Reporting Identity

Reporting identity is the property-level setting that decides how GA4 recognises the same person across sessions and devices. It chooses from several methods — your own User-ID, Google Signals, device data, and statistical modeling — and combines them in one of two modes: Blended, which uses all available methods, or Observed, which skips the modeling step.

Why it matters

Reporting identity is the hidden lever behind your user count. Because it changes how GA4 de-duplicates people, the same underlying traffic can produce a different number of users depending on which mode you choose. If you've ever wondered why your user total doesn't match another tool's, the reporting identity setting is often the reason.

A concrete example

A visitor reads your blog on their phone in the morning, then opens the same article on their laptop that evening. Under a Blended identity with Google Signals enabled, GA4 can recognise that as one user. Under a Device-based identity, it counts as two. Neither is "wrong" — they answer slightly different questions — but switching between them shifts your numbers without any change in real behaviour.

The common misreading

People see their user count jump or dip after someone changes this setting and conclude that traffic itself moved. It didn't. Reporting identity is applied at query time, so changing it can restate historical figures too. Before you react to a sudden shift in users, check whether the reporting identity — or Google Signals — was recently changed. The behaviour is the same; only the counting method moved.