Computes the Fleiss' Kappa value as described in (Fleiss, 1971).
Fleiss' Kappa is a statistical measure for assessing the reliability of agreement between
a fixed number of raters when assigning categorical ratings to a number of items or classifying items.
public static String getInterpretation(float kappa)
Landis and Koch (1977) gave the following table for interpreting κ values. This table is
however by no means universally accepted; They supplied no evidence to support it, basing it
instead on personal opinion. It has been noted that these guidelines may be more harmful than
helpful, as the number of categories and subjects will affect the magnitude of the value.
The kappa will be higher when there are fewer categories. (Wikipedia)