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VIF of Descriptors 

The command Tools > VIF of Descriptors... supports the detection of multicollinearities by means of the variance inflation factor (VIF). The user has to select the variables to be included by ticking off the corresponding check boxes. In general one starts with the selection of all variables, and proceeds by repeatedly deselecting variables showing a high VIF. Ideally, the VIF values should be below 10. As the calculation of the VIF can be quite time consuming, you may choose to use only a random sample of 1000 pixels to calculate the VIF. This increases the speed of calculation considerably, even though the accuracy of the VIF values is degraded. However this should be sufficient to get a rough overview.
For descriptor sets with less than 25 spectral descriptors the calculation of the VIF values is performed automatically upon following any change of the selected descriptors. If a set contains a higher number of descriptors the user can decide when to calculate the VIF values by clicking the "start the calculation" button ().
