Formula for Cumulative Weighted Mean

[#1]

Dear All,

If I have a simple formula as;

ADB=Sum(NetRevenue) / Sum(AdultNight) which is €70.48 = €7,646,735.88 / 108,498 in this data set.

How will I calculate the Cumulative Weighted Mean of ADB (weight=AdultNight) by Sales Date to visualise "ADB Cumulative Mean vs. Sales Date"

The formula I know can not calculate the weight which puts out the wrong final ADB as €68,51

Tables attached

Many thanks in advance for your help.

[#2 · Accepted solution]

Does this formula return the numbers you want?

Sum(:Name("Sum(NetRevenue)")[1 :: Row()]) / Sum(:Name("Sum(AdultNight)")[1 :: Row()])

[#3]

Yes it does! Thank you.

Is formula

Sum(:Name("Sum(NetRevenue)")[1 :: Row()])

a way of calculating the Cumulative Sum?

If I would change the Sum with Mean would it calculate the Cumulative Mean?

[#4]

Yes.

Mean(:ADB[1::Row()])

should give the same result as your formula

If(Row() == 1,

    :ADB,

    (:ADB Cumulative Mean[Row() - 1] * (Row() - 1) + :ADB) / Row()

)

However, for very large tables your formula would probably be significantly faster, despite the conditional structure, because it does not require extracting a matrix for each row.