For every country × category we compute the mean, median, 25th/75th percentiles, standard deviation and coefficient of variation.

Minimum is defined as the mean of the cheapest 1st percentile of observations; maximum as the mean of the most expensive 1st percentile — robust to single freak values.

All statistics are stored canonically in USD and converted to your display currency on the fly using daily exchange rates.

Any observation more than 5 standard deviations from the local median is flagged as suspicious — never deleted — and held out of public statistics.

An absolute sanity check catches unrealistic values (e.g. €18/L gasoline, a €0.20 service, a €1,000,000 hotel) using category-specific floors and ceilings, assigning a confidence score.

Suspicious and excluded values are preserved internally so moderators can review them, but they don't distort the public numbers.

Every statistic carries a 0–100% reliability score derived from sample size, data freshness, contributor reputation and dispersion.

A price shown as “€5.43 ± €0.31 · Reliability 94%” is far more useful than a bare average — it tells you how much to trust it.

Each index is a weighted basket of categories. We standardize every category's price across all countries (robust min-max on log prices), take a weighted average, then rescale to 0–100.

100 means the most expensive country in the world for that basket; 0 means the cheapest. The same method powers every map mode and ranking.

The Arbitrage Explorer compares each country's price for a good or service against the global median, producing an opportunity score (0–100) where 100 is the best value on Earth.

Curated decks combine baskets — e.g. cheap rentals + food + gyms for digital nomads — to surface the best-value destinations.