i got a use of the treemap, it's for a helpdesk ticket analisys.
Each ticket opened by the helpdesk have a subject on severla level, examples
Software / Microsoft Office / excel / macro / problem descriptions
Hardware / computers / hard drives / problem deswcription
Hardware / printer / tray / problem description
here we have hundred or thousands of open tickets, and the target is to know wich topics are mostly opened then you need to do folowing :
put in dimensions the subject, with only 1 level per dimension, per example dimension 1 will be the 1st level subject (Software OR Hardware), and the second dimesion the next level , etc (the more dimensions you put, the more you can later dig)
in the measure put what you like to compare, it can bee the average open time , number of calls for the topics
This Treemap is useful to dig into the information, here the larger the surface will be , the more attention it need to get, and you can select one subject a time to get more granularity So, if you want more precise information on the subject you have to enlarge an area that's why, when you select an area it zoom on this only area.