Keep this life skill for later
Sign in to save
← All life skills

Learning & thinking · a life skill

Deliberate Assumption Listing

a map of what the plan needs, and what you know

A list of assumptions is a start. Put them on a map instead: how much the plan needs each one, against how much you actually know. Test the corner where those disagree, with a test you could fail, and move the notes every week until a checkpoint.

  • Moderate to start
  • High impact
  • Learn it in 2-4 weeks
  • Twenty minutes a week
  1. Wk 1

    Baked before work at 5am.24 loaves by 8am, not 30.30 loaves → 24

  2. Wk 2

    Offered pre-orders to 20 neighbours.14 paid up front. The test needed 12.people pay £4 → known

  3. Wk 3

    First Saturday at the market.Sold 22 of 24 by noon.pre-orders + stall → known

  4. Wk 4

    Checkpoint.Still fun, mostly. Tired on Sundays.change: 24 loaves, pre-orders first

a bread stall's assumptions, on the map
An assumption map: how much the plan needs each assumption, against how much you know The plan is a Saturday bread stall for four weeks, with a checkpoint at week 4. Five sticky notes sit on a map. Up the side: how much the plan needs it. Along the bottom: how much you know. The top-left corner, needed but unknown, is marked test first. It holds “people pay £4 a loaf” and “still fun after a month of 5am starts”. Top right: “30 loaves by 8am”, crossed out and changed to 24 after week 1. Bottom left: neighbours tell their friends. Bottom right: the pitch costs £20 a week. A test card for the £4 note says: offer pre-orders to 20 neighbours, right if 12 or more pay up front. In week 2, 14 paid, and the note moves right. At the checkpoint the plan is stamped change. A Saturday bread stall for four weeks · checkpoint at week 4 the plan needs it you know it test first needed, known keep an eye on fine people pay £4 a loaf still fun after a month of 5ams 30 loaves by 8am neighbours tell their friends the pitch costs £20 a week test card · people pay £4 a loaf test offer pre-orders to 20 neighbours right if 12 or more pay up front by the end of week 2 [wk 2: 14 paid] people pay £4 a loaf 24 [only week 4 can tell] CHANGE

The corner is where the plan's weight meets your ignorance. A note leaves it only one way: a test you wrote before you ran it, which came back.

For a plan you'll run for a month

Map it, then test the corner.

A side project, a new routine, a move. Something you can try for a few weeks and then decide about.

  1. Write the plan, and a checkpoint

    Put a date on the plan when you'll decide whether to carry on, change it, or stop. Three or four weeks is long enough to learn something and short enough to remember why you started.

  2. One assumption per note

    Finish “this works only if…” on sticky notes or scraps of paper. Include the ones about people (will they buy, will they help), the ones about you (time, energy, how much you'll enjoy it), and money.

  3. Place each note on the map

    Up the side: how much the plan needs it. Along the bottom: how much you know it, from something you've seen, not felt. The top-left corner, needed but unknown, is the only one you test this month.

    If a note is hard to place, it's usually two assumptions. Split it.

  4. Write a test you could fail

    For each corner note: the cheapest test that would show it's wrong, the result that counts as right, and a date. Write “right if” before you look. A test with no way to fail is a hope with paperwork.

  5. Move the notes every week, then decide

    Once a week, slide each note to where the evidence now puts it, and change the plan when one turns out false. At the checkpoint, read the map: go on, change, or stop.

Thinking of moving to a new town? Before you sign a lease: “the commute takes under an hour” goes in the corner. Test: do it twice at rush hour. Right if both runs come in under 60 minutes.

Try it on yours

Map your plan.

Write up to six assumptions and place each one. The map fills in as you go, and the first note in the top-left corner gets a test card to fill in.

    test first
    needed, known
    keep an eye on
    fine

    Nothing you type is saved or sent anywhere. Copy the card before you leave the page.

    Why “right if” comes first

    The same result, read two ways.

    Rita McGrath and Ian MacMillan, writing in the Harvard Business Review in 1995, argued that a plan for something new is mostly assumptions, and should be run as a way to turn them into knowledge as cheaply as possible, with checkpoints where you decide whether the next step is justified. Their “discovery-driven planning” only works if the checkpoint can say no. Here's the bread stall's week 2, run twice.

    “Right if” written before the test

    1. Monday: right if 12 of 20 neighbours pay up front.
    2. Friday: 9 paid.
    3. So: the £4 note stays in the corner. Try £3.50, or a different street, before booking a pitch.

    The test could fail, so it told you something.

    No line drawn until after

    1. Monday: “let's see how many want one.”
    2. Friday: 9 paid.
    3. So: “9 is a decent start for week 2.” The note drifts right. The pitch gets booked.

    Any result would have counted as a pass, so it told you nothing.

    The idea

    Why it works.

    A flat list treats every assumption the same, so you check the easy ones and feel thorough. The map sorts them by the two things that matter: what happens to the plan if this is wrong, and whether you'd know. The corner where both are bad is usually two or three notes, which is a month's work, not a year's.

    Moving the notes each week is the deliberate part. It turns a plan into a record of what you've learned, and it makes the checkpoint easy: a plan whose corner has emptied is ready to grow, and one whose corner is still full is not ready to spend more on.

    Keep it honest

    Habits that help.

    • Evidence means something you saw. “Everyone loves fresh bread” is a feeling. “14 paid” is evidence.
    • Test with money or time. People are kind when it's free. A pre-order or a booked slot tells you more than a like.
    • Cheapest test first. If a phone call could settle it, don't build anything yet.
    • Keep the old maps. Each week's photo shows how far the plan has really come.

    Go deeper

    Keep going.

    Practise this in HourLife.

    In Decisions: Assumptions. 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