Hold beliefs that can lose, and let the data retire them.

Marketing rarely stops doing anything: channels and formats get added, almost nothing is retired, and keep-or-kill goes to whoever argues hardest. The Experiments discipline holds marketing beliefs in a form that can be defeated: written, with a prediction and a date. Every activity states what it must move, and by when, before it starts — written first, because after the results any outcome can be argued into a success. The artifact is a decision log: what you killed, what you kept, on what evidence. A team that has killed nothing this quarter has simply never put anything on trial. This is not A/B testing: button tests put trivial things on trial while the big bets run for years unexamined; the bigger the spend, the more it needs a written bar. Our own machine keeps its beliefs in a ledger with confidence levels and evidence classes — and its most important belief, that engineered distinctiveness causes a measurable lift in AI recommendation, is marked unproven, with the experiment that would settle it. Part of Growth Engineering; grade your stack with Stack Score.