There has been plenty of emotions leading up to Google Analytics 4 or GA4 being released and the increased pressure to make sure we are each ready. I finally decided to try to make sense of Google Universal Analytics and GA4 and here were my key notes in case others find this helpful.

1. Dates – Universal Analytics (UA) deprecated July 2023 and UA 360 now deprecated October 2023.
   
2. Users – same term used in GA4 but it means active users instead of total users.
   
3. Model – UA is session-based (a session was a group of user interactions) where GA4 is an event-based model.
   
4. Engaged Session is the count of sessions that lasted longer than 10 seconds, or had a conversion event, or had two or more screen/page views. This will replace the pages per session metric.
   
5. Average Engagement Time Per Session is the amount of time the user is actually engaging with the page and is the page on the primary window being viewed on screen. This will replace the average session duration metric.
   
6. Engagement Rate is the ratio of engaged sessions relative to total sessions. This will replace the bounce rate metric although it can still be calculated as the inverse of the engagement rate. 100 total sessions with 15 of them being engaged sessions results in a 15% engagement rate.
   
7. Four Categories of Events
   a. Automatically collected events like user engagement, in-app purchases, and Firebase app interactions.
   b. Enhanced measurement events (change in user interface; no code changes required) like page views, scrolls, form interactions, and video engagements.
   c. Recommended events that have predefined names and parameters like online sales and user behavior.
   d. Custom events that you define and create when existing events don’t exist.
   
8. Segments – both in UA and GA4 you can compare up to four segments. Types of segments in GA4:
   a. User segments – subsets of users who engaged with your site/app like users from a page or channel.
   b. Event segments – subsets of events that were triggered on your site/app like purchase events.
   c. Session segments – subsets of the sessions that occurred on your site/app like a particular advertising campaign.
   
9. Segmentation Conditions tell analytics what data to include in or exclude from the segment. There are three segmentation conditions:
   a. Dimension conditions like demographics, geography, and technology.
   b. Event conditions about particular details on one or more events. This is new to GA4.
   c. Metric conditions based on predictive metrics like an in-app purchase probability is above the 90th percentile.
   
10. Attribution Modeling is assigning credit for conversions to different ads, clicks, and other factors. There are three types of attribution models available in the Attribution reports:
    a. Cross-channel rules-based model ignores direct traffic and attributes 100% of conversion value to the last channel that the customer clicked through or engaged view through for YouTube before converting. Other cross-channel rules-based models include:
    i. Cross-channel first click – all conversion credit to first channel that a customer clicked.
    ii. Cross-channel position based – attributes 40% credit to first and last interaction and remaining 20% credit distributed evenly to middle interactions.
    iii. Cross-channel linear – distributes credit for conversion equally across all channels a customer clicks.
    iv. Cross-channel time decay – gives more credit to touchpoints that happened closer to time of conversion. Uses a 7-day half life so a click 8 days before conversion gets half the credit of a click 1 day before a conversion.
    b. Ads-preferred rules-based model – attributes 100% conversion value to the last Google Ads channel that the customer clicked before converting. If there is no Google Ads click, attribution model falls back to cross-channel last click.
    c. Data driven attribution – uses machine learning algorithms to evaluate converting and non-converting paths. Distributes credit for the conversion based on your account data for each conversion event.
    
11. UTM parameters – there are two new UTM parameters in GA4. See https://support.google.com/analytics/answer/10917952?hl=en#zippyhttps://support.google.com/analytics/answer/10917952?hl=en#zippy for more details.