12 Months rolling average

Hi , Anonymous 

You need to add a dimension date table like this:

Date = ADDCOLUMNS( CALENDAR(FIRSTDATE('Table'[Date]) , LASTDATE('Table'[Date])) ,"Year_month", YEAR([Date])*100+  MONTH([Date]))

Then update the dax to this:

1212rollingaverage = var currdate = MAX('Date'[Date])
VAR last12months = EOMONTH(currdate, -12)+1
VAR last12monthyearmonth = YEAR(last12months)*100 + MONTH(last12months)
VAR curryearmonth = MAX('Date'[Year_month])
var t = SUMMARIZE(ALLSELECTED('Date'),'Case'[Year_month],"CaseId",[Countcaseid])
var t2 = FILTER(t,[Year_month] >= last12monthyearmonth && [Year_month] <= curryearmonth)
return
AVERAGEX(t2, [CaseId])

If this method does not meet your needs, you can provide us with your special sample data and the desired output sample data in the form of tables, so that we can better help you solve the problem.(You can also upload you sample .pbix [without sensitive data] to the OneDrive and share with the OneDrive link to me ! )

Thank you for your time and sharing, and thank you for your support and understanding of PowerBI! 

Best Regards,

Aniya Zhang

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