The article looks at how different regions in China have grown economically from 1978 to 2013. They used various methods to analyze this, like looking at income differences and using statistical models. The results show that overall, income gaps between regions decreased during this time. They also found that there was a clear trend of regions with lower incomes catching up to those with higher incomes, especially from 1995 to 2013. This means that regions in China are getting closer in terms of economic growth.