This function is mainly used to compute qualitative statistics when there are several events per
statistical unit. Often used for reporting adverse events, medical history or concomitant treatments.
It reports frequencies and percentages according to hierarchical levels of two factors.
Typically, adverse event are classified according to System Organ Class (SOC)
and then sub classified by Prefered Terms (PT). Several observations of a same adverse event can
be observed several times on the same subject.
It's then useful to know how many persons are concerned by at least one of those adverse events
and report the frequencies for each classifications: SOC and PT.
This is exactly what this function does.
For more examples see the website: ClinReport website