## 5 Interaction between Planning Research Investment Intensity and Urbanization
### Path Choice of Interaction between Planning Research Investment and Urbanization  
According to the interaction feature between planning research intensity and urbanization rate of major countries, this study concluded the interactions into six categories, which can be further summarized as two ways for countries in terms of different interactions. The study of the interaction between planning research investment and urbanization proposes the influence of planning research investment might result in different urbanization responds.  
In other studies on interaction between macro-economy and urbanization, for example, researchers proposed a scatter plot of urbanization rate and GDP per capita of major countries. Through relevant studies, it is found that the **urbanization paths** of 47 major countries are mainly divided into two **groups**. In the urbanization, major countries can be divided into two groups when the urbanization rate reaches 70%. For one category, after the urbanization rate reaches 70%, the GDP per capita of these countries increases, normally exceeding 15,000 US dollars. In the other category, after the urbanization rate is over 70%, the GDP per capita will not increase and normally cannot grow over 15,000 US dollars. Therefore, such countries are stagnated in urbanization and economy [37].  
Since urban planning research represents solving urban problems, enhancing the quality of urbanization, and improving living standards, more urban planning research is the basis for ensuring high-quality urbanization development.  
The per capita planning research investment and urbanization rate of 47 major countries in 2019 were selected and made on the scatter plot, with the horizontal axis being the urbanization rate and the vertical axis being the 'per capita planning research investment', represented by 'per capita amount of planning research literature'. It can be found that these countries are divided into two groups as well. In detail, the group whose urbanization rate and the per capita amount of urban planning literature increase simultaneously is called '**Stand group**', and the group whose urbanization rate increases while the per capita amount of planning literature stagnates is called '**Lay group**'. By observing the two groups, it can be found that the types of corresponding countries have clear features. For instance, the Stand group is made up of developed countries mostly, while the Lay group consists of developing countries mostly. The **turning point** between the two groups is roughly at a 70% urbanization rate. Countries experience a process from low urbanization rate to high, thus, the Stand group and Lay group can be understood as two **approaches** in the development of urbanization, which stands for (1): **Stand approach**, high urbanization and planning research investment, mostly happened in developed countries, and (2): **Lay approach**, high planning research investment but low urbanization rate, mostly in developing countries. According to the findings, obviously, countries should choose a Stand approach with both high urbanization and planning research intensity and reasonably increase the investment in planning research before the turning point as means of strengthening the research basis, so as to fulfill a better urbanization development (Figure 4).