1 min lesson
Data drill
Use "Data drill" to explain each part and the role it plays.
Step 1 of 2
The data round hands you a schema and one question: "What's our stage conversion by segment?" The trap is that the obvious query double-counts. This drill is about getting the grain right, handling nulls on purpose and being honest about what your number does not capture.
Assume a typical GTM warehouse shape: a leads table (one row per captured lead, with segment, score, created_at) and a stage_events table (one row each time a lead enters a funnel stage). Set a 25-minute clock and narrate every definition as you write it.
The schema you're querying
- leads
- lead_id, person_email, account_domain, segment, score, created_at - but emails are not yet deduped.
- stage_events
- event_id, lead_id, stage ('captured'|'qualified'|'meeting'|'won'), entered_at.
- Gotcha 1
- Same person captured twice (two lead_ids) inflates every stage if you don't dedup to a person.
- Gotcha 2
- A lead can re-enter a stage; raw event counts overstate progression.
- Gotcha 3
- segment is NULL for self-serve signups that skipped the form.