Day 7 retention by cohort

Group users into cohorts by signup_date. For each cohort:

cohort_size is the number of users who signed up that day
retained is how many of them had at least one event exactly 7 days after signing up (signup on Mar 1 means an event on Mar 8)
retention_pct = 100 * retained / cohort_size, rounded to 1 decimal place

Every cohort must appear, including ones where nobody came back.

output columns

signup_datecohort_sizeretainedretention_pct

uses ,

ctrl + enter to run on the sample data · ctrl + shift + enter to submit

run your query to see the output here. Submit checks it against the sample data, hidden test cases, random data and a large dataset.