Counting Average Headcounts

[DH3612]

Hi all. 

OK, having done some research and there seems to multiple different ways to get the same result in PowerBI. My old way was to have a 3 tables, leavers/starters/actual headcount, and then do my calculations off that, but trying to keep it simple and I thought one table with all staff on it leavers joiers etc all on the one table. 

If Attrition = Leavers in last 365 days/Average staff over the last 365 days

then how do I work out the average staff?

The table includes the following:

Name: Staffmaster

Columns that would be useful:

Start Date (this is the date the employee started)

End Date (this is the date they left)

Name or Staff ID (either would be useful for counting the numbers)

What could I do to work out the average number of staff who were employed during the last 12 months?

[lbendlin]

Average by what? By month? By day?

Please provide sample data (with sensitive information removed) that covers your issue or question completely, in a usable format (not as a screenshot). Leave out anything not related to the issue.
If you are unsure how to do that please refer to https://community.fabric.microsoft.com/t5/Community-Blog/How-to-provide-sample-data-in-the-Power-BI-...
Please show the expected outcome based on the sample data you provided.

If you want to get answers faster please refer to https://community.fabric.microsoft.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447...