Rolling 3 month average excluding December and currrent month

[Anonymous]

So I've done some research on rolling averages the last couple days. I've been somewhat successful in coming up with a solution but I'm not quite there. I have a date table and a formula to calculate average wait time, which is measured by averaging up a calculated colum. Here's my formula for the rolling average:

Wait Time 3 Month Rolling Average =

CALCULATE (

AVERAGEX ( VALUES ( 'Date Table'[Month] ), [Avg. Wait Time %] ),

DATESINPERIOD ( 'Date Table'[Month], MAX ( 'Date Table'[Month] ), -3, MONTH)

)

Some problems:

1. It doesn't exclude December, but it should

2. I believe it includes the current month in the calculation, but it shouldn't

For example, when February is selected in the month filter, I want the measure to calculate the average wait time from January, November, October.

Please help! Thanks

[amitchandak]

@Anonymous , Try something like

CALCULATE (
AVERAGEX ( VALUES ( 'Date Table'[Month] ), [Avg. Wait Time %] ),
DATESINPERIOD ( 'Date Table'[Month], eomonth(MAX ( 'Date Table'[Month] ),-1), -3, MONTH)
)