全球宜居指数Global Livability Index

Livability is the most comprehensive and most down-to-earth indicator for measuring whether a city is "suitable for long-term living." Unlike economic aggregate or innovation intensity, it answers a simple question: Do the people living in this city breathe clean air, walk safe streets, afford medical care, afford schooling, afford housing, and travel conveniently?

Global livability rankings have long been dominated by five dimensions—stability, healthcare, education, infrastructure, and culture & environment—whose results are easily quoted directly from the annual lists of a few institutions. This CPPPS index does not reproduce the rankings of any existing list; instead, it returns to underlying public data (air quality, safety, healthcare, education, infrastructure, housing prices, culture, public transport, and smart-city level) and independently designs a four-dimensional indicator system (Scale + Quality + Innovation + Contribution) to recompute the livability of about 30 major global cities.

Among them, the "Contribution" dimension is a CPPPS distinctive feature: it does not judge a city by its fame or financial resources, but measures public services that benefit ordinary citizens—whether housing is affordable, whether public transport is accessible, and whether culture and green space are inclusive. This dimension has long been absent from mainstream international livability rankings, and is precisely where this index's value lies.

The evaluation results show that Tokyo, Osaka, New York, Singapore, and London rank in the top five. Overall, cities with high environmental quality, inclusive public services, and safety lead the list; megacities with prominent air pollution, distorted housing costs, or weak safety—even if large in scale and active in innovation—have their livability significantly dragged down. This ranking is based on approximate values from publicly available common knowledge (marked "subject to official figures"), with the algorithm, weights, and data sources fully public, permanently free, for research and reference only.

There are a few authoritative rankings in the field of global livability, and their results are often widely cited by media and policy. However, their methodology has three limitations: first, the dimensions are concentrated in "stability, healthcare, education, infrastructure, and environment," with insufficient coverage of the accessibility of public services for ordinary citizens (housing, transport, green space); second, they rely mainly on expert scoring and surveys, giving low weight to objective underlying data; and third, their rankings are long-frozen and cannot reflect real changes such as air quality improvement or housing policy adjustments.

CPPPS adheres to the principle of "not copying rankings, but computing from underlying data": it directly collects underlying data on air quality, public security, healthcare, education, infrastructure, housing prices, public transport, culture and green space, and smart-city level, and independently designs weights and models to produce a reproducible and auditable independent ranking.

All indicators are first standardized and mapped to [0,1]: quantitative indicators (population, GDP, PM2.5, house-price-to-income ratio) use range standardization (large-span scale indicators are first log-transformed to avoid megacities crushing small and medium-sized cities by size); rating-type indicators (safety, healthcare, education, infrastructure, smart city, public transport, culture and green space—all rated 0-100) are normalized directly against a full score of 100, to avoid amplifying noise by range-standardizing within the narrow band of elite cities. Negative indicators (PM2.5, house-price-to-income ratio) are inverted.

Scale captures the objective size of a city, serving as the "base" of evaluation. But scale itself is not the goal of livability—small cities are often more livable—so it carries the lowest weight (10%) in the composite score.

Quality is the core of livability, accounting for 50% of the composite score. The five items use geometric mean rather than arithmetic mean, reflecting the "barrel effect": any shortcoming (such as poor air or weak public security) will significantly drag down overall quality—livability is not "one strength covering all flaws," but "every element indispensable." After standardization, air quality is floored at 0.10 to prevent a single zero item from collapsing the whole to zero.

Innovation uses the "smart city" index to measure a city's digital governance, digital infrastructure, and innovation-driven capability, accounting for 15% of the composite score.

Contribution is a distinctive CPPPS dimension, accounting for 25% of the composite score, measuring public services that benefit ordinary citizens: the house-price-to-income ratio (inverted; the lower, the more affordable) carries the highest weight, with public transport and culture/green space equally weighted—these directly relate to the fairness and well-being of citizens' daily lives, rather than the city's fame or financial resources.

The Quality dimension uses geometric mean rather than arithmetic mean: arithmetic mean allows "one strength to cover all flaws"—a city with excellent air but very poor public security could still obtain a high average score—whereas geometric mean reflects "the weakest link determines the whole," so a serious deficiency in any quality element significantly lowers the quality score. This is consistent with the view that "livability is a hard constraint where every element is indispensable": if any one of air quality, safety, healthcare, education, or infrastructure is substandard, citizens' living experience is discounted.

Population, GDP, air quality (annual average PM2.5), and house-price-to-income ratio use approximate values from publicly available common knowledge, while public security, healthcare, education, infrastructure, smart city, public transport, and culture/green space use approximate subjective scores, all marked "subject to official figures"—please refer to the official statistics of each country/city for specific values. This model focuses on the objective supply side and the accessibility of public services, and does not include climate disaster risk, subjective satisfaction, and other dimensions that are hard to quantify; approximate values also contain errors, so the ranking is for research and reference only.