blog · May 23, 2026

What is cohort analysis in ecommerce?

Cohort analysis groups customers by acquisition month and tracks their behavior over time — the only honest way to read retention, LTV, and the impact of changes you've made.

What a cohort is

A cohort = a group of customers acquired in the same time window (typically a month). You track that cohort's behavior across subsequent months independently from other cohorts.

Why it matters

Average metrics (overall retention, overall LTV) blend new and old customers — they hide trends. A cohort chart shows whether your month-3 retention is improving, getting worse, or flat over time — the only honest read of whether what you're shipping is working.

The patterns to look for

(1) Recent cohorts retain better than older ones → product/onboarding improvements are landing. (2) Recent cohorts retain worse → quality/onboarding has regressed. (3) Retention decay flattens after month 3 → you've identified your loyal-customer baseline. The shape of the decay is more useful than the absolute numbers.

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