Choosing the Right Scope for Your Data (Custom Dimensions)

Why this matters

GA4 distinguishes between built-in properties (collected automatically), event-scoped custom dimensions (attached to a single event), and user-scoped custom dimensions (attached to the user forever), and choosing the wrong scope causes data to vanish from reports or inflate incorrectly.

Try it yourself

1. In GA4 Admin > Custom Definitions, create one event-scoped custom dimension called plan_type mapped to the plan_type event parameter, then trigger an event carrying that parameter and verify it surfaces in Explore within 24 hours (or use DebugView for immediate confirmation).
2. Compare the cardinality of page_location (a built-in property) versus a custom dimension you've registered by checking the 'Row count' in a free-form Exploration — confirm the built-in never hits the row limit.
3. Delete a registered custom dimension and observe what happens to historical data in reports — note whether past rows are retroactively removed or preserved.

References

• https://support.google.com/analytics/answer/10075209