Understanding Sessions in GA4 [2022]

Insight

To prepare brands for the major transition from Universal Analytics to Google Analytics 4 (GA4), we’ve written guides to help them through the process, including a complete GA4 setup guide.

In this piece, we’ll be covering another fundamental change: how sessions are changing in GA4, and we’ll explain the impact the new definition will have on your data reporting. 

How are sessions in GA4 changing?

In Universal Analytics, a new sessions starts either when: 

  • A user first lands on your site
  • A user lands on your site from a new traffic or source/medium campaign combination 

In both cases, a session ends after 30 minutes of inactivity. 

In GA4, however, a session has been simplified, to only include option 1: when a user first lands on your site. Session endings are the same in GA4, and they end after 30 minutes of inactivity. 

While this change makes sessions as a metric easier to understand, it has fairly significant consequences on your data and reporting, especially when users visit your site through multiple sources in a short period of time. 

An illustrative example of how your reporting will change

Let’s say Customer X has the following journey to make a purchase on your site:

  • At 12:00pm, they search “work jeans” on Google. They see one of your ads show up at the top of the SERP, click on the ad, and land on your website.
  • At 12:06, after they’ve browsed your site for several minutes, they return to the SERP and explore what some other brands have to offer. 
  • At 12:21, after spending some time looking through other brands’ products, they decide they prefer your offerings. They go back to Google, search for your brand name, and click on your organic SERP listing to get back to your site. 
  • At 12:22, after browsing your site for a minute, they find exactly what they’re looking for, they add the product to their cart, and they start to check out. 
  • At 12:24, they decide to search RetailMeNot for a promotion coupon on your site.
  • At 12:25, they find a promotion coupon on RetailMeNot and click on a link to get back to your site.
  • At 12:27, they complete their purchase on your site. 

Now, in Universal Analytics, this customer journey would be reported as 3 separate sessions:
       1. A session initiated by clicking on your paid ad at 12:00
       2. A session initiated by clicking on your organic listing in the SERP at 12:21
       3. A session initiated by clicking back to your site from RetailMeNot

However, in GA4, these 3 sessions would only show up as 1 session, initiated by their click on one of your ads at 12:00. Because the other clicks to your site occurred without 30 minutes of activity between them, GA4 will not break the journey into separate sessions. 

What does this mean for you?

In short, you can expect changes to your data. However, actual changes may vary considerably depending on how customers interact with your site. 

In general, though, you can expect three changes:

  • Overall sessions count will probably be lower
  • Session counts per source will look different between Universal Analytics and GA4. If you get a lot of traffic from affiliates that occur when a customer does a check for promo codes during checkout, you’ll likely see fewer sessions from that traffic in GA4 than in Universal Analytics. 
  • If you have abandoned cart emails that are triggered immediately after a customer leaves your site, you’ll probably see a lower session count there as well. 

Final point: why you may see a higher portion of traffic attributed to Direct in GA4

When you set up a new GA4 property, you’re likely going to see more traffic attributed to Direct than in your Universal Analytics property.

The reason? Google has a longer history of interactions with your Universal Analytics property to draw on when recategorizing the traffic to your site. 

Google needs more time to learn about your property in GA4 to properly categorize traffic. Universal Analytics attributes conversions to the last non-direct click, but it also attributes traffic to the last non-direct click. 

In Universal Analytics right now, a significant amount of your traffic that is associated with a non-direct source is actually direct. To check this, go to your Source/Medium report in Universal Analytics and add Direct Session as a secondary dimension: Acquisition > All Traffic > Source/Medium:

source/medium in GA4 with Direct Session

All the Direct Session rows that have Yes for this dimension are traffic that is not truly direct but is being associated with the last marketing source that the user interacted with.

So, if you’ve set up GA4 recently, it will have significantly less history to draw from when it comes to appropriately learning how to categorize traffic. It’s also not clear whether GA4 is attributing sessions to the last non-direct click.

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