💼 Cohort

Cohort#

A group of users sharing a common start characteristic, tracked over time.

Important

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What it is#

A cohort is a group of individuals who share a common characteristic within a defined time period. Across statistics, business, healthcare and ML, cohorts let you study patterns within one group over time rather than blurring everyone together — the idea is to track the journey of a group that has something in common.

Kinds of cohort#

The shared trait varies. A signup cohort is everyone who joined in January 2024; an acquisition cohort is everyone won through a Q1 ad campaign; a behavioural cohort is those who purchased within their first week. The same idea drives a medical cohort (patients diagnosed in 2022) and an education cohort (the Fall 2020 entering class).

Cohort analysis#

Cohort analysis tracks a metric for each cohort over time. A retention table, for instance, follows monthly signup cohorts down the rows and elapsed months across the columns — a January cohort might retain 70% at month 1, 50% at month 2, 35% at month 3 — revealing whether later cohorts behave differently from earlier ones. It removes noise by comparing groups with shared starting points, and it controls for time-based effects like seasonality.

Cohort vs segment#

The distinction is time. A cohort is defined by a shared event in a time window (“everyone who joined in March”); a segment is defined by attributes regardless of when (“all users aged 18-24”). Cohorts answer “how does this group evolve?”; segments answer “who are these people?”.

Theme: Business & Growth Analytics · All terminology

Hint

Mind map — connected ideas

Customer Segmentation · Retention · Churn · Causal Inference · Revenue per User (RPU / ARPU)

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More in Business & Growth Analytics

Blended CAC (Customer Acquisition Cost) · CAC (Customer Acquisition Cost) · Cannibalization · Channel-Specific CAC (Customer Acquisition Cost) · Churn · Cohort-Based LTV (Simple Version) · Conversion Rate (CR) · Cost-Per-Click (CPC) Models · Cross-Selling · CTR (Click-Through Rate) · Customer Lifetime · Customer Segmentation · D2C (Direct-to-Consumer) · FTEs