Instead of looking at cumulative vanity metrics over time, the more accurate analysis is to separate users into groups based on the time they joined, then measure your metric for each group independently. Each group of users is called a cohort.
Cohort Analysis in Lean Startup – Easy Guide
![Cohort Analysis in Lean Startup – Easy Guide Cohort Analysis in Lean Startup – Easy Guide](https://www.allencheng.com/wp-content/uploads/2019/07/leanstartup-kpis-678x350.jpg)