城市化水平与人均国民生产总值的统计关系在８０年代被建立,从理论上分析这个统计关系能加深对城市与经济发展之关系的理解。从经济学的要素替代和需求收入弹性原理概括了城市化的发展机制,认为任何一个国家或地区的城市化都遵从它。并构造了全国人均国民生产总值与城市人均国民生产总值、乡村人均国民生产总值、城市化水平的关系,它是普适的。如果假设城市、乡村人均国民生产总值的增长分别引起的全国人均国民生产总值的增长总是占据了一个不变的份额,同时,城市人均国民生产总值与乡村人均国民生产总值之差与全国人均国民生产总值成正比,那么,就可以据此演绎出这个统计关系。第二个前提暗示了一个城乡发展差距的倒“Ｕ”字型过程

Usually,forecasting urban population is a prior work to predicting urban land use change.A nice statistical relationship between urbanization level and per capita GNP was set up in the 1980s,so that it is possible to forecast urbanization level and urban population from economic development.It is necessary to analyze the relationship theoretically in order to deepen our understanding.Firstly,the author outlines an urbanization mechanism based upon production factor substitute and demand elasticity of income.Then a function is created,which connects urbanization level with whole GNP,per capita urban gross product and rural gross product.Finally the statistical relationship is derived from two assumptions.One is that the growth share of whole GNP per capita resulted from the increase in per capita gross product in city and countryside is always constant at any point in time respectively.Another is that the difference between per capita product of them is in direct ratio to the whole GNP per capita.The second implies an uneven urban rural development history of inverse “U”.