Change over time
Retention curve
- Change over time
What it shows
What share of a cohort is still active after each period.
When to use it
Use a retention curve to show the proportion of an initial cohort still meeting an activity definition after each elapsed period.
Worked example
If 100 people sign up, 68 return in week one and 41 in week four, retention is 100%, 68% and 41% at those checkpoints under the stated definition.
Data required
Start event, cohort size, consistent return criterion, elapsed periods and handling of incomplete follow-up.
Checks and common mistakes
Avoid mixing users with different exposure windows. Distinguish point-in-time retention from rolling retention and show sample sizes.
More accessible alternative
Provide an exact-value table and cohort heatmap when several acquisition groups must be compared.