Rolling Retention allows you to grasp how many users have run your application at least once N days past the date of installation. Let’s say we’re calculating the 3 Day Rolling Retention of a certain date, which we call Day 0. We take the total number users who installed the application on Day 0, and we calculate the percentage of those users who activated your application at least once between Day 3 and today. This percentage is the 3 Day Rolling Retention. Similarly, to get 7 Day Rolling Retention, we calculate the percentage of users who activated your application at least once between Day 7 and today.
Since Rolling Retention is dependent on the date of calculation (today), it will be different every time you check it. For example, if you view the Rolling Retention metrics of January 1 on January 20, dates subject to analysis are 1/2 ‐ 1/19, while if you view them on January 30, the dates subject to analysis are 1/2 ‐ 1/29.
Retention is a snapshot. We calculate the percentage of users who ran your application exactly 1/3/7/14/30/60/90 days after the date of installation, with users who ran the application at least once as the denominator.