The value of Kappa coefficient can range between 0 and 1, lower
values mean no correspondence between certain and classified data,
on the contrary, high values describe a good correspondence between
certain and classified data. Usually values greater than or equal to 0.75
are considered from excellent to good results, while those less than or
equal to 0.4 are considered poor. Kappa Index is often used to compare
results of classification algorithms and different methodologies; for a
reliable comparison it is appropriate, however, to compare classifications
with similar classes.