How well calibrated is Polymarket 24 hours before resolution?

What the measured evidence supports

At a 24h lead, the archived Polymarket sample contains 965 resolved binary markets and has a Brier score of 0.0904. This is descriptive calibration, not a forecast.

These are historical frequencies measured over the observed window. They describe what the sample did, and carry no claim about any individual case.

The sample is taken at a fixed lead time ahead of resolution, so it describes that vantage point alone and not the whole life of a market.

Readers and agents can inspect the companion dataset, follow the public methodology, and query the API from the links below.

This answer applies only to the observed sample, measurement window, and coverage stated by the linked methodology.

Interpretation should preserve the caveats attached to every used claim rather than generalize beyond available coverage.