One thing that might make this a little easier is to calculate a new dimension instead of new measures. When you have multiple measures, each calculated based on different values of a dimension, it does get very difficult to use them together and do further calculations on them.
I've attached a workbook that demonstrates a slightly different approach. Please take a look and let me know if you have any questions.
Date Comparison Testing.twbx 623.9 KB
thanks for your reply. However this is not going to work for me in this case but it may under other circumstances in the future.
The workbook I had posted was a test workbook so it will not have outlined my end goal on this one.
On the LHS will be my ITEM Departments, Across the tab will be the values for each of my stores - these will be a combo or all of Sales TP (this period), Sales LP (last period), Sales Diff, % Sales Diff, Qty TP, Qty LP, Qty Diff, % Diff.
I can't see how your solution would work for me in this case... (but thanks again)....