Methodology
How we score and rank jurisdictions
Method documentation version: 2026-09-09 · Reviewed by Oyster List. This version clarifies the existing ranking formula and adds coverage disclosure. It is a method review date, not a data refresh date.
The Oyster Score
On the rankings page, the Oyster Score is the rounded arithmetic mean of the available Health, Freedom and Security pillars. Each available pillar has equal weight. The ranking query uses stored scores intended for a 0–100 scale; it does not apply global min-max normalization. A value of 100 is not a verified claim of the best observed performance worldwide.
Cost of living and GDP are excluded from this score. The three pillars cover selected health and governance proxies, not every aspect of living conditions. Their interpretation depends on your priorities and on the available input coverage.
Scoring Pillars
Inputs: Stored Oyster healthcare quality score. Life expectancy and healthcare access are not separate inputs to this ranking pillar.
Inputs: Rounded mean of available stored press freedom, speech freedom, internet freedom, assembly freedom and religious freedom scores (up to five inputs).
Inputs: Stored judicial independence score only. This is a governance proxy; it does not measure homicide, conflict intensity or personal safety.
Calculation and Missing Data
First, Freedom is the rounded mean of its available five input fields. Health and Security each use one stored field. Then the Oyster Score is the rounded mean of those available pillar scores. Null values are omitted; a numeric zero is retained. If no pillars are present, the score is unavailable. For example, Health 80, Freedom 51 and missing Security produce an Oyster Score of 66, with coverage of 2/3 pillars.
Jurisdictions with missing pillars can still receive an overall score. The rankings show the number of available pillars out of three and the Freedom input count out of five. Two jurisdictions with different coverage are not directly equivalent. Prefer comparisons with complete and comparable inputs; coverage alone does not establish accuracy. Unavailable values remain visible as gaps and sort after available values.
Cost of Living Index
The rankings display the stored absolute price index. Its population script rounds the World Bank price level ratio (PA.NUS.PPPC.RF) multiplied by 100, with an intended United States = 100 baseline. It does not normalize the global median to 50, and values can exceed 100. This is an economy-wide PPP price comparison, not a household spending basket or affordability ratio. The stored index row does not retain its input year or source release, so a specific value cannot be independently dated from this row alone. World Bank indicator definition.
Source Access and Lineage
These links identify datasets and providers used across the site. They do not establish the origin of every stored score. Health, Freedom and judicial independence rows do not preserve their observation years, source releases or derivation versions. Multiple import and proxy methods can write those fields; the exact method for an individual row is unverified. Oyster scores must therefore be distinguished from the original institutional indicators.
| Source | Coverage |
|---|---|
| World Bank | GDP, inflation, unemployment, education, infrastructure, demographics |
| WHO | Life expectancy, mortality, health expenditure and other health indicator series; separate from Oyster healthcare scores |
| Freedom House | Political rights and civil liberties datasets used by some score importers; row-level source releases are not preserved |
| 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 |
| Oyster List estimates | Some city prices, scores and climate summaries are modelled or have unverified origins; an API or model provider is not an observation source |
Observation Periods and Updates
Refreshes depend on source-specific imports; there is no verified quarterly refresh guarantee. Observation year, import timestamp and method review date describe different events. A newly imported historical value remains historical. WHO cards show the latest usable value for each stored sex, age, additional dimension and unit combination. Future-dated periods are kept separate and labelled because the stored rows do not identify observation versus projection status. Source revisions may recalculate historical values, so comparisons need the release actually imported; unknown release versions remain unknown.
Limitations
City prices and some city scores have modelled or unverified origins. Table membership and jurisdiction averages do not establish that a survey occurred. Treat these values as estimates unless the page supplies traceable evidence. Model-reported confidence is not measured accuracy. Legacy healthcare and governance scores also have incomplete lineage; presenting an aggregate cannot repair missing provenance. Cross-check the original datasets and current local information before relying on a comparison.
Corrections
Oyster List is responsible for these methods and labels. Report a data issue with the page URL, indicator, displayed period and a source reference. Corrections depend on verifying the source and affected records; no fixed update deadline is promised.