each of these transformations in more detail.

Keep in mind that some geostatistical methods assume and require data with the normal distribution of values. (Quantile and probability maps generated using Ordinary, Simple, and Universal kriging, as well as any map generated using Disjunctive kriging and the Gaussian Geostatistical Simulations geoprocessing tool).

Etapes :

1. Choose Kriging/CoKriging under Geostatistical methods in the Geostatistical Wizard method selection window.
2. Click the Next button.
3. Choose the desired transformation from the Transformation type drop-down menu for each dataset to which you would like to apply a transformation.
4. Click Next.
5. Complete the remaining steps in the Geostatistical Wizard to create a surface.

Astuce:

In creating the surface, the Geostatistical Wizard automatically back transforms the predicted values into their original units. There is no need to back transform the values yourself.

To decide which type of transformation might be the most appropriate for your data, go to Explore Data of the Geostatistical Toolbar and choose the Histogram option. Use the Transformation section of the interface to display the histogram after different transformations have been applied to the data. Choose the transformation that makes your data have a distribution that is closest to a normal distribution.