Building a cohort calendar for festival season
If your first-open window swallows both a year-end campaign and Songkran, your week-4 number is a collage. Collages are allowed in mood boards. They are unwelcome in a steering packet.
A utility app that sat Cohort Narrative for Stakeholders last winter had been rolling a single “Q4 new users” cohort from 1 October through mid-April. That window included year-end bill-pay spikes, Chinese New Year in some districts, and Songkran. Their retention looked volatile. It was mostly a calendar artefact.
We had them cut first-open into three named bands: post-rainy quiet weeks, year-end campaign, and Songkran fortnight. Week-4 engagement inside each band was dull in a useful way. The collage had been doing the drama. Finance stopped asking for a single “Q4 number” and started asking which band they were funding.
Rules we actually use
Name the window in the cohort spec, not only in a slide footnote. Keep festival fortnights as their own first-open bands even if sample size hurts. Do not “fix” small n by merging them back into the quiet band. A small honest cell is better than a large contaminated one.
Align engineering implementation with the named bands before you brief leadership. If the warehouse still uses a rolling 180-day new-user flag, the narrative will lie no matter how elegant the memo.
Where this sits in the studio
Engagement Benchmark Studio Module 02 is where leakage and windows get specified. Module 03 adds the Thai calendar. Cohort Narrative for Stakeholders is the two-day intensive for people who only need the memo skill. If your warehouse still cannot cut by named bands, start with engineering, not with another dashboard skin.