Invention complexity, latent innovation capabilities, and economic development in upper middle-income countries

This paper examines how upper middle-income countries (UMICs) transition from imitation- to innovation-led growth, and whether sustained innovation capabilities drive long-run economic development. Building on the World Bank's World Development Report 2024 (WDR 2024), we develop a unified theoretical and methodological framework integrating endogenous growth, Schumpeterian growth, economic complexity, and entrepreneurial self-discovery approaches. We introduce two novel indicators: the Invention Complexity Index (ICI) , which measures the diversity and sophistication of national invention capabilities, and the Invention–Production Complexity Gap (IPCG) , which captures latent innovation capabilities as the gap between invention and production capabilities. Using European Patent Office PATSTAT data (1987–2019) and a panel of national indicators for 67 countries, we estimate pooled OLS models with fixed effects across three income-range samples. The results show that invention complexity is strongly associated with income levels and that latent innovation capabilities become a robust predictor of growth within the UMIC range: a one-standard-deviation increase in the IPCG corresponds to a 0.50% increase in annual growth. They also reveal divergence across countries—clear evidence of an upper middle-income trap. These findings provide empirical support for the middle-income trap hypothesis, the Schumpeterian distance-to-frontier hypothesis, and the WDR 2024 dual-transition framework, revealing that the shift from imitation- to innovation-led growth is a stage-specific challenge concentrated in the UMIC range. The study contributes new theoretical and methodological tools for measuring invention complexity and latent innovation capabilities and offers policy insights on aligning innovation and industrial strategies to foster structural transformation, escape the middle-income trap, and advance toward high-income status. • Introduces the Invention Complexity Index (ICI) using global patent data. • Also introduces the Invention–Production Complexity Gap (IPCG) to capture latent innovation capabilities. • Links invention complexity to economic growth across income stages (1987–2019). • Finds latent innovation capabilities drive growth within the upper middle-income range. • Offers policies for aligning innovation and production systems to escape the middle-income trap.