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# Set Statistics

The calculation of mean vectors for Sets can be associated with:

• Confidence or Variability cone angles
• Fisher dispersion constants

Confidence and Variability cones are displayed with the Edit Sets dialog.

Confidence limits, Variability limits, and Fisher Coefficients for all Sets can be found listed in the Dips Info Viewer.

## Confidence Limit

This angular value reflects confidence in the MEAN within a specified degree of certainty. For example, a 68% confidence cone indicates that the true mean lies within the cone angle of the calculated mean, with a 68% confidence. This feature gives an indication of the reliability of the sample, or if the sample is big enough.

## Variability Limit

This value reflects the natural variability of the data, assuming that the mean is correct. A 68% variability indicates that any pole, selected from the population represented by the mapped sample, has a 68% probability of falling within the variability cone. This feature can be used for probabilistic stability studies (for example, see Tutorial - 08 Kinematic Analysis (Toppling), Tutorial 09 - Kinematic Analysis (Planar Sliding), and Tutorial 10 - Kinematic Analysis (Wedge Sliding)).

## Fisher Dispersion Coefficient

A Fisher Dispersion Coefficient "K" is automatically calculated for each Set. A larger "K" indicates a tighter cluster.