What is a decision journal?
A decision journal is a record written at the moment of deciding that captures the decision, the expected outcome, and the decider's confidence, so judgment can later be compared against what actually happened. It exists to counteract hindsight bias and outcome bias.
What do you write in a decision journal?
At decision time: the situation, the decision, the expected outcome phrased so it can actually be wrong, the confidence level, and the main assumptions. At review time, typically a set date later: what happened, which assumptions held, and what that says about the reasoning. The falsifiable expectation is the load-bearing part; vague expectations make every decision score as a success.
Who uses decision journals?
The practice comes from investors and professional poker players, fields where outcome quality and decision quality visibly diverge, and was popularized by writers including Daniel Kahneman, Annie Duke, and Shane Parrish. Teams adapt it by making the unit of record the team decision, with stakeholder positions standing in for private confidence levels.
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