Calculating average over date differences

[umahm1]

Hi guys, 

I have a problem that i am not able to solve and i need your help:

Problem: 

I have a table of dimension_employment for employees that contain departmentID employmentid and employeeid. 

One employeeid can have many employments. 

i have a fact_employee that just counts employees also contains departmentID

What i need to calculate is an average seniority. which is calculated as today-the day employee started divided by amount of employees in department.

my dax measure is: calculate (averagex(datediff(employee start date, today(), day)))

but it doesnt give me the correct result.

How can i make a measure that acutally works ?

[Greg_Deckler]

Please see this post regarding How to Get Your Question Answered Quickly: https://community.powerbi.com/t5/Community-Blog/How-to-Get-Your-Question-Answered-Quickly/ba-p/38490.

Specifically sample data and sample expected output.