Subtract values from different rows

[RichWyeth]

Hi,

I have a table that tracks company headcount (Headcount_C) and I also have a Month_Year column and a Rolling_Month column.

I would like to know the difference between each month, using either the Month_Year or Rolling_Month.

Rolling Month        Month_Year                  Headcount_C        (Difference)

1                             October 2016               6000                       -21

2                             September 2016          6021                       +3

3                             August 2016                6018                       +1

I am struggling to get this working, I have tried using PreviousMonth and DatesInPeriod, but I can't seem to get the result I want.
I have also surrounded my statement with IF(Headcount_C>0,............

Is there a way to get this working using the rolling month?

All help appreciated.

[v-ljerr-msft]

Hi @RichWyeth,

According to your description, you should be able to use the formula below to create a calculate column in this scenario. (Assume your table is called "Table1".)

Difference = 
VAR rm = Table1[Rolling Month]
VAR hc = Table1[Headcount_C]
RETURN
    hc
        - CALCULATE (
            MAX ( Table1[Headcount_C] ),
            ALL ( Table1 ),
            Table1[Rolling Month]
                = rm + 1
        )

Regards