A Composite Index of High-Quality Economic Development in China: Long-Term Evidence from the Yangtze River Economic Belt

Research on the Yangtze River Economic Belt (YREB) lacks a long-horizon, internally consistent measure of high-quality economic development (HQED), which limits comparable tracking across years and provinces. To address this gap, a composite HQED index for 11 provinces/municipalities over 1998–2023 is constructed from 16 indicators spanning economic vitality, achievement sharing, and green development. Indicators are direction-adjusted and min–max standardized, and the entropy weights and Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS) are implemented with ideal and anti-ideal points fixed on the full panel to preserve intertemporal comparability, while a sign-adjusted principal component analysis (PCA) index is employed for validation. Results indicate a steady rise in average HQED, accompanied by declining cross-provincial dispersion, consistent with gradual convergence and faster catch-up in several inland provinces. Relatively high weights on trade dependence, labor productivity, and per-capita income highlight openness and factor efficiency as key differentiators of development quality. Policy implications include province-specific target setting, prioritizing human-capital and productivity programs in catching-up regions, balancing external integration with green governance in coastal leaders, and expanding public-service access to strengthen achievement sharing.