In excel, I have a column that is calculating a cumulative average of the average values in Column A using the formula =AVERAGE(A$2:A3) in column B.

The values in Column A correspond with my custom calculated field labeled Column A, but when I create a new calculated field for the cumulative average (column B) using the following (I tried runningSum and RunningAvg as I am not sure which I should use), I get an error that nesting aggregate function isn’t allowed:

When I remove the brackets, I get zeros.
I think my problem might have to do with certain limitations imposed on “custom aggregations” within QuickSight because I have not found a way to aggregate a custom aggregation…or something like that?

Could someone help me figure out the right way to do this?

I would like to partition by month using [truncDate("MM",{reporting_period}) ASC]
Also, I am getting an error message that says “nesting of aggregate functions is not allowed”.