Hi Everyone,

Here is basically the data I am using

Column A - (identifiers) email Addresses
Column B - An exact date

I am counting the number of times that an email address has a date and then minusing the original date to find an average number from the date of the 2nd, 3rd etc. Date to get a number of days between the two events.

I tried the below formula:
=SUMIF(Sheet5!J:J,Sheet6!A3,Sheet5!K:K)-VLOOKUP(A3,Sheet5!J:K,2,FALSE)*VLOOKUP(A3,Sheet5!J:N,5,FALSE)

The SUMIF, counts the dates according to a list of uniques that I created from the original list of email addresses.
Minus the original date * a count of the number of times that email address appears.

However, this gives me wild results and minus numbers which I assume is because of the way the datevalues are done?

Any help you can give would be great!

Thanks,
Gareth