Check, if this is what you need:
(IF NOT ISNULL(count([months_since_activation_exp]))
THEN ([No. of merchants])
END)/(IF INDEX()=1 THEN[Total merchants] ELSE ([Total merchants]-(IF NOT ISNULL(count([months_since_activation_exp]))THEN ([No. of merchants])END))END)
Thanks Deepak !
However the calculation is incorrect.
What this calculation is doing is taking the difference between total active and churned merchants in the same bucket (months_since_activation_exp)
For example, Activation month: Jan 2015, Month 3: The calculation should be: 29/(376-11-11) = 8.2%
whereas what it is doing is: 29/(376-29) = 8.4%
Also I could not use running sum because:
1. I have hidden one bucket "null" which means that the accounts are active hence months since activation expiration is null.
2. Running sum will also take current bucket into consideration.
Could you please advise?