Average amount of payments done by a specific group - set analysis

[#1]

Hi,

I want to find out the avarege amount of payments done by donors that has attrited and has made at least on payment.

Expression/variable name "attrited" =FadderskapStatus=Stoppdato

Expression/variable name "at least one payment" =InnbetalingsStatus=Har innbetalt

Expression/variable name "payment" =NumericCount (#ReskontroInnbetaltBeløp)

Can anyone help me out With a set analysis here?

Best regards,

Christian

[#2]

I tried this one, it does not work even when I don't include

the "at least one payment" =InnbetalingsStatus=Har innbetalt condition

=(Count({<InnbetalingsStatus={'Har innbetalt'}>} [Antall innbetalinger])) / NumericCount (#ReskontroInnbetaltBeløp)