Methodology
How we score and rank jurisdictions
The Oyster Score
The Oyster Score is a composite index designed to provide a single comparable metric across all jurisdictions. It is the unweighted average of three equally weighted pillars: Health, Freedom, and Security. Each pillar aggregates multiple institutional indicators normalized to a 0-100 scale, where 100 represents the best observed performance globally.
The score intentionally excludes cost of living and GDP — these are presented separately because their interpretation depends on individual circumstances. A low cost of living is desirable for retirees but may signal underdevelopment; a high GDP does not guarantee quality of life. By focusing on health, freedom, and security, the Oyster Score captures aspects of life quality that are universally valued.
Scoring Pillars
Inputs: Healthcare Quality (WHO), Life Expectancy (WB), Healthcare Access (WHO)
Inputs: Press Freedom (RSF), Speech Freedom, Internet Freedom, Assembly Freedom, Religious Freedom (Freedom House)
Inputs: Judicial Independence (WJP), Corruption Index (TI), Property Rights, Political Stability (WB)
Normalization Process
Each metric within a pillar is normalized to a 0-100 scale using min-max normalization across all jurisdictions with available data. For metrics where lower values are better (e.g., infant mortality, corruption), the scale is inverted so that 100 always represents the best outcome.
Within each pillar, the normalized metrics are averaged with equal weight. The final Oyster Score is the unweighted mean of the three pillar scores. Jurisdictions missing data for an entire pillar are excluded from the overall ranking but still appear on individual metric pages.
Cost of Living Index
The Cost Index shown on the rankings page is a separate metric not included in the Oyster Score. It represents relative price levels derived from purchasing power parity data published by the World Bank. The index is normalized so that the global median equals 50. A value of 80 means prices are roughly 60% above the median; a value of 30 means prices are roughly 40% below. City-level cost of living breakdowns (rent, food, transport) are compiled from multiple reference sources including price surveys and public records.
Data Sources
| Source | Coverage |
|---|---|
| World Bank | GDP, inflation, unemployment, education, infrastructure, demographics |
| WHO | Life expectancy, mortality rates, healthcare quality, health expenditure |
| Freedom House | Political rights, civil liberties, press freedom, internet freedom |
| Transparency International | Corruption Perceptions Index |
| OECD | Tax rates, trade data, education metrics, social indicators |
| IMF | GDP forecasts, fiscal indicators, exchange rates |
| Henley & Partners | Passport rankings, visa-free access counts |
| WAQI | Real-time air quality index for cities |
| WeatherAPI / Azure OpenAI | City weather data and monthly climate averages |
Update Frequency
Data is refreshed quarterly. Some indicators publish annually (GDP, education enrollment, freedom indices), while others update more frequently (inflation, interest rates, air quality). Each data page shows a "Last Updated" date reflecting when the underlying source data was last incorporated. Rankings are recomputed after each quarterly data refresh.
Limitations
No single index can fully capture what makes a jurisdiction suitable for a particular individual. The Oyster Score provides a starting point, not a definitive answer. Data availability varies by jurisdiction — smaller nations and territories may have gaps. City-level data (prices, safety scores, neighborhoods) is compiled from multiple sources and may vary from on-the-ground conditions. We recommend cross-referencing with local sources when making major decisions.