The Polymath Experiment

Decide · 04 · Field manual · PDF

The Decision Field Manual

How to decide well when it matters, and learn from how it turns out.

The job offer, the school, the repair or the replacement, the hire. This manual gives you a short, repeatable way to make the few decisions a year that really matter: find the real question, widen the options, decide what matters before you compare, weigh the worst case, and write down what you expect so every decision makes the next one better.

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The Decision Field Manual cover, with a repair bill drawn as three options, a worst case and a month of evidence

Decide · 04 · One idea, drawn twice

Draw it as it feels, then as it works

The manual uses the same grammar as the book: the decision as it's framed, then the options and costs it hides. Here's a pair from the book, Chapter 1 of The Decision Engine.

16 seconds · the first drawing, then the redrawingA print shop owner at sixty-four with no successor named: waiting looked like no decision, until the people who needed an answer made it instead.

The method: weigh the decision

  1. What exactly am I deciding, and by when?
  2. What are my real options? At least three, including waiting or testing.
  3. What matters most? Criteria, before comparing.
  4. What could happen? The likely, the best and the worst.
  5. How much is at stake, and how reversible is it?
  6. What do I expect, and when will I check?

How professionals decide

Every unit has a professional's view: how insurers, clinicians, engineers, investors and poker players structure the same kind of choice, translated for ordinary decisions. Then three field cases, a hire, a school and a group decision, a printable Decision Canvas and a Decision Journal you can use for years.

Size the decision first: most choices deserve a minute, not a method. This manual is for the few that are big and hard to undo.

Eleven units, one sentence each

Decide · 04.01 – 04.11
  1. 04.01FramingA choice between two options is usually a choice nobody has finished thinking about.
  2. 04.02SizingSpend your analysis where a choice is big and hard to undo.
  3. 04.03Opportunity costEvery yes spends something you could have used elsewhere. Name it.
  4. 04.04Criteria firstDecide what matters before you look at the options.
  5. 04.05Expected valueWeigh outcomes by their odds, then check the worst case alone.
  6. 04.06Decision treesDraw your choices and chance's outcomes as separate branches.
  7. 04.07The value of informationOnly gather information that could change what you'd do.
  8. 04.08Sunk costsWhat's spent is spent either way. Decide on what comes next.
  9. 04.09And then what?Ask what happens after the first effect, at least twice.
  10. 04.10Decisions and outcomesJudge a decision by what you knew, not by how it turned out.
  11. 04.11The decision journalWrite down what you expect before you know how it turns out.

Inside the PDF

A5 pages · read on screen or print at home
Part 1, Weigh the Decision: the six questions, worked through on an old car that needs a costly repair.
Unit 06, Decision Trees: insulate now or wait for a grant, with the chance outcomes inside an ochre boundary.
Field case B: two parents choosing between two secondary schools, scored against criteria written first.
The Decision Journal: one entry, from the decision and the expectation to the review and the lesson.

Where it fits

The manual is the entry to the Decide stage; the book, The Decision Engine, goes deeper, and you can get both as a set for €39. When a decision is stuck because it frightens you rather than because it's unclear, The Fear & Uncertainty Field Manual is the companion. To see the system around a decision before you make it, try The Systems Field Manual, and to check the facts it rests on, The Thinking Field Manual.

Start free

The way of thinking behind this manual grows out of The Polymath Bible, which is free. Get the book and a weekly letter with one idea, one diagram and one exercise.