19 January 2026 · Craft

Annotating retention without theatrics

Retention curves attract decoration. A red arrow labelled “iOS 18?” appeared in three packs we saw in a single month. None of the authors had checked whether the dip lined up with the store rollout in their own cohort. The arrow had become the claim.

Our annotation rule is dull on purpose. A vertical line with a date. A short noun phrase: “price test ended”, “BBC story”, “payday Friday”. No verbs that assign blame. No colour that is not already in the series. If you need a second colour, you probably need a second chart, which means the pack is no longer a retention story.

For consumer apps, we also forbid “wow” callouts on D1. Day-one movement is often instrumentation. Put the note in an appendix for the analyst, not in the exec one-pager. Executives in UK health and fintech apps have learned to distrust D1 theatre; they will trust a D7 sentence with a named confound.

If your tool only allows emoji markers, export. Teaching software to be quieter is not Iona’s job. Your job is the sentence that remains after the markers are gone.