The evolution of Zipf's law indicative of city development

TL;DR

This paper explores different mathematical models of Zipf's law for city sizes, revealing a progression from three-parameter to one-parameter models and applying empirical data from China to validate these models.

Contribution

It introduces a comprehensive framework unifying Zipf models through hierarchical scaling laws and highlights the evolution of city-size distribution patterns.

Findings

Three-parameter Zipf model effectively describes complex city-size distributions.

Hierarchical scaling laws unify various Zipf models.

City-size distribution patterns evolve from three-parameter to one-parameter models.

Abstract

Zipf's law of city-size distributions can be expressed by three types of mathematical models: one-parameter form, two-parameter form, and three-parameter form. The one-parameter and one of the two-parameter models are familiar to urban scientists. However, the three-parameter model and another type of two-parameter model have not attracted attention. This paper is devoted to exploring the conditions and scopes of application of this Zipf models. By mathematical reasoning and empirical analysis, new discoveries are made as follows. First, if the size distribution of cities in a geographical region cannot be described with the one- or two-parameter model, maybe it can be characterized by the three-parameter model with a scaling factor and a scale-translational factor. Second, all these Zipf models can be unified by hierarchical scaling laws based on cascade structure. Third, the patterns of city-size distributions seems to evolve from three-parameter mode to two-parameter mode, and then to one-parameter mode. Four-year census data of China's cities are employed to verify the three-parameter Zipf's law and the corresponding hierarchical structure of rank-size distributions. This study is revealing for people to understand the scientific laws of social systems and the property of urban development.