Fano factor

The dispersion index (DI ) or variation factor (Vf) is a measure of mathematical statistics to assess the distribution pattern of dispersion of a probability distribution. The compliance or deviation of the actual distribution of values ​​will be considered with a Poisson distribution.

The distribution pattern can be:

• Random,
• Uniformly or
• Grouped.

Be variance and mean of the elements of a sample, then for the dispersion index:

.

Then, however, this assumption needs to be verified, for example by means of chi - square goodness of fit test.

Application Examples

In ecology can be considered based on plants ( Plant Ecology ), animals or other feature of the vehicle for example the random, uniform or clustered distribution.

The distribution rate of DNA sequence differences between groups of animals can vary greatly from reviews without this index.