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I need some help trying to understand what seems to be very weird numbers on user engagement for firebase analytics.

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The above picture says that the daily user engagement is 35 seconds, however, looking at the "Top Screens/Pages" I can see average times of a least one minutes, and if I go into the page_view event details for the same period, I can see very big numbers, for example, a 13 minutes average time for a page with a total of 17%.

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So, how can the daily user engagement be only 35 seconds? Additionally, what is the "% total" referring to?

BernalCarlos
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2 Answers2

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Daily User Engagement does not show the average session duration but the average of the sum of all the session durations.

This means that it represents the average time your users engage with your app in the foreground, but not necessarily during a single session.

dmuensterer
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  • To help me understand your definition of daily user engagement better, if there are 5 sessions in a day say [30, 45, 27, 5, 12] in seconds. Average session duration would be 30+45+27+5+12 = 119 / 5 = 23.8 seconds ? And what would be `average of the sum of all the session durations` ? – Siddhesh T Jun 22 '20 at 16:39
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By hovering on the '?' next to Daily User Engagement, you can see the following definition:

Shows average daily engagement with a graph displaying trends for the time range selected. Move your mouse over the graph to show average engagement for a specific date.

The top screens chart shows the name of the screen class, the percentage that screen accounts for in engagement time, and the average amount of time that screen was used for the time range selected.

Let me walk you through the first part with the screenshot you have shared.

  • In your screenshot the time range selected is missing, so I am assuming that the time range selected is the default 28 days. The 35 seconds is the average of the daily average engagement per user of the selected period. The 28.1% means it is down by that percent compared to the previous period of 28 days. If you change the time range, it will show the number for the current 7-day period vs the previous 7-day period. Or 1-day vs the previous-day average engagement.
  • If you hover on the graph below these numbers, it will show you the average engagement for the specific day.

Next coming to the Top Screens/Pages below the graph, we can refer to the second point which says, this table will show you the list of top-performing screens/pages. Against each page, there is % total and Avg time.

  • % total refers to the percentage that screen accounts for in engagement time, say if the total engagement time for the selected period of 28 days for your whole app comes to 100 mins (total engagement time, not the average for the day), and if a particular page /page1 had contributed a total of 17 mins, then the % total will show 17% as this page's % share in the total engagement time.
  • Avg time refers to the average engagement time for the page for the selected period, assume 28 days here. (This as well, should be across all users, similar to % total)

Both of the above points stand true for the next screenshot you have shared as well.

Let me ask you a question: What is the average for [26, 0]? 13 right? And what is the average of [26, 0, 0, 0]? 6.5 right? It is a few simple math calculations to figure how you may be having 13 mins for average engagement for a page even though the page only contributed 17% to the total engagement time for the selected period. As you will also understand from the last link in this answer, firebase analytics calculates the user engagement and session start/stop in a very specific way and it can affect the Daily User Engagement number in a really interesting way.

Daily User Engagement: Average daily engagement per user for the date range Firebase Help

A 35 second of avg daily engagement for 28 days would translate to 28*35 = 980 seconds ~ 16 mins engagement per user in 28 days. Since we don't know the number of users, we can't reach the total engagement time for the 28-day period. Some users may have spent a few seconds and some users may have spent almost an hour, to reach an average of 16 mins.

I hope you understand what I am trying to explain here. You will have to deep dive into the raw data and understand even better how it came to be 35 seconds.

I have tried to be as simple as possible, but if you would want to know more there are a few interesting Q&A on SO which you could refer to:

Siddhesh T
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  • Thanks @Siddhesh fo the detailed explanation. It makes sense. – BernalCarlos Jun 22 '20 at 17:32
  • Just one more thing, what happens is a user opens up the page in a chrome tab, and keeps it open for a long time, not even doing anything? He is just opening more tabs while browsing the web. – BernalCarlos Jun 22 '20 at 17:35
  • It could cause a long user session if it goes out of focus, as I can understand from this answer https://stackoverflow.com/a/48689408/3070768 a session ends after at least 30 minutes of no triggers of user_engagement. If the concern is about how it affects the user_engagement, it could I think. All in all, it is a good to know metric but not the best one in terms of accuracy. There are a bit of flaws to it. – Siddhesh T Jun 22 '20 at 18:56