Core idea: A premortem asks participants to imagine that a chosen plan has clearly failed in the future and explain why.
When this model is useful
Use it before commitment to surface concerns that optimism, hierarchy or momentum may suppress.
The method is most useful when the question, alternatives and time horizon are stated before calculations begin. It should clarify tradeoffs and identify which assumptions deserve attention, not merely produce a score.
Inputs and evidence
A proposed option, a future failure date, independent participant observations, likelihood, consequence, detectability and possible controls.
Use consistent units, definitions and periods across options. Mark estimates clearly, record their source and use ranges when precision is not supported. Evidence should be proportionate to the cost, risk and reversibility of the choice.
Step-by-step method
Collect failure causes silently, group them, prioritize plausible high-consequence items, and assign tests, controls, owners or stop rules.
- Write the decision question and accountable owner.
- List realistic alternatives and eliminate any that fail hard constraints.
- Collect evidence and separate verified facts from assumptions.
- Run a base case and at least one downside test.
- Record the chosen option, accepted tradeoffs and review triggers.
Practical example
A technology rollout premortem may reveal adoption failure, integration delay, supplier dependency and weak training before those issues become sunk costs.
The point of the example is not the exact numbers. It is the discipline of using the same boundaries for every option and making the decision drivers visible.
Common mistake and limitation
The exercise should challenge the plan, not assign blame. Leaders need to make dissent safe and respond constructively.
Review whether the result changes under reasonable alternative assumptions. A close or fragile ranking should be presented as such rather than converted into false certainty.
Questions to ask before deciding
- What evidence would change the preferred option?
- Which consequence is missing because it is difficult to measure?
- Could a threshold or constraint override the numerical result?
- Who receives the benefits and who bears the costs or risk?
- When should the decision be reviewed?
Professional context: Legal, tax, investment, safety, medical, engineering and regulated decisions require qualified, jurisdiction-specific advice.