Daily Year over Year Growth

[#1]

Hi all --

Apparently my brain hasn't been functioning well lately, but I'm having a problem with a year over year growth calculation at a daily level.  I'm doing a transaction count by day in a selected time frame and need to calculate the transaction count growth by day.  I've tried using set analysis to get the transaction count for the same Transaction Date a year ago by using [Transaction Date] = {$(=AddMonths([Transaction Date],-12))} but that just returns 0, however if I set the year in set analysis = Year-1 then I get two sets of rows in the table, one for the select year and one for the prior year. 

Example output should be:

Date	# of Transactions CY	# of Transactions PY	Growth
06/01/2012	5000	2500	1
06/02/2012	5500	3000	.8333
06/03/2012	5423	3123	.7364

Any suggestions or ideas what I'm doing wrong?  I've been staring at it for 2 days and nothing is sinking in.

Thanks!

Leigh Johnson

[swuehl]

You should be able to see your set expression with the expanded dollar sign expansion when not using a label in your expression (i.e. the expression will be used as label). Then hover over the label and look at your set expresssion.

What does

=AddMonths([Transaction Date],-12)

returns in a text box?

Your set expression is evaluated in global context, not in the context of the dimension value. So if you are using Transaction Date as dimension, the current dimension value will not be used within your expression set expression.

[#3]

I managed to get this to work by aggregating over the month and day with the following expression:

aggr(count({$<Year={$(#=Only(Year)-1)