Cohort Analysis Q1 vs Q2 | Dataford Interview Questions

The Starlink customer portal team wants to compare early engagement for users who signed up during Q1 and Q2 of 2025. Write a PostgreSQL query that produces a three-month retention view for each signup cohort.

Requirements

Include only users who signed up from January 1 through June 30, 2025, and label them Q1 or Q2.
For month offsets 0, 1, and 2 after signup, count distinct users with at least one session_started event during that month.
Return cohort size, active users, and retention percentage, ordered by cohort and month offset.

Schema

users

Column	Type	Description
user_idPK	INTEGER	Unique Starlink customer portal user identifier
signup_date	DATE	Date the user created an account
email	VARCHAR(255)	User email address

product_events

Column	Type	Description
event_idPK	INTEGER	Unique product event identifier
user_id	INTEGER	User associated with the event
event_timestamp	TIMESTAMP	Timestamp when the event occurred
event_type	VARCHAR(50)	Name of the recorded product event

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