Migrating measurement from Universal Analytics to GA4

GA4 uses an event and parameter model that does not reproduce Universal Analytics sessions, categories and actions directly. The migration should begin with decisions the organisation needs to make, not a mechanical copy of every existing tag.

Inventory decisions and current reports

List the reports, audiences and alerts that have an active owner. Identify the business question, calculation and downstream export behind each one, then retire dashboards that nobody can connect to a decision.

Design a controlled event model

Define event names, required parameters, user properties and allowed values in a versioned measurement plan. Prefer recommended GA4 events where semantics match, and avoid encoding changing content or personal data into event names.

Implement consent and data boundaries

Apply the organisation’s consent position before analytics initialises, review advertising signals separately from service measurement and prevent email addresses, order references and free text entering parameters or page locations.

Validate at collection and reporting layers

Use debug tools to inspect emitted events, then confirm that parameters, conversions, channel attribution and filters appear correctly after processing. Test duplicate tags, single-page navigation and cross-domain journeys with real consent states.

Preserve historical comparability

Export the Universal Analytics reports needed for trend and regulatory retention before access changes. Document metric differences and establish a parallel baseline; do not join UA and GA4 sessions into a continuous series without qualification.