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Advanced Decision Trees

a month for a decision that matters

A tree tells you which option looks best today. On a decision you'll live with for years, give it a month: attack the branch you like, find out the one thing that could change your mind, write down what you expect before you know, and review the decision later, not just how it turned out.

  • Challenging to start
  • Life-Changing impact
  • Learn it in 30 days
  • One decision, thirty days

The monthday 1 → 30

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going out on your own, over a month
A decision tree carried through a month: options, a pre-mortem, what to find out, a journal entry, a tripwire and a review The question: how do I go out on my own? Three options: quit in March, go four days a week, or stay a year. Four days a week scores best and is circled. Under it, a pre-mortem asks: a year on, it failed, why? Three cracks: the fifth day filled with admin, no old client said yes, the pay cut bit by month four. That leads to the one thing worth finding out: will two old clients pay? One call each; if not, staying a year wins, so it's worth an afternoon. Then, on day 11, a journal entry: four days a week, 60% it works, feeling nervous but sure. Beside it a tripwire: no paid client by 1 June, rethink. At the foot, day 30: judge what I knew, not how it went. How do I go out on my own? Quit in March worth 5.2 / 10 Four days a week worth 6.4 / 10 Stay a year worth 5.8 / 10 [a year on, it failed. why?] the fifth day filled with admin no old client said yes the pay cut bit by month four worth finding out first Will two old clients pay? One call each. If not, staying a year wins: worth an afternoon. day 11 · journal Four days a week. 60% it works. Nervous, but sure. tripwire No paid client by 1 June: stop and rethink. day 30 · review Judge what I knew, not how it went.

The scores are a 0 to 10 rolled-back value, as on the deliberate tree. The month only adds what a single sitting can't: time to find out, and a record to check against.

The month, step by step

Six moves, thirty days.

  1. Days 1–2

    Draw the tree, with numbers

    Squares, circles, chances and payoffs, as in a deliberate tree. Roll it back and note which branch you favour, and by how much.

  2. Day 3

    Pre-mortem your favourite

    Imagine it's a year later and the branch you favour has failed. Write down why, as if it had happened. Each reason is a crack to check or a chance to lower.

  3. Days 4–10

    Price what you don't know

    For each uncertain chance, ask: if I knew the answer, would my choice change? If it would, and finding out is cheap, find out. If it wouldn't, stop researching it.

  4. Day 11

    Decide, and write it down

    Before you know how it turns out: the options, the choice, the chance you give it, what you expect, and how you feel. Memory will rewrite all of these later.

  5. Day 11

    Set a tripwire

    Name a sign and a date that would mean the bet isn't working: “no paid client by 1 June.” Until it trips, stop reopening the choice.

  6. Day 30

    Review the decision

    Read the entry back. Judge what you knew and how you weighed it, not how it went. Note what you'd do differently next time, then put a later review in the diary.

Day 11

Write the entry before you know.

Fill it in for your own decision. Copy the entry somewhere you'll find it, and add the review to your calendar. Nothing here is saved or sent: it lives in this tab until you close it.

Decision journal
Decision
Options
Chosen
I expect
If it fails, it'll be because
Tripwire
Feeling
Review on

Day 30

A good decision can turn out badly.

Annie Duke, a former professional poker player, calls it “resulting”: judging a decision by how it turned out. Do that, and you'll learn the wrong lesson from bad luck and the right-looking one from good luck. Answer two questions separately, and see which square you're in.

Reading your entry back, was the decision sound for what you knew then?
Has it turned out well so far?

it went wellit went badly sound decision
EarnedDo it the same way next time.
UnluckyKeep the method. Check the tripwire, not your nerve.
poor decision
LuckyEnjoy it, then fix the method before luck runs out.
DeservedThe lesson is in the method, not the result.

Where the month comes from

Three ideas, each older than it looks.

  • Imagine it already happened · 1989

    Deborah Mitchell, J. Edward Russo and Nancy Pennington found that people who imagined an event had already happened explained it in longer, more specific terms than people who imagined it only might. That's why a pre-mortem says “it failed”, not “it could fail”.

  • The pre-mortem · 2007

    The psychologist Gary Klein turned that finding into a team exercise and named it in the Harvard Business Review: before a project starts, everyone writes down why it failed, and the reasons are read out one at a time.

  • The value of information · 1966

    Ronald Howard, at Stanford, showed how to put a price on finding something out before you decide: it's worth what it could change about the choice, and nothing more. Facts that can't change your mind are free to ignore.

Go deeper

Keep going.

Practise this in HourLife.

In Decisions: Options with leanings. Write down a decision, weigh the options, mark the one you chose, and come back later to record how it turned out.

Download on the App Store Download on the Mac App Store How Decisions works in HourLife