Volume Change Expression

[#1]

Hello,

I am trying to calculate a Volume Change metric for a column graph.  An abbreviated version of my table looks like this:

Geography          Time Period               Target                Volume

Boston                 QTD                          ONC                    33     

Boston                 1 Month                     ONC                    21

Boston                 3 Month                     ONC                    34

Boston                 QTD                          OTHER                23

Boston                 1 Month                   OTHER                17

Boston                 3 Month                   OTHER                22

New York             QTD                         ONC                    43

To achieve a total volume metric, my expression looks something like this: 

     =sum(Volume)

But now I want to do a Volume Change metric: (Current Time Period Volume - Prior Time Period Volume) / Prior Time Period Volume

How would I go about achieving such an expression with my current table setup??

I have a feeling that I would need to add another column for 'Previous Volume' but I do not really want to do this.

Any/all help is most appreciated.

Thank You!!

[JonnyPoole]

Duplicate post / please close