The notebook for the choices that weigh
The decision journal.
When a decision goes wrong, your memory acquits you with a "deep down, I knew it". When it goes well, it promotes you to prophet. The journal blocks that trick. Before you decide, you write what you choose, which alternatives you discarded and what you expect, probability in percent included. Six months later you reread it and find out how you really decide. It is the notebook Kahneman recommended to anyone who wanted to decide better. Ten minutes in your own words, no email, no account.
Why it works
Write first, judge later.
Take an example. Six months ago you said no to a permanent job to keep your own project. Then a big client vanished and the year ended badly. Today your memory swears "the signs were all there". Not true. That day you had different numbers in front of you, and with hindsight your head rewrites them. Researchers call it hindsight bias. The journal beats it in one way only: it freezes what you actually knew, with your signature and the date.
The probability you write today is the one piece of data you will not be able to doctor tomorrow. If you sign a "70%" and things go south, you will not be able to tell yourself that deep down you had doubts. And entry after entry those numbers tell you what your confidence is worth, something you never find out without numbers. For the same reason I ask how you feel while you sign: the state you sign in ends up inside the decision, and to see it you must have written it down.
Two rules so it lasts. Write in words so simple that an 8-year-old would understand them. If you need a complicated turn of phrase, you have not understood the decision yet. And keep the journal for the choices that weigh, because if you open it for everything you will abandon it within a week. The real value arrives after four or five reviewed entries: that is where you see your patterns, where you overrate yourself, in which state of mind you sign your worst decisions.
New entry
The decision in front of you.
Fill it in before you decide, or the same day at the latest. Write the way you talk: the journal is yours, nobody reads it. And keep it for the decisions that weigh.
Everything stays on your device. No account, no email, no cloud. One caution though: if you clear your browser data, the journal empties. Every now and then use Copy or Download the PDF to put the important entries somewhere safe. The PDF is a document of your own, laid out and printable, and nobody can take that copy away from you.
Your journal
My decisions.
The entries saved on this device, ordered by review date.
The sources
Where this exercise comes from.
Michael Mauboussin, who has studied investors' decisions for thirty years, asked Daniel Kahneman, Nobel laureate and father of the research on cognitive biases, one single question: what is the one thing to do to decide better? The answer was to go to a stationery shop, buy a notebook and track your own decisions. Not a course, not software. A notebook. This exercise is that notebook.
The structure of the entry follows the Farnam Street decision journal: the decision and the situation, the alternatives seriously considered and why they were discarded, what you expect with a probability in percent, your physical and emotional state at the moment of signing, the review date. Watered-down versions skip exactly the parts that make the difference, that is the alternatives, the numbers and the body.
At the poker table it happens every night. You play the hand the right way, your opponent draws the only card that saves him, and the pot goes to him. The hand was still played well. Annie Duke, former professional poker player and author of Thinking in Bets, gave a name to the mistake of judging it by the pot: resulting, judging a decision by its outcome. A good decision can end badly, and a terrible one can end well. That is why the review here asks two separate questions, how it went compared to the prediction and whether the process was good regardless. Hindsight would do the rest, rewriting what you "already knew": researchers call it hindsight bias. The journal beats it because it freezes what you actually knew.
This is not a clinical tool, it is a notebook with the right questions. If a decision is crushing you, talking to a professional is worth more than any journal.
What now?
The journal is the start. Then comes the method.
The journal is the D of Data of my method, applied to yourself: the facts about how you decide, put in writing before your memory tidies them up its own way.
Who is behind this
Dr. Donato De Tullio. For more than ten years I have been running projects in large European multinationals, and I sign decisions every week: the journal is how I stopped retelling them to myself afterwards. Today I manage 8 logistics centers across Europe. It's all on my LinkedIn.
Alongside my job as a manager, I help people who run their own project decide and move, with the 5D Method. If you want a steady partner at your side, there is Decision Lab, the one-on-one decision-making program.
Written your first entries?
Let's reread them together.
30 minutes, free, over a virtual coffee. You tell me about the decision in your journal and we look together at what your entries say. In English, Italian or German.
I stopped asking for email addresses in exchange for resources: the journal is yours, the entries too, and they stay on your device without leaving contact details. If it helped, try the other practical exercises, have a look at the book Stay or Leave?, and we can always talk over a coffee.