Methodology

Every piece we publish answers a chess question with evidence you can check. This page explains where that evidence comes from and how we check it before anything is published.

The master database

Master-game numbers come from the ChessCanvas master database: 15,206,317 games in its current build. It covers OTB 1996–2026 · Online Elite 2024–2026. Over-the-board games and online games are kept apart as separate populations, and every number we publish says which population it describes. Unless a piece says otherwise, numbers describe Modern masters · OTB: over-the-board games, classical or with no recorded time control.

Games are looked up by position, not by move order, so a position reached by different move orders is counted once. Our guide Same position, different order explains the rule.

White's score is the share of points White took: a win counts one, a draw a half.

Master statistics describe what happened in a population of strong players' games. They are not a prediction for any one player or game.

The engine

Engine values come from Stockfish 19 Lite, the same single-threaded engine that runs in ChessCanvas, at a fixed node count stated with each value (normally 2,000,000 nodes). Values are in pawns from White's point of view: a value of one means White is about a pawn better, and a negative value favours Black.

The claims ledger

Every number, engine value and factual claim in a piece is one row in its claims ledger: what is claimed, the value, its source and how it was obtained. A page cannot show a number that is not in its ledger: our build fails if it finds one. Each piece ends with a Sources and evidence table listing every row it uses.

Checks before publication

Every time a page is built:

• every board is replayed move by move, and an illegal move stops the build;
• every master-database number is re-read from the live database and must match exactly;
• every engine value is re-run and must match within ±0.15 of a pawn, because repeated searches vary slightly;
• every link to another site must open;
• facts about people, events and history need a cited source; anything we cannot source is left out.

A piece with an open item cannot be published. A person then reviews the piece before it goes live.

AI assistance

Pieces are researched with ChessCanvas tools and written with AI assistance. AI never decides a fact: the ledger and the checks do, and a person reviews every piece. Each piece says so in its footer.

Corrections

If we get something wrong, we fix it, mark the piece "Updated" with the date, and record the correction here.

Corrections log

No corrections yet.

Sources and evidence4 checked claims

Every number in this article, where it came from and how it was checked. Master-database numbers are re-read from the live database and engine values re-run whenever the page is built. How we check

Claim	Value	Source
Games in the current build of the ChessCanvas master database	15,206,317	ChessCanvas master database manifest, build c7ccea3a87ef (re-read at build)
The periods the master database covers	OTB 1996–2026 · Online Elite 2024–2026	ChessCanvas master database manifest, build c7ccea3a87ef (re-read at build)
The node count used for published engine values	2,000,000	publishing policy; every engine row in every ledger states its node count; this is the default
How far a re-run engine value may differ from the published one	±0.15	publishing policy; DEFAULT_TOLERANCE in site/publishing/src/claims.mjs