Decision journal: record a choice, then check it honestly

Six months after a big choice, almost everyone remembers it wrong. If it worked out, it feels like you were sure from the start. If it didn't, it feels like you had a hunch and ignored it. A decision journal exists for exactly this: write down what you think and expect before the outcome is known, then compare it with what actually happened.

It sounds like bookkeeping, but it takes five minutes. Below is a decision journal template, an example entry, and a way to review decisions so that a year later the record is useful rather than embarrassing.

Why memory lies about decisions

In 1975, psychologist Baruch Fischhoff gave people descriptions of historical events with several possible outcomes. Some were told how things ended, others weren't, and everyone rated how likely each outcome had been.

People who were told the outcome rated it as much more likely from the start. And they were largely unaware that knowing the outcome had changed their judgment.

This is hindsight bias, the "I knew it all along" effect. The nasty part is the second half: you can't see it from the inside. You sincerely remember being confident, when in fact you were torn.

Daniel Kahneman, the Nobel laureate who spent his career on errors of judgment, said on The Knowledge Project podcast in 2019 that people who make a lot of decisions should keep track of them and of how they turned out. Then he added that people hate doing this, because in retrospect they may look foolish. Which is exactly why it's worth doing.

A decision journal template

Write the entry at the moment of choosing, while the outcome is still unknown.

1. Date and the decision in one line. "Accepting the offer from the other company."
2. Context. What you know now, what you don't, what state you're in. Tired, angry, being rushed: that's part of the decision too.
3. Options. What else was on the table and why it lost.
4. Expectation. What you think will happen and why. The more specific, the easier it is to check later.
5. Confidence as a percentage. 60% and 90% are very different decisions, even though both sound like "I think it'll work."
6. Review date. When you'll know how it went. A purchase needs a month; a job change needs six.

A decision journal example

This entry is made up, but it's built the way an entry should be.

March 3. Decision: moving to an apartment closer to work, rent 20% higher.

Context: the commute is an hour and a half each way, I'm worn out, and there's nothing left in the evenings. The landlord wants an answer by Friday.

Options: stay put; keep looking for another month. Staying means another year of this. Looking longer is risky, good places go in a day.

Expectation: a free hour every evening, back to the pool. The money works if I order less takeout.

Confidence: 70%. Review: June 1.

And the review three months later:

June 1. The hour really did free up. Pool once a week, not three times. Takeout same as before, money is tight. Half matched. Lesson: time frees up easily; habits don't move house with you.

How to review decisions without beating yourself up

The main trap in a review is judging the decision by its outcome. Former professional poker player and decision researcher Annie Duke calls this "resulting": judging the quality of a decision by the quality of a single outcome.

A good decision can end badly because luck went the other way. A bad one can work because luck was on your side. So in a review it helps to split two questions:

• What happened? Did it match the expectation?
• What was down to the decision? What was unknown back then but knowable, and what couldn't have been known at all?

If you used everything you could have known and it still went badly, that's bad luck, not a mistake. It's worth recording too, just without blaming yourself. If the outcome was good but the entry shows you were gambling blind, that's a reason to treat a similar win with more caution next time.

Before a big decision there's one more thing to try: imagine it's a year later and it all fell apart, and write down why. There's an experiment behind this. In 1989, Mitchell, Russo and Pennington found that when people imagine an event has already happened, they come up with roughly 30% more reasons for why it could have happened. That's the number of reasons, not the accuracy of a forecast, but for a decision journal it's exactly what you want: to see risks you would otherwise miss.

Which decisions to write down

Not all of them. There's no point logging what to have for lunch. Write down the ones that:

• are hard to undo: a move, a job, a big purchase;
• repeat: hiring, choosing a contractor, a conversation you keep putting off;
• have you torn right now, stuck between options.

If the decision is already behind you and you want to understand why it won't let go, that's a different kind of writing. A thought diary helps there, and there's a separate piece on why we regret what we didn't do.