Concept
The decision journal
A decision journal is one page per consequential decision, written before the outcome is known: the options, the assumption tested, a numeric probability, the advice you would give a friend, a premortem and a review date. Memory cannot rewrite it, and the Make Better Decisions road ends by building one.
Annie Duke and the Heaths reach the same conclusion from different directions: the only way to improve at decisions is to make them visible to yourself at the time and afterwards. Memory rewrites every decision into a story in which you knew then what you know now. The journal defends against that with six questions. What is the decision, with at least three options. What assumption am I betting on and how did I test it. What is my probability that it works out, and what does that mean specifically. What would I tell my best friend. It is a year later and it failed; why (a premortem). On what date or at what number will I review (a tripwire). Four or five entries a month is plenty; read together, they show patterns no single decision can.
A real-life example
After a month a manager has five entries: a job, a flat, a hire, whether to report a colleague's mistake, and a loan to a cousin. Read together they show one pattern already: his probabilities are honest at work and ten points too kind with family.
How to use it
- 1One page, six questions, written before the outcome is known.
- 2Put the review date in your calendar as you write the entry.
- 3At the end of each month, read all entries together and look for the error you keep letting in, such as too few options or too much confidence.