Through Time Comparison Counter

[#1]

I am trying to work on a set analysis that counts the number of Employees who had a decreased number in sales from the previous quarter but I am having trouble figuring out how to go about doing this.

So far I have:

sum({$<[Pd_End_Dt]={"*"},Employee_Name={"*"}>}[Sales])-above(sum({$<[Pd_End_Dt]={"*"},Employee_Name={"*"}>}[Sales]))

but am unable to get past this. I've tried the count function but can't seem to get it to work. Ultimately I would like to be able to drill down from Company>Department>Employee but for right now just need the number of employees that decreased.

The table looks something like this:

Pd_End_Dt	Employee_Name	Sales
3/31/2015	A	300
6/30/2015	A	350
9/30/2015	A	200
3/31/2015	B	150
6/30/2015	B	200
9/30/2015	B	200
3/31/2015	C	500
6/30/2015	C	400
9/30/2015	C	300

Any help would be appreciated, thank you!

[sunny_talwar]

Is this calculated each period (in a straight table?) or for the most recent period (in a text box object)?

[#3]

I need it to be calculated for each period. The data is updated every month and pulls the last 13 months from a sql table.