So I activated Google Analytics 4 for my site and I’m running UA and GA 4 implementations in parallel [This is highly recommended from all major sites as GA 4 is still in beta]. Having recently done this, I thought about comparing some metrics from both implementations to check for any differences and sure enough, the Users metric didn’t match between both implementations.

For the last 7 days period combined, GA 4 shows 455 users while Google Analytics profile shows 463 users. Comparing the daily counts between both implementations, there’s a small variation between both of them. This led to me a rabbit hole of Google searches, which I’ll try to explain:

Presuming a certain level of familiarity with GA 4, you also understand that the point of GA 4 is to unify measurement reporting across… App plus Web properties. In a traditional sense, browser cookies has been used to identify unique users while User-ID reporting can unify experiences across multiple browsers. With GA 4, this User-ID feature now extends to including apps as well. If a User-ID field is available, it can be used to identify users. Without User-ID, GA 4 falls back on browser cookie tracking for web activity, same as Universal Analytics.

Ok, so where do the differences come in?

1. GA App plus Web automatically removes bot traffic by default [no option to un-check this]. There are also no options for Views in GA 4 so far. In UA, View Settings has the box checked for block spam/bot traffic but it can unchecked. In comparing my two implementations, I have now created a separate view with just one setting - block spam/bot traffic. I will then update this post later to see if User counts get closer to UA implementation. For now, the closest comparison I had for GA 4 vs UA was my unfiltered profile. Let’s see how this goes in a week.

2. GA 4 does not support filters yet. IF your UA has filters, it won’t be a fair comparison.

3. App + Web Properties focus on active users (users who are currently engaged), while Standard/360 properties focus on total users. This differentiation was crucial for me and the key is in the language. What does this mean “active users (users who are currently engaged”? In a traditional sense, UA would count a user on landing but App plus Web is looking at engaged users? Since GA App plus Web is essentially Firebase [for mobile] being extended to include Web, I thought of checking Firebase documentation to understand what’s an engaged user? Based on here, an active user has engaged with an app in the device foreground, and has logged a userengagement event. Ok, so in a traditional website environment, would that mean that the website is the active tab AND user_engagement event has fired? Next question: When does user_engagement event fire in Firebase? This question led me Stackoverflow thread with he short answer being user has engaged for at least 10 sec. The thread references to a setMinimumSessionDuration() call. However, when I checked Firebase documentation again for this call, it now shows that setMinimumSessionDuration() call has been deprecated.

Ok, so I don’t have the answer to user_engagement part right now. I’ll be tweeting this out to Google Analytics to find out an answer and see if the #measure community can also help.