📊 Data Sources
Data Sources
What public data sources and assumptions are used for global trait estimates.
Method FAQ
Is Avortas scientific research?
No. It’s an educational, curiosity-first calculator that uses probability-style thinking.
Why do you use 8.2 billion?
It’s a simple global population frame to make comparisons intuitive.
How can I interpret results responsibly?
Treat them as estimates and entertainment—real-world distributions are complex.
Where these numbers come from
Avortas is a curiosity tool, not a research instrument, and its figures differ a great deal in how solid they are. This page says which is which, because a number presented without that context is worth less than no number at all.
Population. United Nations World Population Prospects and World Bank indicators, which themselves draw on national censuses. Firm. The figure on each country page is rounded from one of them, and where a country’s own census is old, that page says so.
Adult height. Pooled national health surveys, principally the NCD Risk Factor Collaboration, and individual national surveys where a country runs one that measures people rather than asking them. Firm.
Blood type. National blood services, Red Cross and Red Crescent societies, and published donor and hospital studies. Real sources exist for most countries, but they disagree with one another, and the percentages on our country pages are rounded approximations that will not match any single published study exactly. Where a country page cites specific research, that research is named on the page.
Eye colour and hair colour. No national statistics office anywhere collects these. No census asks. These are the softest numbers on the site: estimates drawn from survey and academic literature, useful for the rough pattern of a country and not to be read as measurements.
Names. Where a country page gives a surname count it comes from that country’s own register or statistics office, named on the page. The global first-name and surname lists behind the name tool come from published frequency compilations.
Wealth and income. World Bank income and poverty data and published global wealth reports.
Personality types. Published academic work on the Big Five, plus frequency figures released by commercial test publishers. The latter are self-selected samples of people who chose to take a test, not population statistics, and are worth reading as such.
Birthdays. National birth registration data and published studies of birth seasonality.
What we do not do is invent a figure or dress an estimate as a measurement. Where a number is an estimate, the page carrying it says so — the rarity calculator states its own assumptions every time it returns a result. See also how the calculation works and what the probabilities mean.
Last reviewed September 2026.