Churn

The rate at which customers quietly leave. It measures disappointment better than any survey.

Churn is disappointment with a timestamp. Surveys collect what people say; departure records what they concluded. The number is merciless because leaving costs effort, so every percentage point represents people for whom staying became worth less than the trouble of going.

Read it forensically, by cohort and by moment: leaving after the first week indicts onboarding; after a price change, the value story; after two years of quiet, neglect. Exit notes, when people leave one, are the cheapest research a company will ever receive, and the least read.