Reference

Data.

A short reminder. Follow a lesson for the decision behind the term.

KPI

A metric selected to track progress toward an important objective.

Why a PM cares: It should have a clear definition and influence a real decision.

A chosen shared measure intended to represent recurring product value.

Why a PM cares: It can align investment but needs guardrails and evidence that the proxy remains useful.

A defined sequence of user actions measured for an eligible population and time window.

Why a PM cares: It helps locate loss in a journey before choosing an intervention.

An early behavior that plausibly indicates a user or account has experienced value.

Why a PM cares: Setup completion alone is not enough; validate the relationship to later success.

A group sharing a defined starting event or characteristic.

Why a PM cares: Comparing groups at the same age helps separate acquisition growth from retention quality.

Repeat activity by a defined population after a defined interval.

Why a PM cares: The return event, cadence, and denominator determine what the number means.

The system of events and properties used to record product behavior.

Why a PM cares: Incorrect events can imitate a product improvement or conceal a failure.

A distortion caused by who is included in or excluded from the observed data.

Why a PM cares: Feedback from active users may omit the people whose problems caused them to leave.

A controlled comparison using assignment to different experiences.

Why a PM cares: Valid design and measurement help estimate effects, but uncertainty and interference still matter.