Adobe ECID over visitorID

[PD10]

We started migrating from visitor ID to ECID, but for some reason we see a drop of visitors by around 20% for one of our brands. We are unable to find that why is that happening if anyone could help?

[eric-hansen-wgu]

I'm missing enough information to properly answer your question, but where I've seen this happen is when First Party Cookies are not implemented for the Experience Cloud ID Service on that specific domain.

My first recommendation would be to look at the tracking server setup on the site for the brand that dropped by 20%. If the tracking server points to a different domain than the site, then it will be treated like a third-party cookie provider and thus be blocked.

For example, if I visit "brand2.com" and the tracking server points to "metrics.brand1.com", then the mismatch would cause the cookie blocking and potential drop in visitors.

Sometimes, switching to first party cookie tracking will reduce visitor counts because ECIDs are persisting for longer. So that's another avenue to explore.

[FarazHusain · Accepted solution]

If you're migrating from s.visitorID to ECID and noticing a drop in overall unique visitors, I believe this is quite possible as there is no mapping between s.visitorID and ECID. If you were previously using s.visitorID, and now that has been removed or migrated. ECID sees all visitors as new, because it doesn’t inherit the old s.visitorID value. That means returning users now get a new ECID -> counted as new visitors, not tied to prior sessions. And if you're comparing with historical data where s.visitorID was persistent -> you'll see a drop in deduplicated visitors.