Retention Segments is an engagement analysis feature, available with Enterprise Edition. It unrolls your users' session and event behavior starting from their very first session.
- You can select retention type that you're interested in.
- Here you select data type you want to use in calculation: session or event (views, crashes and feedback are listed under events). Session and event retention has a tiny but important difference (see day-0).
- You can select period and bucket. For the sake of simplicity, this document uses day terminology. Nonetheless, all examples and descriptions apply to weekly and monthly retention as well.
- You can target a specific set of Day-0 users/new users using query editor.
- Shows overview graph for selected time period. It basically depicts the ratio of (sum of n-th day/sum of day-0). That is, it summarizes tabular data in a single chart.
- Each row of the table denotes a day/week/month. "New users" column can be renamed to "users" when using event retention. Please see next sections for details.
- Scrolling part of the table shows corresponding ratios of retention (ratio of users retained on day 1, ratio of users retained on day 2, so on)
Day-0: Session retention vs. Event retention
Day-0 is a term to define the starting point of the retention. In session retention, Day-0 is obviously the first session or visit of the user. Retention calculation methods use that day to determine overall retention. It answers questions like “How many users who had their first session on April 3 (59 new users) had another session on day-5 (April 8, 5.08%) too?”
Event retention, on the other hand, has a fundamental difference compared to session retention. It doesn’t require an event to be done for the first time. It answers questions like “How many users who did Login on April 3 (87 users) did Login on day-5 (April 8, 9.2%) too?”
It is important to note that "like" is underlined in the examples. Answers of those example questions depends on the retention calculation method, that's why. Let's take a look at them.
Retention calculation method
There are 3 different types of calculation methods: full, classical and unbounded. Each type provides a different approach to crunch session/custom event numbers to calculate retention. Both session and event retention support all those three types. Following examples are given for session retention, but methods do not differ for event retention. That is, “Session” can be replaced with an arbitrary event name. That being said, it is important to remember the slight difference between session and event retention that is explained in the previous section.
Full retention is the most strict approach compared to others. Once the user skips a day, retention gets broken for her and is not changed after that point. The table below demonstrates a fully retained (3 days) user.
Classical retention doesn’t require continuous sessions/visits. Days are affecting only themselves, but not previous or following days. In other words, if a user has a session for a day, then she is considered retained on that day.
Unbounded retention is even more tolerant than Classical. All days between Day-0 and last session day is considered as retained no matter there are sessions before the last one.
More on technical details
Session/Custom event counting policy
In order to determine a day has session or custom event, we use absolute differences. For example,
- Let’s say first session is at Jan 1, 2018 22:00 (Day-0)
- Next session is at Jan 2, 2018 00:00 (Day-1)
- Only 2 hours passed but date is changed. So, it is counted as a day. We didn’t wait 24 hours to pass.
From the storage point of view, there is an upper limit for session retention values. Daily retention, for instance, is not stored if the time span starting from Day-0 is longer than 30 days.
- Daily retention: 30 days
- Weekly retention: 24 weeks
- Monthly retention: 13 months