Why cohort matters to a first-time founder
Without cohorts, a wave of new sign-ups can hide the fact that last month’s customers are leaving. Overall numbers mix old and new customers, so a growing total can mask a product that keeps nobody. Comparing groups by start month shows whether retention is improving as you change onboarding, pricing or the product, and tells you which change helped and which one broke something.
Examples of cohort
The twenty freelancers who started in March are one cohort. In June, twelve of them still pay. That 60% is about March, not about the company as a whole. April’s cohort might look worse. A single churn rate for the whole spring blends the two and hides which month you broke something.
Common misunderstanding
People think of a cohort as any segment, such as “designers”. A segment shares a trait. A cohort shares a start. They also look only at the newest group, because it is the largest, and ignore the older groups that already answered the retention question.
When to use it
Start once you have two or three start months to compare. If every customer arrived in the same fortnight, you have one cohort and the chart cannot show a trend yet. After that, compare cohorts each month and use the difference to decide which onboarding or pricing change to keep and which to roll back. Be wary of reading much into very small groups.