How Compass works

Where the data comes from, what is checked before it's published and how each tool is calculated.

The rules

• Never make up dataIf a source fails or a day of prices is missing, the update stops with an error instead of filling the gap.
• Open sourcesEvery price comes from a public source, named on the page that uses it.
• No advertisingThe project is funded only by voluntary contributions.
• Not adviceIt's educational material: there are no buy or sell recommendations.

Data sources

• Bitcoin, ethereum and solana, daily price ("One dollar a day", "The best day of the week", "Your salary in crypto"): Coin Metrics Community Data, CC BY-NC 4.0 license, checked against the daily close of exchanges such as Bitstamp, Coinbase, Poloniex and Binance.
• S&P 500 (simulator): total return of the US stock market from Kenneth French's data library (CRSP), with dividends reinvested, minus the VOO ETF's 0.03% annual expense ratio. Against the real VOO, the monthly correlation is 0.99.
• Bitcoin and ethereum in the simulator: daily closes from Binance's spot market (BTC/USDT and ETH/USDT), with USDT = 1 dollar.
• Salaries ("Your salary in crypto"): average annual wages from the OECD, the minimum wage from the US Department of Labor and exchange rates from the Federal Reserve and the OECD, via FRED.

What is checked

Before publishing, every series is checked for duplicate dates, missing days and null or impossible prices. Crypto prices are compared day by day with those of other exchanges.

Every time the data or the code changes, hundreds of automated checks run; for example, that with constant returns the simulator matches the exact financial formula. If any of them fails, nothing is published.

How each tool is calculated

• One dollar a day: buys $1 every day, at that day's price, from the chosen date, and values everything at the latest price.
• The best day of the week: assigns each day's return (close versus the previous close, in UTC) to its day of the week and compounds each day's returns separately.
• Your salary in crypto: divides a month of average salary, converted to dollars, by the coin's average price in each year.
• Simulator: "Simulate" shows what actually happened. "Look ahead" gives a range of outcomes using 12-month block bootstrapping: the risk comes from history and the growth is chosen by the person.

Limits

Results are nominal, not adjusted for inflation, and don't deduct fees, spreads or taxes: in real life they would be somewhat lower.

Past results don't guarantee future results. Bitcoin's growth, for example, has been smaller in each cycle.

Educational content. Not financial advice.