[UA→GA4] How to increase confidence in your GA4 key event data

Google Analytics 4 (GA4) is the latest version of Google's analytics platform. It replaced Universal Analytics (UA) starting July 1, 2023, when the standard Universal Analytics properties stopped processing data (July 1, 2024 for UA 360 properties). It's critical that you migrate your UA property to Google Analytics 4. Learn how to get started.

When migrating to GA4, you may notice discrepancies between your UA key events data. This article explains the main differences in essential metrics between GA4 and UA, why these key event discrepancies occur, and tips on how to minimize them.

Before you begin

If you haven't yet replaced your UA conversion with GA4 key events in Google Ads, follow these steps to replace them with GA4 key events. Not updating your key event settings may disrupt your campaigns and affect your campaign's performance. To facilitate this transition, we recommend that you take the following actions:

• First, import your GA4 key events into Google Ads. If you still have active UA conversions recording events, ensure the imported GA4 key events are marked as “secondary” key event actions to avoid double counting.
• Next, compare your GA4 key events with the equivalent UA conversions that they’ll replace. You should do this in Google Analytics and Google Ads. Confirm that the GA4 key event count is as close as possible to your UA conversions. If your UA conversions are no longer recording events, you may need to look at historic data to complete this step.
• Finally, set your GA4 key events to “primary” in Google Ads.

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Sources of discrepancy

There are important differences between UA and GA4 that may make it difficult to compare your data and key events. These are the main reasons for discrepancy:

• Inherent differences between UA and GA4:

GA4 properties have a different data model than UA properties. GA4 collects events instead of hits, and uses AI-powered solutions, like behavioral and key event modeling to support new privacy-preserving technologies. These solutions give you a complete view of performance without compromising user privacy, but they're not available in UA properties.

Learn more about the Difference between UA and GA4.

• Differences in setup and settings:

UA vs. GA4 tag coverage, tag firing conditions, key event count, filters, URL parameter exclusions can all affect key events.

Learn how to Fix differences in set up and settings.

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Next steps

After you have set up data collection for your websites and apps you can:

• Fix differences in set up and settings
• Complete additional configurations to get more accurate and useful data.