How to set estimates and notes

Step 3: give every uncertain number a range, and record where it came from.

Estimates is an editable grid of everything you know or assume, grouped by section (for example Demand, Delivery, Money).

1. Find the estimate

   Search by name, or use Needs attention to list estimates still missing a value or evidence.
2. Choose how you describe it

   Select the estimate to edit it on the right (tabs: Estimate, Evidence, History). The choices are explained in Choosing how to describe an estimate.
3. Record the unit, basis, owner and evidence

   The basis is observed here, external evidence or working estimate.
4. Read the read-back

   Expand the row to see a plain-language sentence of what the model understood. Confirm it says what you mean.

Anything marked not yet known blocks the run, so nothing is silently treated as zero.

Notes on an estimate

Keep an estimate’s description to one sentence plus “See [[note title]]” (240 characters at most). Put the evidence and the reasoning in a note. Saving an estimate with web sources, or accepting a research proposal, writes the evidence note for you. Editing notes or descriptions does not make saved runs out of date.

Tips for honest ranges

• Set the range so you would be surprised if the true value fell outside it, not so it is safe.
• Write the low end first. People anchor on the likely value and set ranges too narrow.
• Use Calibration & Training to check how your own ranges have performed. See Calibration.

Research

Research starts from an estimate, an arrow or the options list, and never changes the model by itself. It leaves evidence and a proposal, and nothing changes until the owner accepts it. See Research sources.

Next: Why ranges, not single numbers