Pre-mortem
Also known as: prospective hindsight, premortem.
A planning exercise: imagine the project has already failed and write down why, before starting. Treating failure as certain makes people name risks they would otherwise keep quiet about.
Synthetic dataExamples on this page use synthetic data created for illustration.
Not adviceThis is educational material. It is not investment, business or other professional advice.
Definition
A pre-mortem is a planning exercise in which a team imagines that the project has already failed and writes down why, before it starts. Imagining the failure as certain makes people name risks they would otherwise stay silent about, and the best of them become actions.
In plain terms
Gary Klein popularised the method, building on research showing that people explain a future event better when they picture it as having already happened (“prospective hindsight”). Teams in love with a plan tend to suppress doubts; the exercise gives doubt a job.
A typical run: state the plan; announce “it is a year from now and the plan failed badly”; each person writes the reasons, silently and on their own; the reasons are collected and ranked; the most serious become concrete safeguards, early-warning signs or decision triggers, and go into the Decision Record.
Example
Plan: run a weekly screen that flags items whose ratings are rising fast.
| Imagined cause of failure | Early-warning sign | Safeguard decided |
|---|---|---|
| The source changes its page layout and a field silently goes empty | Share of items with a rating count drops | Alarm on field fill-rate; keep the raw pages |
| Items that leave the list are dropped, so only survivors are studied | Number of tracked items shrinks | Keep exited items, with the reason (Attrition Bias) |
| We tuned the thresholds on the same data we judged them on | Results too good to be true | Freeze a holdout before tuning (Holdout Set) |
Each safeguard exists because someone was allowed to say, in advance, how it would go wrong.
Common misunderstandings
- “A pre-mortem is just pessimism.” It is structured, time-boxed and ends in actions, not in a mood.
- “We already have a risk register.” A register lists risks people are comfortable naming; the exercise surfaces the ones they are not.
- “It is for large projects only.” It takes half an hour and suits a small analysis as well.
References
- Gary Klein. Performing a Project Premortem . Harvard Business Review, 2007.
- Deborah J. Mitchell, J. Edward Russo, Nancy Pennington. Back to the Future: Temporal Perspective in the Explanation of Events . Journal of Behavioral Decision Making, 1989. DOI: 10.1002/bdm.3960020103