Retention Weather exists because too many United Kingdom product reviews still open with a single percentage, printed large, compared with last quarter. The room relaxes or panics. Almost nobody asks which Tuesday’s installs are in the blend, or whether “active” still means the same job after the onboarding rewrite.
Think of fronts. People who arrived from a paid story, people who denied a permission, people who completed one job on day zero — these are different skies. Averaging them is like averaging Glasgow and Lisbon and calling it “the British climate”.
What we mark
Students draw at least two curves and write a sentence about the gap. If they cannot, the instrumentation is not ready for a retention claim. We would rather send you back to the dictionary than watch you decorate a blended line.
A mild reservation from the last cohort: this language irritates finance partners who need one number for a model. Give them a number, labelled as a model input, and keep the weather for product. Do not launder the model input into a story about love for the app.
Day N is a convention
N equals 7 because slides are square, not because your users think in weeks. A health tracker might care about the second workout, whenever it happens. A B2B inbox might care about the second teammate invited. Name the job. Then the curve has a meaning.