The Rules

The Crossbook Record is a permanent public record of dated probability predictions on prediction markets, each one evaluated on its resolution against the market price at the time the prediction was made. These are the rules it operates under. Hold Crossbook accountable to them.

1. 01

   Disagreement required

   Crossbook only records a prediction when its number differs from the market price by at least 3 points at the time it records it. Smaller differences are noise, not forecasts. They never appear in the record, public or private. If the market moves toward its number after it records one, the prediction stays.

2. 02

   Timestamped or it does not count

   A prediction only enters the record if it was published before resolution, with a timestamp Crossbook cannot change afterward. No exceptions.

3. 03

   Losses first, always

   Crossbook never removes a bad prediction. Resolved losses are listed before wins in every weekly Record. The bad predictions, prominently displayed, are the product.

4. 04

   Scored against the market

   Every prediction is evaluated on its resolution against the market price at the time it was made, with a running Brier score versus the market baseline, published whatever it shows.

5. 05

   No false precision

   Crossbook never uses the words “arbitrage” or “risk-free” about a pair of markets it has not confirmed share an identical settlement basis.

6. 06

   Commentary, not advice

   Everything here is published-to-all analysis. No personalized advice, no portfolio imports, no copy trading, no execution.

Definitions

Market price

The current price on the venue named in the prediction, at the time the prediction is recorded.

Resolution

The official settlement outcome of the venue the market trades on. If two venues in one prediction settle differently, each is scored against its own settlement.

Market baseline

The Brier score the market price itself would have earned over the same set of predictions. Beating it is the entire claim.

Change policy

These rules are versioned and dated. Any change applies only in the future: predictions recorded before a change are scored under the rules in effect when they were recorded. Every change is listed in the changelog below. A rule change can never remove or edit a recorded prediction.

Changelog

• August 30, 2026

  Eleven of the forty-one scored predictions were written inside the 48-hour window, and they still count. Keeping them makes the score slightly better, not worse. An audit of every entry against the window found twenty-two written with less than 48 hours’ notice. Eleven were caught by the August 22 correction and count toward nothing. The other eleven predate the window entirely, and the rule directly below this changelog says a prediction is scored under the rules in force when it was recorded — so they are scored, including one written six minutes after its event began. The August 22 entry did not say this and reads as though no such entry survives. It does, and a reader should not have had to check. They are not being removed, and the number is why the decision needs showing rather than asserting. Those eleven score 0.1677 between them, which is better than the record as a whole. Dropping them would move the Brier from 0.1795 over 41 to 0.1838 over 30, and the gap to the market from 0.0113 behind to 0.0125 behind. Keeping them therefore flatters Crossbook on both figures, which is the direction that obliges disclosure. Each is now labelled on its own row in the record, with how far ahead of the event it was written. Separately, the two dates a contract carries are now told apart everywhere. A market has an event date and a settlement date, and on Polymarket game markets they differ by up to a week — measured across 100 live markets, 33 of the 73 fixtures settle later than the event, baseball consistently by seven days. Crossbook stored only one of them and showed it unlabelled. Both are now recorded and named: the record counts down to Contract settles, because that is when a call can be graded, and the screener counts down to Event date, because that is the last moment a forecast means anything. The 48-hour window still uses the earlier of the two, which is unchanged and is what stops a finished game being forecast for the week its contract takes to settle.

• August 22, 2026

  Eleven entries stopped being scored, and the score improved sharply as a result. Both halves of that sentence matter. Crossbook refuses to record a prediction inside 48 hours of resolution, because a number written after late information arrives is not a forecast. That check reads the market’s closing date, and the closing date was wrong: Polymarket publishes a date that is the event plus a dispute buffer, up to 31 days of it, so finished games looked days away and were accepted. Eleven predictions were recorded after the event they were about had already begun. They are not forecasts and can no longer be scored as if they were. They stay in the record, visible, each labelled with why it counts toward nothing. Every remaining prediction now carries the real event time, taken from the same date the market’s own rules cite, and the original value is kept alongside it. Removing those eleven moved the Brier score from 0.2557 over 23 resolved predictions to 0.1565 over 14. It also cost Crossbook its lead over the market, and that is the number that matters. Against the market baseline on the same predictions, the record was ahead by 0.0220 before the removal and is behind by 0.0029 after it. The eleven scored 0.4100 between them, which is worse than guessing, but the market scored 0.4706 on those same eleven, so they were the record’s strongest entries relative to the book even while being its worst in absolute terms. Removing them was still right, because a number written after the event has started is not a prediction whatever it scores. But it made the headline look better and the actual claim look worse, and a reader is owed both halves of that. The generation path now refuses on the real event time and separately refuses anything already under way.

• August 20, 2026, v1.0

  Initial publication. On the same day, 22 stored entries that fell below the 3 point threshold were deleted, to bring storage in line with Rule 1. None of them had resolved, so no score changed: the Brier score read 0.1594 against a market baseline of 0.1506 over 12 resolved predictions both before and after. They were never predictions under this rule; they were noise an earlier version of the software kept.