Living Worlds

Research · Lifetimes · Oct 5, 2026

Life expectancy, predicted twenty years ahead

Not met155 countries

The test at a glance

What it tests
Accuracy against reality: life expectancy at birth, twenty years ahead.
Data
UN World Population Prospects 2024, 155 countries of a million people or more; fitted on 1950-1999. The 2024 revision re-estimates the past with later censuses.
Held out
2019 (2009 also reported).
Compared against
No change from 1999; each country's own 1980-1999 trend.
Bar
Mean error at most 1.0 year for both sexes AND 80% intervals covering 70% to 90% of countries.
Result
2.06 years for women, 2.42 for men: not met.

Fitted on 1950-1999 only and scored once on 2019, the forecast came within 2.06 years for women and 2.42 for men across 155 countries, against a registered target of 1.0. Most of what remains is shocks: wars, state collapse and HIV. Registered before scoring, on a year no run had seen. The history it was fitted on is the UN's 2024 revision, which re-estimates the past with later censuses, so these errors are kinder than a forecast made in 1999 would have been. The next tests are set against the UN's own forecast from the same starting point.

Protocol, result and scorer

Protocol Result Crisis-robust protocol Crisis-robust result UN revisions (context)

Next

Forecasts frozen and scored on 2024 national figures nobody had read (the result).

Lifetimes

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