DAX: Rolling 12-month turnover rate but trying to average monthly distinct counts

[saltesc]

Hi all,

I'm attempting to do a simple 12-month turnover rate:

Employee Separations / Avg Employee Headcount over 12 months

However, the dataset I have has employees appearing multiple times as they are split over multiple roles. Initially, to overcome this issue for getting my rolling headcount, I was able to create a measure using DISTINCTCOUNT() on employee IDs with Hire Date and Separation Date filters over my rolling 24-month report:

Active Headcount =
CALCULATE (
    DISTINCTCOUNT( EmpData[Unique ID] ),
    FILTER (
        ALLSELECTED ( EmpData ),
        EmpData[Hire date] < LASTDATE ( 'Calendar'[Dates] )
            && EmpData[Separation process month] > LASTDATE ( 'Calendar'[Dates] )
            || EmpData[Hire date] < LASTDATE ( 'Calendar'[Dates] )
                && ISBLANK ( EmpData[Separation process month] )
    )
)

This works fine, as I see the total headcount as of Year/Month/Day as I drill through. However, trying to get the rolling average of this is proving difficult. If I set up a Matrix in monthly view, it may be easier to understand...

So, here's my headcount figures showing correctly with the aforementioned Measure. I need to get the average of the period (in red) rolling so that it updates each year, month, etc. in the reporting and allows me to calculate my annualised attrition (turnover) rate.

Any ideas much appreciated.

 

[pjmorris]

In my models I frequently use a disconnected calendar and then apply the dates explicitly:
for example: =CALCULATE( DISTINCTCOUNT( EmpData[Unique ID] )/12,
FILTER (EmpData[Hire date] < LASTDATE ( 'Calendar'[Dates] && EmpData[Hire date] >= DATEADD("YY",-1, LASTDATE ( 'Calendar'[Dates] ))))

HTH