Start here · Lesson 8 of 10

The verifiable ledger

A forecast is logged the moment it is made and never edited or deleted. Then it is scored automatically at its horizon. Nothing is quietly dropped when it turns out wrong.

To make that promise checkable instead of trusted, we hash each day's forecasts into a single daily root and publish it. Anyone can recompute the same root from the public data; if one stored value had been changed after the fact, the root would no longer match.

The recipe and the published roots are on the methodology page. This is what 'append-only and verifiable' actually means, spelled out.

See also: immutableWritten once and never changed — a forecast can be scored but never edited or deleted after it's issued., point-in-timeAs it was known on that date — no hindsight; membership and data reflect what was true when the forecast was made., resolutionThe scheduled day a forecast is graded against what actually happened — automatically, with no edits.