Data sources and methodology

The curated tables were assembled from published exchange and block-chain records, then cross-checked wherever two independent sources cover the same period. The method was deliberately conservative: where sources disagreed, the site took the series that could be re-fetched and re-verified, and recorded the disagreement rather than averaging it away. No figure on this site has been interpolated, smoothed or modelled. If a price is not attested by a source, it does not appear.

The early years required the most judgement. Before 2015 there was no single dominant exchange, and the quoted price of bitcoin differed materially from venue to venue — sometimes by more than twenty per cent on the same day. For 2010 to 2014 the site uses Bitstamp and CoinDesk historical series, which are the most complete surviving records for that period, and every table that reaches back that far says so in its provenance line. From 2015 onward the figures come from Coinbase Exchange daily candles, which are published in a consistent format and can be re-fetched at any time.

The halving records are the most secure of the curated tables, because the underlying facts are on the block chain itself. The dates, block heights and subsidy amounts are protocol facts that anyone can verify against a node. Only the price around each halving is a market figure, and it is labelled as approximate for that reason. The milestone timeline is the least quantitative table on the site: it is a dated narrative drawn from contemporaneous public reporting, and its value lies in the chronology rather than in any number it contains.

Every figure on the site is traceable to a published source, and every source is named. A table carries the source it was compiled from and the period it covers; a research article names the datasets it rests on. The register above is the single list of those sources, and it is served from the same metadata the tables themselves carry, so it cannot drift out of step with the data.

Where two sources disagree, the disagreement is recorded rather than averaged away, because the fact that a number is contested is itself useful information. Where a claim rests on a protocol fact — a block height, a subsidy amount, a halving date — it is treated as verifiable against the block chain and stated without hedging. Where a claim rests on interpretation, it is written as interpretation with the reasoning shown.

The sourcing standard itself is set out on the editorial standards page, and the method behind the compiled tables is on the methodology page.

Every dataset carries a vintage: the period it covers and the point at which it was last republished. A material update — a revised source, a corrected figure, an added year — moves that vintage forward and is dated. The date is the date of the update, not the date of the original publication, so a reader can tell at a glance how current the material is.

Curated material is reviewed each quarter and whenever a source is revised. The live series are the exception: the spot price and the daily candles are readings fetched from the Coinbase Exchange public API, cached for a few minutes and re-fetched on demand. They change between visits and are not stored as history, so they carry a fetch timestamp rather than a vintage.

How a correction is reported, reviewed, verified and published is set out on the corrections policy page.

Curated data does get revised. When a source publishes a correction, or when a re-fetch against the Coinbase API returns a candle that differs from the one previously recorded, the site updates the affected table and moves its vintage label forward. It does not silently overwrite the old figure and pretend the change never happened: a revision is a fact about the record, and the vintage range on each table is there so a reader can tell which version they are looking at.

The live series are not revised, because they are not stored as history. Each fetch replaces the cached value, and the previous reading is gone. If you need a permanent record of a particular day's price, take it from the curated daily candles rather than from the spot panel, and note the date you captured it.

The editorial standards page sets out how corrections are handled in the writing itself, and what the site does when it gets something wrong. The short version is that it says so, on the page, rather than quietly editing the claim away.