Inflation in key metrics when configuring Experience Cloud ID Service extension

[AWalsh1]

We've recently configured the Experience Cloud ID Service extension and have since seen inflation in unique visitor, visits and page view numbers.

In addition we've seen an increase in the proportion of visitors being classified as first time visitors.

The change we made was to configure Opt-In from No to Yes, and then selected just Analytics from the Pre Opt-In Approvals and toggled the Enable IAB option to Yes.

Does anyone have an explanation as to why this would result in the inflation we've seen in our numbers and the shift in proportion counted as first time visitors?

Any guidance would be much appreciated.

[yuhuisg]

ECID is basically used to identify visitors uniquely. But since it uses a different ID mechanism from what Analytics uses by itself, so the same visitor would end up with 2 IDs: 1 ID before you started using ECID, and 1 after you started using ECID. As a result, you should expect such inflation of numbers.

To mitigate this inflation, you can consider contacting Adobe Customer Care to implement a grace period for migrating visitor identification to ECID. See Step 7 at https://experienceleague.adobe.com/en/docs/id-service/using/implementation/setup-analytics#section-7...