“…In 1986, Baumol and Abramovitz applied this theory to empirical research [20,21], regional convergence has gradually become an important topic. Currently, the studies of convergence and divergence mainly focus on economic growth, income, consumption expenditure, energy intensity, housing prices, and unemployment [22][23][24][25][26][27][28][29][30][31][32], and the types of convergence are various, including σ convergence (reflecting a decreasing trend of the urbanization level gap between regions or countries over time), β convergence (convergence only after controlling the factors affecting steady state), club convergence (convergence within subsamples), and stochastic convergence (examining whether the initial deviations from some hypothetical long-term equilibrium of an investigated indicator decrease over time). Correspondingly, the methods of measuring convergence are also different, such as CV sigma-convergence and beta-convergence, club convergence approach, Markov chain and spatial Markov chain methods, and econometric approach.…”