"Last week AEM measures 450 account registrations"
How is AEM measuring this?
I am not an AEM expert but my understanding is:
There is a flag in AEM based on the users string that shows that an account registration has taken place?
Where is the absolute truth on account registrations last week? Is it in AEM or some other system? Have you compared the Analytics number to that?
Are you using event serialisation while tracking registrations? If not you should implement that so that registrations will not be double counted.
I'm trying to get to the absolute truth here, i guess the question is which system is correct?
Event serialisation is implemented and confident there is no double counting here.
I'm afraid you're going to have to be the one to tell us where the absolute truth number resides
In terms of registrations, I'm assuming you're collecting personal details that are deposited in a backend system somewhere, correct? How many entries are there during the period you're comparing AEM/Analytics data?