Frequency

In statistics the frequency (or absolute frequency) of an event $$i$$ is the number $$n_i$$ of times the event occurred in an experiment or study.

Types
The relative frequency (or empirical probability) of an event is the absolute frequency normalized by the total number of events:


 * $$ f_i = \frac{n_i}{N} = \frac{n_i}{\sum_j n_j}. $$