Calling a Column from a SUMMARIZE() Function

HI j_ocean ,

If you want the calculation to be  dynamic, the approach would be to use a virtual table in  a measure instead of using physical tables which update only upon data refresh or when the formula changes and then use the X functions  to aggregate the values within that virtual table.
Below sample formula summarizes the measure Total by [Date] in Dates table. Please note that the fact table could have more than one row for each date. AVERAGEX is then used to get the average of Total_ column within the virtual summary table.

Daily Average (Summarize) = 
AVERAGEX (
    ADDCOLUMNS ( SUMMARIZE ( Dates, Dates[Date] ), "Total_", [Total] ),
    [Total_]
)

 
I would have given a sample formula for your use case but it isn't clear what you mean by "standard deviation at the quarterly level, based on the monthly". You also mentioned average but average of what?

It is always a good idea to provide a sample data (not an image) and from that sample data the expected result.