Estimate before the number arrives

When it fits

• You need a numerical estimate and have not yet seen the suggested number.

When to avoid it

• If you already saw the number, do not reconstruct an 'independent' estimate after the fact. Use separate evidence or another estimator and disclose the exposure.

Why it matters

Before you see a suggested number, write your own range and the assumptions behind it. Then compare evidence, not authority. If the new estimate reveals something you missed, update. If it only supplies a number, that is not yet a reason.

Steps

1. Define the quantity, units, scope, and time period.
2. Use comparable cases or a task breakdown to write a range and key assumptions.
3. Read the suggested number. Compare its assumptions and evidence with yours.
4. Keep both estimates and record why you changed — or did not change — your view. Compare them with the eventual outcome when possible.

Check your result

Was the first range recorded before exposure? Can every later change be traced to new evidence or an explicit assumption?

Keep this limit in mind

• If you already saw the number, do not reconstruct an 'independent' estimate after the fact. Use separate evidence or another estimator and disclose the exposure.
• This general reasoning aid does not replace professional advice in high-stakes decisions.

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