What is unassigned traffic in Google Analytics?

In Google Analytics 4 (GA4), 'unassigned traffic' is a term used to describe website traffic that isn't linked to any specific channel group, such as organic search, paid search, referral, or direct. This happens when Google's predefined channel rules can't categorize certain types of traffic sources.

Google uses these channel rules to group similar website traffic sources that share the same traffic medium. For example, traffic sources like Google, Yahoo, Bing, and AOL, all having the 'organic' traffic medium, are collectively placed under the 'organic search' channel group. However, when traffic sources are user-defined or not set, Google lacks predefined channel rules to classify them, leading to their classification under the 'unassigned' channel group.

Spotting Unassigned Traffic in GA4

To check unassigned traffic in GA4, you need to go to the Acquisition Overview report in your GA4 property and scroll down to the data cards related to user acquisition and session acquisition. Here, you will find the unassigned channel group. This unassigned group can also be found in the User Acquisition report and the Traffic Acquisition report.

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Fixing Unassigned Traffic in GA4

To rectify the issue of unassigned traffic in GA4, you can follow these strategies:

1. Always use UTMs: This assists GA4 in precisely identifying the source, medium, and campaign information for each user, thereby reducing the likelihood of unassigned traffic.
2. Enable auto-tagging: If you're connecting your GA4 property to Google Ads, make sure to use auto-tagging over manual tagging as it provides more dimensions.
3. Familiarize yourself with channel rules and definitions for accurate tagging: Understanding how Google clusters similar traffic sources and defines a particular marketing channel can assist in tagging URLs that comply with GA4 default channel rules. You can read more about the default channel grouping and how it works.
4. Ensure that the source and medium information is not lost due to technical glitches: Some redirects can remove UTM parameters, causing GA4 to lose the source, medium, and campaign information. Also, ad blockers and other privacy settings can cause GA4 to lose this information.
5. Address issues with the “session_start” event: In GA4, when a new session commences, the 'session_start' event is activated. If this event is not sent or recorded, GA4 may not be able to associate the UTM parameters with the visit.