Universal Analytics has officially been shut down since July 2023. All UA properties stopped collecting data. If you work with clients who still talk about "their Google stats", they now mean GA4: whether they know it or not.
But GA4 doesn't work like UA. Metrics have changed, reports have changed, and even the counting logic is different. The result: some numbers seem "wrong" or inconsistent compared to what the client had before. Here are the 7 differences you need to understand.
1. The data model: events vs page views
Universal Analytics was built on hits: page view, event, transaction. The session was the central unit.
GA4 is a 100% event-driven model. A page view is an event (page_view). A click is an event. A transaction is an event. The session still exists, but it's just a grouping of events.
This change lets GA4 track much richer behaviour automatically: scroll, embedded YouTube videos, file downloads, without extra configuration.
2. Engagement rate vs bounce rate
This is the difference that confuses clients most during the transition.
UA: bounce rate = percentage of sessions with a single interaction. A visitor reading an article for 8 minutes without clicking = a bounce. The metric was often misleading.
GA4: engagement rate = percentage of sessions longer than 10 seconds, OR with at least 2 page views, OR with a conversion event. It's the inverse of the bounce rate (non-engagement rate).
Your "70% UA bounce rate" can become a "60% GA4 engagement rate": visitors haven't changed, the measurement is better. Be careful when comparing the two periods in a client report.
3. Data retention
UA: data kept indefinitely (for properties created before the shutdown).
GA4: 14 months by default. Change it immediately in Admin > Data collection and modification > Data retention > 50 months.
If a client asks for stats from 2 years ago and this setting has never been changed, the data may be gone. It's one of the first things to check on every new GA4 property.
4. Unique users vs active users
UA counted unique users: anyone who triggered at least one session.
GA4 counts active users: people with at least one engagement (duration > 10 seconds, conversion event, or 2 page views). Ghost visitors who arrive and leave immediately don't count.
Result: the GA4 user count is often slightly lower than UA, even at equivalent traffic. It's not lost traffic: it's a more accurate measurement.
5. Multi-stream properties
UA: one property = one site or one app. To track web + mobile app, you needed two separate properties.
GA4: one property can have multiple data streams (web, iOS, Android). You track the same user across the site and the app in a unified view, with a common identifier if the user is logged in.
For clients with site + app, this is a major advantage of GA4.
6. Conversions: goals vs events
UA: conversions (goals) were configured manually with precise criteria (destination URL, duration, event).
GA4: any event can be marked as a conversion with one click in the interface. GA4 automatically detects certain key events (purchase, sign_up, generate_lead) if tracking is properly configured.
7. Default attribution
UA: last click attribution by default: the last channel before conversion got all the credit.
GA4: data-driven attribution by default on properties with enough data, otherwise cross-channel last click. Models are configurable in Settings > Attribution.
Consequence: channel numbers (Organic, Paid, Social) may differ between UA and GA4 even for the exact same period. That's normal.
A mapping table for your client reports
| UA concept | GA4 equivalent | What changes |
|---|---|---|
| Bounce rate | Non-engagement rate | Inverted calculation, more accurate |
| Sessions | Sessions (+ engaged sessions) | GA4 distinguishes both |
| Unique users | Active users | GA4 doesn't count visitors without engagement |
| Goals | Conversions (events) | One-click activation, more flexible |
| Page view | Event page_view | Same thing, new model |
Summary
- GA4 is fully event-driven: more flexible, more precise than UA
- Engagement rate replaces bounce rate (and it's better for everyone)
- Set data retention to 50 months immediately on every property
- GA4 active users < UA unique users: normal, not lost traffic
- Data-driven attribution can shift channel numbers vs UA
To generate clear GA4 reports for your clients without getting lost in these differences, NarratIQ extracts the metrics that matter and formats them into a PDF your client understands without knowing GA4.