Modeling conversion metrics

Turn a sequence of steps into a durable conversion model. Read modeling-warehouse-foundations first for the view-vs-dbt decision and the view-* workflow. Definitions: references/conversion-metric-definitions.md; recipes in references/posthog/ and references/dbt/.

The conversion model

A funnel is an ordered sequence of events/actions; conversion is the share of units that entered step 1 and reached a later step. Four parameters define it:

• Steps — the events in order (e.g. signed_up → activated → purchased).
• Conversion window — a hard time-box: a unit only counts as converted if it completes the steps within N seconds/days of entering. This is the parameter people most often forget to pin down.
• Aggregation unit — person_id (B2C) or a group key ($group_0, account — B2B). Decide once.
• Order mode — ordered (later steps after earlier, anything allowed in between), strict (no other event between steps), or any order.