城市生活质量City Quality of Life

Quality of Living answers the question of "whether one lives well". Unlike sheer economic aggregate or "livability" (whether one lives comfortably), it comprehensively measures what a city actually gives ordinary citizens in terms of material living standards, public services, health and safety, and cultural provision: whether incomes are decent, whether housing is affordable, whether it is convenient to see a doctor or go to school, whether the air is clean, whether the streets are safe, and whether cultural life is rich.

Internationally, urban quality-of-living rankings have long been led by annual lists from a handful of institutions, whose results are easily quoted directly and whose ranks become entrenched. This CPPPS index does not reproduce the ranks of any existing list, but returns to underlying public data on medical care, education, safety, environment, housing prices, income, infrastructure, and culture, designs its own four-dimension indicator system (Scale + Quality + Innovation + Contribution), and recomputes the quality of living for about 30 major cities worldwide.

The "Contribution" dimension is a CPPPS signature: it does not judge a city by its fame or financial strength, but by the accessibility of public services that benefit ordinary citizens—housing affordability, income purchasing power, and the inclusiveness of cultural facilities—a dimension long absent from mainstream international quality-of-living rankings, and precisely where this index's value lies compared with existing lists.

Results: Tokyo, New York, Boston, Singapore, and London rank in the top five. Overall, cities with balanced quality, inclusive public services, and decent incomes rank ahead; megacities with severe air pollution, exorbitant housing prices, or weak income purchasing power are markedly dragged down in quality of living even if they are massive in scale and active in innovation. This ranking is based on approximations of public common knowledge (marked "subject to official figures"), with the algorithm, weights, and data sources all public, permanently free, for research and reference only.

In the field of urban quality of living there exist a few authoritative annual lists whose results are widely cited in policy and research. But their methodologies have three limitations: first, the dimensions over-weight "stability, medical care, education, infrastructure, and environment" while under-capturing income purchasing power and cultural provision; second, they rely mainly on expert scoring and surveys, with objective underlying data under-weighted; third, ranks remain entrenched over the years, making it hard to reflect real changes such as improvements in air quality and adjustments in housing policy.

CPPPS adheres to "not copying ranks, but computing from underlying data itself": it directly collects underlying data on medical care, education, safety, environment, housing prices, income, infrastructure, culture, and smart-city development, designs its own weights and model, and produces a reproducible, auditable independent ranking.

All indicators are first standardized to [0,1]: scale indicators (population, GDP) are log-transformed and then min-max normalized to avoid megacity scale crushing small and medium cities; environment, housing prices, and income use reference-anchored standardization—air quality anchored to the WHO PM2.5 guideline (5 μg/m³ as excellent, 40 μg/m³ as poor), house-price-to-income ratio anchored to affordability references (3 as very affordable, 30 as severely unaffordable), and income log-transformed and anchored (US$15,000–100,000) to reflect the diminishing marginal contribution of income to quality of living (the Easterlin paradox). Score-type indicators (safety, medical care, education, infrastructure, culture, smart city—all 0–100 ratings) are normalized directly against a perfect score of 100, avoiding noise amplification from min-max normalization within the narrow band of elite cities. Inverse indicators are inverted, and air quality is given a lower floor of 0.10 after standardization.

Scale characterizes a city's objective size, serving as the "base" of the evaluation. But scale itself is not the goal of quality of living—megacities tend to be congested, high-cost, and socially distant—so it carries the lowest weight in the composite score (8%).

Quality is the core of quality of living, accounting for 52% of the composite score. The five items use a weighted geometric mean rather than an arithmetic mean, reflecting the "bucket effect": any shortfall (such as poor air, weak public safety, or backward medical care) markedly lowers overall quality. Safety and environment carry the highest weights (25% each) because they are the hard bottom lines of quality of living—quality of living is not "one merit covering a hundred flaws", but "nothing can be missing".

Innovation is measured by a "smart city / digital services" index of a city's digital governance, digital infrastructure, and digital service capability, accounting for 10% of the composite score—digitalization is becoming a new dimension of contemporary quality of living (online government services, smart mobility, telemedicine).

Contribution is a CPPPS signature dimension, accounting for 30% of the composite score, measuring the accessibility of public services that benefit ordinary citizens: the house-price-to-income ratio (inverted, the lower the more affordable) carries the highest weight, with per-capita income (purchasing power, log-transformed to reflect diminishing returns) and the inclusiveness of cultural facilities equally emphasized—these bear directly on whether ordinary citizens can "afford housing, afford to buy, and live a fulfilling life", rather than on a city's fame or financial strength.

The Quality dimension uses a weighted geometric mean rather than an arithmetic mean: an arithmetic mean allows "one merit to cover a hundred flaws"—a city with excellent air but very poor public safety could still get a high average score; the geometric mean embodies "the shortest board determines the whole", where a serious deficiency in any quality element markedly lowers the quality score. Moreover, safety and environment carry the highest weights (25% each), further emphasizing that "safety and air are the hard bottom lines of quality of living": among environment, safety, medical care, education, and infrastructure, if any single item fails, citizens' daily experience is discounted.

Population, GDP, air quality (annual average PM2.5), per-capita income, and house-price-to-income ratio use approximations of public common knowledge, while public safety, medical care, education, infrastructure, culture, and smart city are approximate subjective scores, all marked "subject to official figures"; for specific values, please refer to the official statistics of each country/city. This model focuses on the objective supply side, material living standards, and the accessibility of public services, and does not include hard-to-quantify dimensions such as climate disaster risk and subjective satisfaction; approximations carry some error, and the ranking is for research and reference only.