Enumerated Failure Modes Are Realised More Often When Spoken Aloud: A Three-Arm Cluster-Randomised Trial of the Pre-Mortem Meeting, with a Sealed Written Control

In every family somebody says: don’t jinx it. They are right, and the risk-management profession has spent forty years doing it on an industrial scale. The pre-mortem meeting asks a delivery team to state aloud, in front of colleagues, every way the plan might fail, and treats the resulting register as a forecast. We randomised 1,148 projects across fourteen organisations to three arms matched on anticipation, on documentation and on meeting burden, and differing only in whether an enumerated failure mode was spoken and heard. Modes spoken aloud in the presence of listeners were realised within twelve months more often than modes written and sealed unread (hazard ratio 1.61, 95% CI 1.34 to 1.94). The hazard rose with the specificity of the wording, by 1.23 per grade on a five-point scale, and with the number of people who demonstrably heard it. Attendance, once audibility was conditioned upon, did nothing. Modes read aloud to an empty room behaved exactly like modes never spoken at all (1.02). Failures that no register had named were unaffected. We propose no mechanism, and we do not think one is required in order to stop. Enumerate in writing. Seal the register. Circulate it as a document and read it to nobody. A risk register is an order form.