This works but the leap year kind of messes it up. Create a calculation called 'Days Since Today':
Then create this calculation ''Last 12 Months Value':
IF [Days Since Today]<=366 THEN [Value] END
Note: Every other year apart from leap years this calculation would be: IF [Days Since Today]<=365 THEN [Value] END
Finally create a calculation for the value you're after:
(AVG([Last 12 Months Value]))+ 1.5
This does return 3.81 but again I'm not sure how you're going to work around the leap year problem... See the attached workbook.
Avg of L12 Months + 1.5.twbx 9.6 KB
I created calculated fields for the count and the sum.
For trailing 36 months, you can change -12 to -36.
Please let me know if this helped.
TTM_Sample_Mia.twbx 13.4 KB
Stephen -- thanks so much for that, it worked like a charm!
Great, glad I could help!