Measure

Spell out the instrument and unit that turn your observable into a number: which data source, which event, counted how, in what units, per what thing. Anyone reading it should be able to produce the same number without asking you.

Spell out the instrument and unit that turn your observable into a number: which data source, which event, counted how, in what units, per what thing. Anyone reading it should be able to produce the same number without asking you.

Example

For activation you write: count of distinct calendar days with at least one sessionstart event in the product events table, per user account, days one through seven after signup. Not the marketing dashboard's login count, which double-counts mobile and web sessions.