Defining Revenue Cohorts

A cohort is a group of customers who share a common characteristic at a specific point in time — typically their acquisition month, but also their segment, channel, product tier, or deal size. The purpose of cohort analysis is to isolate behavior: how does the January 2025 cohort retain compared to the July 2025 cohort? If the aggregate retention rate is 92%, but recent cohorts are retaining at 84% while legacy cohorts retain at 97%, you have a problem the aggregate number is concealing.

1. Time-Based Cohorts Group customers by acquisition month or quarter. Track their revenue at consistent age intervals: month 3, month 6, month 12, month 24. This reveals whether your product-market fit is stable, improving, or degrading over time. The most dangerous pattern is a declining retention curve in recent cohorts — it means each new customer is worth less than the previous one.
2. Segment-Based Cohorts Group customers by segment: enterprise, mid-market, SMB. Each segment has different retention dynamics, expansion patterns, and support costs. Blending them into one retention number is like averaging the temperature of a hospital — technically accurate, completely useless for diagnosis.
3. Channel-Based Cohorts Group customers by acquisition channel: inbound, outbound, partner, event. Channel-specific retention reveals whether certain acquisition methods produce lower-quality customers. If outbound customers churn at 2x the rate of inbound customers, the outbound CAC is actually higher than it appears — because you have to replace them sooner.