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For each uncertain number the app asks “How sure are you?” You never have to pick a statistical distribution; the app chooses a sensible shape from your answer. You can change it later.

The kinds of answer

Hard limits versus a likely range

This is the most important choice, because it decides whether your numbers are walls or only a likely range.
  • Hard limits (lowest, most likely, highest): only shapes that stop at those limits are allowed. See Bounded shapes.
  • A likely range (low, middle, high): only shapes with open-ended tails are allowed, so a surprise outside your range is still possible. See Skewed and percentage shapes.
The app refuses to mix these up. Treating a likely range as hard limits would quietly rule out the surprises you said could happen.

The read-back

Every estimate is read back to you in a sentence, for example “There is a 1 in 10 chance this is below 4 hours and a 1 in 10 chance it is above 12”. Check it before you move on. Next: Bounded shapes