PJ / DEEPBRAINInterview decision lab
STUDY GUIDE · 23 OCT 2026
deepbrain.define-labs.com
Practice / PERSONAL STUDY · PUBLIC, SYNTHETIC & PROPOSED LABELS APPLY

THE MAIN POINT

Can the apparent variant difference support rollout?

0s

Uses your device's speech voices. No paid API. Test your speaking pace aloud.

E13 · Reject a bad experiment readout

Synthetic practice, not company performance.

One decision

Can the apparent variant difference support rollout?

Run the exact query

WITH b AS (SELECT * FROM v_user_cohort WHERE ('all'='all' OR persona='all') AND ('all'='all' OR primary_workflow='all') AND ('all'='all' OR substr(signup_at,1,7)='all') AND date(signup_at)>='2026-05-01' AND date(signup_at)<'2026-10-01') , acc AS(SELECT account_id,COUNT(*) eligible_seats,COUNT(DISTINCT variant) variants FROM b WHERE mature7=1 GROUP BY account_id) SELECT COUNT(*) mature_accounts,SUM(variants>1) mixed_variant_accounts,1.0*SUM(variants>1)/NULLIF(COUNT(*),0) interference_rate,SUM(eligible_seats) eligible_seats FROM acc;

Download SQL · Result CSV · Metabase saved question

Chart and reading

Synthetic practice chart

Q13 counts mature accounts with mixed seat assignments; inspect this interference before inference.

Challenge your recommendation

Are team members exposed to both variants?

Guardrails: This lab assigns users, so team accounts can have mixed variants. This audit is not a causal comparison; fix assignment before inference.

Next evidence: Account-level assignment and actual exposure, preregistered success and harm criteria.

PRD sections: 12, 14. Open proposed PRD

Your spoken decision

State one takeaway, one caveat and one action in 30 seconds. Then stop.

Connect this finding

What this chart helps decide · Follow the connected decision · Canonical metric definitions

Optional model answer — try your own first

E13 · Reject a bad experiment readout

Decision: Can the apparent variant difference support rollout?

Readout: Q13 counts mature accounts with mixed seat assignments; inspect this interference before inference.

Actual query output (synthetic), first rows:

mature_accounts mixed_variant_accounts interference_rate eligible_seats
167 35 0.20958083832335328 280

Model spoken answer: I would reject a causal conclusion here because seat assignment can mix variants inside a team account.

Caveat/counterargument: Are team members exposed to both variants? This lab assigns users, so team accounts can have mixed variants. This audit is not a causal comparison; fix assignment before inference.

Next evidence: Account-level assignment and actual exposure, preregistered success and harm criteria.

Deliberately left out: A ship recommendation based only on a favorable point estimate.

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Your practice notes

Write your answer first. Notes autosave locally; reading completion does not judge correctness.

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