Studies of the Relationship between City Size and Urban Benefits in China Based on a Panel Data Model

Policy regarding the size of cities is an important component of China's urban policy prescription. We used a curvilinear regression model in this study to identify the optimal function and conducted curve panel data regression analysis on the panel data of the benefits of the economy, ecosystem services, and city size in China. In doing so, we obtained the regression relationship between city size and the benefits of the economy, environment, and resources of a city. Our main findings are as follows: (1) city size is not the most important factor determining a city's benefits. However, there is a significant difference in the average city benefit between cities of various sizes; (2) city per capita GDP increase exhibited an inverted-N-shaped relationship with increasing city size, initially decreasing but subsequently increasing. The city size corresponding to the maximum value was usually higher than or close to the actual city size. Thus, it can be concluded that when a city's population is more than 1 million, its per capita output increases; (3) a city's resource services benefits all exhibited the trend of improving with increasing city size. This trend was particularly pronounced among cities with a population of less than 1 million; and (4) a city's environmental services benefits exhibited an inverted-U-shaped relationship with city size, initially increasing but subsequently decreasing.