This article will help you:
In a retention analysis, the usage interval shows the percentage of active users who’ve triggered the selected events with a specified daily, weekly, or monthly median frequency. These events must be triggered on at least two different days in order for the users to be included.
Your usage interval is important for drawing accurate conclusions about your retention numbers. Some products are built to be used daily, while others might be used much less frequently. Knowing how often your product is actually used will help you gauge the health of your product when looking at Retention Analysis and Lifecycle charts.
To view the usage interval, click Usage Interval in the Measured As module.
Let's say your product's critical event is
Purchase Song or Video. You can select this event and use the usage interval view to find the usage interval for that event. To calculate this, Amplitude plots the distribution of each user's median return period: For each user, Amplitude will look at all
Purchase Song or Video events they triggered in the last 15 days, and then determine the median length of time between each of these events.
For example, the highlighted data point tells us that 65.4% of your users have a median interval of four days or fewer between each
Purchase Song or Video event. This inflection point can be interpreted as your usage interval. You can use this usage interval to create a Return On (Custom) chart or a Lifecycle chart. In this case, it looks like four days is the expected usage interval for active users with the critical event of
Purchase Song or Video.
NOTE: To learn more about how to find your critical event, check out this blog post or our Product Analytics Playbook Vol. 1: Mastering Retention.
You can see how the median frequency between events changes over time by selecting the Usage Interval Over Time view. Amplitude does not plot averages in this view; instead, it shows the actual percentages.
For example, the following data point shows us that of the users who triggered
Purchase Song or Video on March 10th, 89.1% of them fired it again within seven days.