The statistics returned are:
- number of unique visitors
- number of visits
- number of actions
- maximum number of action for a visit
- sum of the visits' length in sec
- count of bouncing visits (visits with one page view)
For example if $dimension = 'config_os' it will return the statistics for every distinct Operating systems
The returned array will have a row per distinct operating systems,
and a column per stat (nb of visits, max actions, etc)
'label' Metrics::INDEX_NB_UNIQ_VISITORS Metrics::INDEX_NB_VISITS etc.
Linux 27 66 ...
Windows XP 12 ...
Mac OS 15 36 ...